APPLICATION BROCHURE Chillers and Heat Pumps Hydraulics Manual Suggestions for the hydraulic integration of chillers and heat pumps
Table of Contents From practical experience, for your practical needs... 3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Chiller/heat pump with single-circuit buffer tank and one consumer... 4 Chiller/heat pump with plate heat exchanger for system separation, single-circuit buffer tank and one consumer... 9 Chiller/heat pump with dual circuit-buffer tank and extensive system hydraulics... 14 Chilled/warm water generator with plate heat exchanger for the system separation, dual circuit buffer tank and extensive system hydraulics... 19 Chiller/heat pump with single-circuit buffer tank and several different consumers... 24 Chiller/heat pump with single-circuit buffer tank and several consumers of the same power rating... 29 Production of chilled/warm water with plate heat exchanger for system separation and secondary-sided inverter pump... 34 Sequence control gear of chiller/heat pump with dual circuit buffer tank and extensive system hydraulics... 39 Chiller, water-cooled plant, integration of a heat-rejection system... 44 Chiller, water-cooled plant, integration in the heat-rejection system with cold weather start control for all-year operation... 47 Chiller, water-cooled plant, with heat-rejection system and free cooling function... 51 Chiller, air-cooled, integration of desuperheater for heat recovery... 57 Chiller, water-cooled plant, with heat recovery and heat-rejection system... 61 Cold/warm water generator with variable-speed pump, single-circuit buffer tank and 2-way valves (VPS A-Control)... 66 Cold-/warm water generators with variable speed pumps in primarily and secondary circuits (VPS D-Control)... 72 Cold/warm water generator with variable-speed pump and single-circuit buffer tank with 3-way valves (VPS A-Control)... 78 Legend... 83 2 PR-2014-0112-GB Subject to modifications R2-02/2017
_0 From practical experience, for your practical needs This is the basic idea behind the creation of this manual. Engineers and technicians should be optimally supported in their work when it concerns system integration of chillers or heat pumps. The following pages outline and explain the most common hydraulic circuits for integrating these units in various application areas. This document presents recommendations and useful notices, which however do not replace individual system planning and configuration of hydraulic components. COPYRIGHT NOTE The reproduction, distribution and utilization of this document as well as the communication of its contents to others without express authorization is prohibited. Offenders will be held liable for the payment of damages. All rights reserved in the event of the grant of a patent, utility model or design. PR-2014-0112-GB Subject to modifications R2-02/2017 3
01 Chiller/heat pump with single-circuit buffer tank and one consumer Area of application Generation of cold or warm water for comfort air conditioning or for process applications. The deployment of a single-circuit buffer tank system is a simple consumer network condition, which however requires the satisfaction of important prerequisites. Unit Buffer tank Consumers Functional principle of the hydraulics For released units, the medium flows from the buffer tank to the water pump in the unit. The medium is chilled or warmed up for the required load reduction. The chilled/warm water now flows to the consumer and is then warmed up or chilled down again there. The 3-way valve in the position A AB is fully opened at maximum capacity reduction. The bypass line B is closed. If the load reduction of the consumer drops, then the bypass line B is opened. This ensures a constant water/volume flow across the unit, regardless of the load reduction. The unit requires a constant water/volume flow for trouble-free operation. Therefore variable speed pumps must not be used. If the bypass line B is completely opened because of the lack of load reduction, water no longer circulates to the consumer. The water temperature approaches the unit setpoint and the compressors gradually switch off. The water pump continuously remains in operation in order to record the current water temperatures in the system. If the load reduction increases again, the unit switches on the individual compressors again depending on how far the temperature deviates from the setpoint. It is important for the regulation of the unit that a constant water quantity is transported over the evaporator / condenser at all times. Variable water quantities lead to discontinuous heat transfers and thus to undefined fluctuating ratings of the heat exchanger. This can lead to operational malfunctions, which are recorded with the unit controller. 4 PR-2014-0112-GB Subject to modifications R2-02/2017
The possible fault signals are: Insufficient evaporating pressure Low pressure Frost protection Flow switch Low water flow in the plant 01 For this reason, no 2-way valves can be employed for the depicted hydraulic system! Important hydraulic components Single circuit buffer tank: Water filter: Paddle-type flow switch: Expansion tank: Water system pressure switch: The buffer tank primarily serves to increase the water volume in the hydraulic system in order to ensure a minimum runtime of the compressors and to prevent unnecessarily frequent on and off switching of the compressors. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. PR-2014-0112-GB Subject to modifications R2-02/2017 5
01 Regulating valves: Ventilation: Charging and draining: In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. External enabling device: Pump enabling: Alarm signal: Control and regulation The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity of the unit and the associated water temperature may only be controlled with the internal unit controls. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After successful release, the unit switches the pump on and checks the current with an internal differential pressure switch and additionally with a paddle-type flow switch mounted on-site. As soon as a stable water flow is ensured, the water temperature is measured and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill the water to the setpoint. After reaching the setpoint, the first compressor switches off. Additional compressors are switched off or on depending on the temperature change. The water pumps remain in continuous operation so that the plant can perform readings of the current water temperature in the system. After switching the unit off with the remote ON/OFF contact, the compressors are driven down and then switched off. The pump is switched off after the expiration of a programmed delay period. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. 6 PR-2014-0112-GB Subject to modifications R2-02/2017
Frost protection 01 Remember: If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 7
01 Unit Buffer tank Consumers 8 PR-2014-0112-GB Subject to modifications R2-02/2017
Chiller/heat pump with plate heat exchanger for system separation, single-circuit buffer tank and one consumer 02 Area of application Generation of cold or warm water for comfort air conditioning or for process applications. By using a single-circuit buffer tank system and a plate heat exchanger for system separation, a simple consumer network is conditioned, where however important prerequisites must be satisfied. Unit Plate heat exchanger Buffer tank Consumers Primary page Secondary side Functional principle of the hydraulics A plate heat exchanger creates a system separation in this hydraulic scheme in order to ensure freeze resistance for low outside temperatures without requiring the entire plant to be filled with a water-glycol mixture. The buffer tank is fitted in the secondary circuit of the plate heat exchanger in order to reduce the quantity of glycol required and thereby to reduce costs. In order to be able to make use of the entire system content, primary and secondary side, it is mandatory to always operate both pumps together. The entire plant can thereby be employed to guarantee the minimum system contents, especially because the buffet tank is in the secondary circuit. The minimum system content is required to guarantee the minimum runtime of the compressors. For the released unit, the medium flows to the secondary side of the buffer tank through the water pump in the secondary side of the plate heat exchanger of the system separation, which provides the primary side of the unit with the chilled/ heated water-glycol mixture. The medium is chilled or warmed up for the required load reduction. The chilled/warm water now flows to the consumer and is once again warmed up or cooled down. The 3-way valve in the position A AB is fully opened at maximum capacity reduction. The bypass line B is closed. If the load reduction of the consumer drops, then the bypass line B is opened. This ensures that, independent of the load reduction, a PR-2014-0112-GB Subject to modifications R2-02/2017 9
02 constant water volume flow over the plate heat exchanger is present. Abrupt temperature variations on the primary part of the plate heat exchanger are thereby avoided. The unit requires a constant water/volume flow for trouble-free operation. Therefore, pumps that are speed-regulated during operation must not be used. If the bypass line B is completely opened because of the lack of load reduction, water no longer circulates to the consumer. The water temperature approaches the unit setpoint and the compressors gradually switch off. Both water pumps remain continuously in operation in order to record the current water temperatures in the system. If the load reduction increases again, the unit switches on the individual compressors again depending on how far the temperature deviates from the setpoint. It is important for the regulation of the unit that a constant water quantity is transported in the unit over the evaporator / condenser at all times. Variable water quantities lead to discontinuous heat transfers and thus to undefined fluctuating ratings of the heat exchanger. This can lead to operational malfunctions, which are recorded with the unit controller. The possible fault signals are: Insufficient evaporating pressure Low pressure Frost protection Flow switch Low water flow in the plant For this reason, no 2-way valves can be employed for the depicted hydraulic system! Important hydraulic components Single circuit buffer tank: Water filter: Paddle-type flow switch: Expansion tank: The buffer tank primarily serves to increase the water volume in the hydraulic system in order to ensure a minimum runtime of the compressors and to prevent unnecessarily frequent on and off switching of the compressors. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, 10 PR-2014-0112-GB Subject to modifications R2-02/2017
Water system pressure switch: Regulating valves: Ventilation: Charging and draining: Plate Heat Exchangers: 02 this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. The plate heat exchanger is used in a hydraulic plant as system separation. Reasons for the use of a plate heat exchanger could be: Separation between water-glycol circuit and water circuit Different temperature ranges and protection of a circuit against too high or too low temperatures Different pressure ranges and protection of a circuit against too high pressure Functioning as hydraulic switch Control and regulation External enabling device: The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity of the unit and the associated water temperature may only be controlled with the internal unit controls. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After successful release, the unit switches the pump on and checks the current with an internal differential pressure switch and additionally with a paddle-type flow switch mounted on-site. As soon as a stable water flow is ensured, the water temperature is measured and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. After reaching the setpoint, the first compressor switches off. Additional compressors are switched off or on depending on the temperature change. The water pumps remain in continuous operation so that the plant can perform readings of the current water temperature in the system. PR-2014-0112-GB Subject to modifications R2-02/2017 11
02 Pump enabling: Alarm signal: After switching the unit off with the remote ON/OFF contact, the compressors are driven down and then switched off. The pump is switched off after the expiration of a programmed delay period. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. Both the water pump in the primary as well as in the secondary circuit must be operated with the enabling contact. Both pumps must always be simultaneously in operation. If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. Frost protection If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30 % ethylene glycol. All components installed outdoors are, in this case, protected from freezing with a water-glycol mixture. Since a plate heat exchanger was employed as a system separation, filling the entire plant with anti-freeze is not required. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. 12 PR-2014-0112-GB Subject to modifications R2-02/2017
02 Plate heat Unit exchanger Buffer tank Primary page Secondary side Consumers PR-2014-0112-GB Subject to modifications R2-02/2017 13
03 Chiller/heat pump with dual circuit-buffer tank and extensive system hydraulics Area of application Generation of cold or warm water for comfort air conditioning or for process applications. The consumer network can take on complex forms with the deployment of a dual circuit buffer tank system, where however important prerequisites must be satisfied. Consumers Unit Buffer tank Plant circuit Consumer circuit Functional principle of the hydraulics For released units, the medium flows from the buffer tank to the water pump in the unit. The medium is chilled or warmed up for the required load reduction. The chilled/warm water now once again flows into the buffer tank. In case there are no requirements on chilled/warm water, the buffer tank guarantees the minimum runtime of the compressors. A constant water volume flow through the unit is guaranteed with the dual circuit buffer tank. The consumer circuit can be designed in any number of complex forms. This includes e.g.: Employment of speed-regulated pumps Employment of 2-way or 3-way valves Consumer circuits in different temperature ranges. Consumer circuits with various power capacities and water/volume flows No influence on the plant circuit can arise and a constant water quantity to the unit is guaranteed at all times. 14 PR-2014-0112-GB Subject to modifications R2-02/2017
Important hydraulic components 03 Dual circuit buffer tank Water filter: Paddle-type flow switch: Expansion tank: Water system pressure switch: The dual circuit buffer tank fulfills the following functions: Assurance of the entire minimum system contents. The minimum runtimes of the compressors are observed and unnecessarily frequent compressor switch on and off is prevented. Hydraulic switch for the separation of plant and consumer circuits Guarantee of a thermal stratification within the container Standing buffer tanks must be used for this purpose. The chilled water supply in the plant circuit and the chilled water inlet in the consumer circuit must be attached at the lower connections of the buffer tank. In order to determine the minimum system content of the unit, only the volume of the buffer tank and the volume of the piping between device and buffer tank may be used. However, the volume of the consumer circuit is not taken into account. Dual circuit buffer tanks for chillers are characterized by their special design whose structure favors chilled-water stratification. Perforated perfusion pipes or perforated separation plates are used in the upper and lower area of the tank. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. PR-2014-0112-GB Subject to modifications R2-02/2017 15
03 Regulating valves: Ventilation: Charging and draining: In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. External enabling device: Pump enabling: Alarm signal: Control and regulation The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity of the unit and the associated water temperature may only be controlled with the internal unit controls. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After successful release, the unit switches the pump on and checks the current with an internal differential pressure switch and additionally with a paddle-type flow switch mounted on-site. As soon as a stable water flow is ensured, the water temperature is measured and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. After reaching the setpoint, the first compressor switches off. Additional compressors are switched off or on depending on the temperature change. The water pumps remain in continuous operation so that the plant can perform readings of the current water temperature in the system. After switching the unit off with the remote ON/OFF contact, the compressors are driven down and then switched off. The pump is switched off after the expiration of a programmed delay period. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. 16 PR-2014-0112-GB Subject to modifications R2-02/2017
Frost protection 03 Remember: If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 17
03 Unit Buffer tank Plant circuit Consumer circuit Consumers 18 PR-2014-0112-GB Subject to modifications R2-02/2017
04 Chilled/warm water generator with plate heat exchanger for the system separation, dual circuit buffer tank and extensive system hydraulics Area of application Generation of cold or warm water for comfort air conditioning or for process applications. Chilled/warm water generator with plate heat exchanger for the system separation, dual circuit buffer tank and extensive system hydraulics Consumers Unit Plate heat exchanger Buffer tank Primary page Secondary side Plant circuit Consumer circuit Functional principle of the hydraulics A plate heat exchanger creates a system separation in this hydraulic scheme in order to ensure freeze resistance for low outside temperatures without requiring the entire plant to be filled with a water-glycol mixture. The buffer tank is fitted in the secondary circuit of the plate heat exchanger in order to reduce the quantity of glycol required and thereby to reduce costs. In order to be able to employ the buffer tank correctly, it is absolutely required that the pumps on the primary and secondary side of the plate heat exchanger are always operated together. The dual circuit buffer tank can thereby be employed to guarantee the minimum system contents, especially because these are in the secondary circuit. The minimum system content is required to guarantee the minimum runtime of the compressors. For a released unit, the medium of the buffer tank flows through the water pump to the secondary side of the plate heat exchanger of the system separation, which provides the primary side of the unit with chilled/heated water glycol mixture. The medium is chilled or warmed up for the required load reduction. The chilled/warm water now once again flows into the buffer tank. In case there are no requirements on chilled/warm water, the buffer tank guarantees the minimum runtime of the compressors. PR-2014-0112-GB Subject to modifications R2-02/2017 19
04 A constant water volume flow in the unit is guaranteed because of the plate heat exchanger for the system separation. The minimum system content is guaranteed by the parallel operation of the primary and secondary pump as well as the dual circuit buffer tank. The consumer circuit can be designed in any number of complex forms. This includes e.g.: Employment of speed-regulated pumps Employment of 2-way or 3-way valves Consumer circuits in different temperature ranges. Consumer circuits with various power capacities and water/volume flows No influence on the generator circuit can arise and a constant water quantity to the unit is guaranteed at all times. Important hydraulic components Dual circuit buffer tank Water filter: Paddle-type flow switch: Expansion tank: The dual circuit buffer tank fulfills the following functions: Assurance of the entire minimum system contents. The minimum runtimes of the compressors are observed and unnecessarily frequent compressor switch on and off is prevented. Hydraulic switch for the separation of plant and consumer circuits Guarantee of a thermal stratification within the container Standing buffer tanks must be used for this purpose. The chilled water supply in the plant circuit and the chilled water inlet in the consumer circuit must be attached at the lower connections of the buffer tank. In order to determine the minimum system content of the unit, in this case only the volume of the buffer tank, the plate heat exchanger, and the piping on the primary and secondary side may be employed. However, the volume of the consumer circuit is not taken into account. Dual circuit buffer tanks for chillers are characterized by their special design whose structure favors chilled-water stratification. Perforated perfusion pipes or perforated separation plates are used in the upper and lower area of the tank. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pres- 20 PR-2014-0112-GB Subject to modifications R2-02/2017
Water system pressure switch: Regulating valves: Ventilation: Charging and draining: Plate Heat Exchangers: 04 sure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. The plate heat exchanger is used in a hydraulic plant as system separation. Reasons for the use of a plate heat exchanger could be: Separation between water-glycol circuit and water circuit Different temperature ranges and protection of a circuit against too high or too low temperatures Different pressure ranges and protection of a circuit against too high pressure Functioning as hydraulic switch Control and regulation External enabling device: Pump enabling: The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity of the unit and the associated water temperature may only be controlled with the internal unit controls. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After successful release, the unit switches the pump on and checks the current with an internal differential pressure switch and additionally with a paddle-type flow switch mounted on-site. As soon as a stable water flow is ensured, the water temperature is measured and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. After reaching the setpoint, the first compressor switches off. Additional compressors are switched off or on depending on the temperature change. The water pumps remain in continuous operation so that the plant can perform readings of the current water temperature in the system. After switching the unit off with the remote ON/OFF contact, the compressors are driven down and then switched off. The pump is switched off after the expiration of a programmed delay period. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. Both the water pump in the primary as well as in the secondary circuit must be operated with the enabling contact. Both pumps must always be simultaneously in operation. PR-2014-0112-GB Subject to modifications R2-02/2017 21
04 Alarm signal: If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. Frost protection If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. All components installed outdoors are, in this case, protected from freezing with a water-glycol mixture. Since a plate heat exchanger was employed as a system separation, filling the entire plant with anti-freeze is not required. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (Data & Facts) of each unit include diagrams of the operating limits which must be taken into account. 22 PR-2014-0112-GB Subject to modifications R2-02/2017
04 Unit Plate heat exchanger Primary page Secondary side Consumers Buffer tank Plant circuit Consumer circuit PR-2014-0112-GB Subject to modifications R2-02/2017 23
05 Chiller/heat pump with single-circuit buffer tank and several different consumers Area of application Generation of cold or warm water for comfort air conditioning or for process applications. The deployment of a single-circuit buffer tank system is a simple consumer network condition, which however requires the satisfaction of important prerequisites. Geko Geko Geko Geko Geko Geko Geko Unit Buffer tank Functional principle of the hydraulics For released units, the medium flows from the buffer tank to the water pump in the unit. The medium is chilled or warmed up for the required load reduction. The chilled/warm water now flows through the consumer and is once again warmed up or cooled down. In this case, it can be about consumers of the same or unequal power consumption at identical water temperatures. The required water quantity must be adjusted individually for every consumer with balancing valves. The use of 3-way valves regulates the consumer's capacity and ensures a constant volume flow through the unit. For maximum capacity reduction, the 3-way valve is fully opened to the position A AB. The bypass line B is closed. If the load reduction of the consumer drops, then the bypass line B is opened. This ensures a constant water/volume flow across the unit, regardless of the load reduction. The unit requires a constant water/volume flow for trouble-free operation. Therefore variable speed pumps must not be used. If the bypass line B is completely opened because of the lack of load reduction, water no longer circulates to the consumer. The water temperature approaches the unit setpoint and the compressors gradually switch off. The water pump continuously remains in operation in order to record the current water temperatures in the system. If the load reduction increases again, the unit switches 24 PR-2014-0112-GB Subject to modifications R2-02/2017
05 on the individual compressors again depending on how far the temperature deviates from the setpoint. Since a constant water volume flow is required for the fault-free operation of the unit, no variable-speed pumps may be used. It is important for the regulation of the unit that a constant water quantity is transported over the evaporator / condenser at all times. Variable water quantities lead to discontinuous heat transfers and thus to undefined fluctuating ratings of the heat exchanger. This can lead to operational malfunctions, which are recorded with the unit controller. The possible fault signals are: Insufficient evaporating pressure Low pressure Frost protection Flow switch Low water flow in the plant For this reason, no 2-way valves can be employed for the depicted hydraulic system! Important hydraulic components Single circuit buffer tank: Water filter: Paddle-type flow switch: Expansion tank: The buffer tank primarily serves to increase the water volume in the hydraulic system in order to ensure a minimum runtime of the compressors and to prevent unnecessarily frequent on and off switching of the compressors. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. PR-2014-0112-GB Subject to modifications R2-02/2017 25
05 Water system pressure switch: Regulating valves: Ventilation: Charging and draining: If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. Control and regulation External enabling device: Pump enabling: Alarm signal: The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity of the unit and the associated water temperature may only be controlled with the internal unit controls. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After successful release, the unit switches the pump on and checks the current with an internal differential pressure switch and additionally with a paddle-type flow switch mounted on-site. As soon as a stable water flow is ensured, the water temperature is measured and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. After reaching the setpoint, the first compressor switches off. Additional compressors are switched off or on depending on the temperature change. The water pumps remain in continuous operation so that the plant can perform readings of the current water temperature in the system. After switching the unit off with the remote ON/OFF contact, the compressors are driven down and then switched off. The pump is switched off after the expiration of a programmed delay period. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. 26 PR-2014-0112-GB Subject to modifications R2-02/2017
Frost protection 05 Remember: If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (Data & Facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 27
05 Geko Geko Geko Geko Geko Geko Unit Buffer tank Geko 28 PR-2014-0112-GB Subject to modifications R2-02/2017
Chiller/heat pump with single-circuit buffer tank and several consumers of the same power rating 06 Area of application Generation of cold or warm water for comfort air conditioning or for process applications. The deployment of a single-circuit buffer tank system is a simple consumer network condition, which however requires the satisfaction of important prerequisites. Geko Geko Geko Geko Geko Geko Geko Unit Buffer tank Functional principle of the hydraulics For released units, the medium flows from the buffer tank to the water pump in the unit. The medium is chilled or warmed up for the required load reduction. The chilled/warm water now flows through the consumer and is once again warmed up or cooled down. This applies for consumers with the same power rating, who in this case are connected according to the Tichelmann principle to ensure an almost equal water quantity at full load via every individual consumer. Balancing valves are not needed for this reason. The use of 3-way valves regulates the consumer's capacity and ensures a constant volume flow through the unit. Since a constant water volume flow is required for the fault-free operation of the unit, no variable-speed pumps may be used. For maximum capacity reduction, the 3- way valve is fully opened to the position A AB. The bypass line B is closed. If the load reduction of the consumer drops, then the bypass line B is opened. This ensures a constant water/volume flow across the unit, regardless of the load reduction. The unit requires a constant water/volume flow for trouble-free operation. Therefore variable speed pumps must not be used. If the bypass line B is completely opened because of the lack of load reduction, water no longer circulates to the consumer. The water temperature approaches the unit setpoint and the compressors gradually PR-2014-0112-GB Subject to modifications R2-02/2017 29
06 switch off. The water pump continuously remains in operation in order to record the current water temperatures in the system. If the load reduction increases again, the unit switches on the individual compressors again depending on how far the temperature deviates from the setpoint. It is important for the regulation of the unit that a constant water quantity is transported over the evaporator / condenser at all times. Variable water quantities lead to discontinuous heat transfers and thus to undefined fluctuating ratings of the heat exchanger. This can lead to operational malfunctions, which are recorded with the unit controller. The possible fault signals are: Insufficient evaporating pressure Low pressure Frost protection Flow switch Low water flow in the plant For this reason, no 2-way valves can be employed for the depicted hydraulic system! Important hydraulic components Single circuit buffer tank: Water filter: Paddle-type flow switch: Expansion tank: Water system pressure switch: The buffer tank primarily serves to increase the water volume in the hydraulic system in order to ensure a minimum runtime of the compressors and to prevent unnecessarily frequent on and off switching of the compressors. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. 30 PR-2014-0112-GB Subject to modifications R2-02/2017
Regulating valves: Ventilation: Charging and draining: 06 In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. Control and regulation External enabling device: Pump enabling: Alarm signal: The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity of the unit and the associated water temperature may only be controlled with the internal unit controls. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After successful release, the unit switches the pump on and checks the current with an internal differential pressure switch and additionally with a paddle-type flow switch mounted on-site. As soon as a stable water flow is ensured, the water temperature is measured and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. After reaching the setpoint, the first compressor switches off. Additional compressors are switched off or on depending on the temperature change. The water pumps remain in continuous operation so that the plant can perform readings of the current water temperature in the system. After switching the unit off with the remote ON/OFF contact, the compressors are driven down and then switched off. The pump is switched off after the expiration of a programmed delay period. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. PR-2014-0112-GB Subject to modifications R2-02/2017 31
06 Frost protection Remember: If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. 32 PR-2014-0112-GB Subject to modifications R2-02/2017
06 Geko Geko Geko Geko Geko Geko Unit Buffer tank Geko PR-2014-0112-GB Subject to modifications R2-02/2017 33
07 Production of chilled/warm water with plate heat exchanger for system separation and secondary-sided inverter pump Area of application Generation of cold or warm water for comfort air conditioning or for process applications. The consumers are primarily equipped with straight-way valves for regulation. The secondary-sided consumer network therefore has a variable plant characteristics curve. To optimize energy consumption and flow pattern, a speed-regulated pump is used as a secondary pump. Geko Geko Geko Geko Geko Geko Geko Unit Buffer tank Plate Heat Exchanger Primary page Secondary side Functional principle of the hydraulics The secondary side is equipped with a speed-regulated pump. The unit requires a constant water flow-rate for trouble-free operation, therefore a system separation is created using a plate heat exchanger. Thus, the primary circuit has a constant water flow and the secondary circuit has a variable water flow. Due to the variable water flow in the secondary circuit, the necessary buffer tank must be arranged in the primary circuit to guarantee the minimum system contents. To ensure freeze resistance, the primary circuit is operated with a water-glycol mixture. For the released unit, pump P1 is in operation and provides the unit with a constant water-glycol mass flow. Via the plate heat exchanger, a heat exchange with the secondary-sided consumer network takes place, depending on the operation of the secondary-sided speed-regulated pump. The secondary-sided consumer network can be freely designed. By using a speedregulated pump, straight-way regulating valves can be used. The secondary pump can adjust the pump characteristics of a variable plant characteristics curve within the variable pump characteristics range and can set an optimal operating point. 34 PR-2014-0112-GB Subject to modifications R2-02/2017
Important hydraulic components 07 Single circuit buffer tank: Water filter: Paddle-type flow switch: Expansion tank: Water system pressure switch: Regulating valves: Ventilation: The buffer tank primarily serves to increase the water volume in the hydraulic system in order to ensure a minimum runtime of the compressors and to prevent unnecessarily frequent on and off switching of the compressors. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. PR-2014-0112-GB Subject to modifications R2-02/2017 35
07 Charging and draining: Plate Heat Exchanger Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. The plate heat exchanger is used in a hydraulic plant as system separation. Reasons for the use of a plate heat exchanger could be: Separation between water-glycol circuit and water circuit Different temperature ranges and protection of a circuit against too high or too low temperatures Different pressure ranges and protection of a circuit against too high pressure Functioning as hydraulic switch External enabling device: Pump release: Error messaging: Control and regulation The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity of the unit and the associated water temperature may only be controlled with the internal unit controls. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After successful release, the unit switches the pump on and checks the current with an internal differential pressure switch and additionally with a paddle-type flow switch mounted on-site. As soon as a stable water flow is ensured, the water temperature is measured and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. After reaching the setpoint, the first compressor switches off. Additional compressors are switched off or on depending on the temperature change. The water pumps remain in continuous operation so that the plant can perform readings of the current water temperature in the system. After switching the unit off with the remote ON/OFF contact, the compressors are driven down and then switched off. The pump is switched off after the expiration of a programmed delay period. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. Both the water pump in the primary as well as in the secondary circuit can be operated with the enabling contact. Both pumps do not have to be in operation simultaneously. If the internal pump ON/OFF contact is employed, the unit can embed the pumps in the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. 36 PR-2014-0112-GB Subject to modifications R2-02/2017
Frost protection 07 If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. All components installed outdoors are, in this case, protected from freezing with a water-glycol mixture. Since a plate heat exchanger is employed as a system separation, filling the entire plant with anti-freeze is not required. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 37
07 Geko Geko Geko Geko Geko Unit Buffer tank Plate Heat Exchanger Primary page Secondary side Geko Geko 38 PR-2014-0112-GB Subject to modifications R2-02/2017
Sequence control gear of chiller/heat pump with dual circuit buffer tank and extensive system hydraulics 08 Area of application Generation of cold or warm water for comfort air conditioning or for process applications. The consumer network and the plant network can take on complex forms with the deployment of a dual circuit buffer tank system, where however important prerequisites must be satisfied. Sequencer Unit n Consumers Unit 2 Unit 1 Buffer tank Plant circuit Consumer circuit Functional principle of the hydraulics In this case, several units are switched in sequence in order to render the required total performance or to build a redundant system. The units can have various different power ratings. Every unit must have its own pump. For released units, the medium flows from the buffer tank to the water pump in the unit. The medium is chilled or warmed up for the required load reduction. The chilled/warm water now once again flows into the buffer tank. In case there are no requirements on chilled/warm water, the buffer tank guarantees the minimum runtime of the compressors. A constant water volume flow through the unit is guaranteed with the dual circuit buffer tank. The consumer circuit can be designed in any number of complex forms. This includes e.g.: Employment of speed-regulated pumps Employment of 2-way or 3-way valves Consumer circuits in different temperature ranges. Consumer circuits with various power capacities and water/volume flows No influence on the plant circuit can arise and a constant water quantity to the unit is guaranteed at all times. PR-2014-0112-GB Subject to modifications R2-02/2017 39
08 Dual circuit buffer tank Water filter: Paddle-type flow switch: Expansion tank: Water system pressure switch: Important hydraulic components The dual circuit buffer tank fulfills the following functions: Assurance of the entire minimum system contents. The minimum runtimes of the compressors are observed and unnecessarily frequent compressor switch on and off is prevented. Hydraulic switch for the separation of plant and consumer circuits Guarantee of a thermal stratification within the container Standing buffer tanks must be used for this purpose. The chilled water supply in the plant circuit and the chilled water inlet in the consumer circuit must be attached at the lower connections of the buffer tank. In order to determine the minimum system content of the unit, only the volume of the buffer tank and the volume of the piping between device and buffer tank may be used. However, the volume of the consumer circuit is not taken into account. Dual circuit buffer tanks for chillers are characterized by their special design whose structure favors chilled-water stratification. Perforated perfusion pipes or perforated separation plates are used in the upper and lower area of the tank. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. 40 PR-2014-0112-GB Subject to modifications R2-02/2017
Regulating valves: Ventilation: Non-return valves: Charging and draining: 08 In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. The deployment of several pumps may require the use of non-return valves in order to guarantee the correct flow direction of the heat transfer medium. This is the only way to guarantee the faultless functioning of the hydraulic system in all operating states. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. Control and regulation Sequential switching: External enabling of the unit: Pump enabling: In order to ensure an optimal management of the units relatively easily, a sequence control unit (sequencer) is available for such applications. Up to five units can be operated with this unit. The water inlet and water outlet temperature serves as the controlled variable that is measured in the common collecting pipe line of all units. In order for the sequencer to communicate with the units, every unit must be furnished with a Modbus interface. Now only the sequencer is accessed for all additional management activities. It is not necessary to control every unit individually. The unit must be enabled with the external floating contact of the sequencer. After being enabled with the remote ON/OFF contact of the sequencer, a data exchange with the connected units takes place with a bus signal. The unit with the fewest operating hours is given priority. As soon as a unit receives a command from the sequencer, the unit switches on the water pump assigned to it. After the expiration of the pump lead time, the first compressor of the unit goes into operation. Depending on the requirements and the associated setpoint deviation from the preset water temperature, additional compressors of the same unit or of the next unit go into operation, depending on the settings in the sequencer. If the compressor of the next unit is requested, it also switches its pump on beforehand. When the water temperature drops, the compressor and the pumps successively switch off. Only the pump of the last still running unit continues to operate in order to continually provide the temperature sensor of the sequencer with the current water temperature. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. PR-2014-0112-GB Subject to modifications R2-02/2017 41
08 Alarm signal: A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. Frost protection Remember: If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. 42 PR-2014-0112-GB Subject to modifications R2-02/2017
08 Unit n Unit 2 Unit 1 Sequencer Buffer tank Plant circuit Consumer circuit Consumers PR-2014-0112-GB Subject to modifications R2-02/2017 43
09 Chiller, water-cooled plant, integration of a heat-rejection system Area of application Heat-rejection circuits for water-cooled units that are exclusively employed in the warm season for generating chilled water for comfort air conditioning or for process applications. Heat-rejection system Unit Chilled-water circuit Functional principle of the hydraulics When the unit is enabled, the medium flows to the water pump into the unit. At the required load reduction, the medium takes up the waste heat and flows on to the heat-rejection system where the heat is returned to the ambient air. Important hydraulic components Water filter: Expansion vessel: Ventilation: Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. 44 PR-2014-0112-GB Subject to modifications R2-02/2017
Charging and draining: 09 Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. Control and regulation For water-cooled units, it is necessary to remove non-required heat from the cooling process and conduct it to the outdoor air. The operating limits must be observed for the reliable operation of the unit. The corresponding operating limits are provided in the technical documentation of the unit. Pump enabling: It is necessary to regulate the power of the dry cooler in order to observe the operating limits of the unit. It is recommended to regulate the speed of the fan motor depending on the dry cooler water discharge temperatures from the dry cooler. This ensures optimal heat-rejection water temperatures and constant operating conditions throughout the year. In order to achieve an optimal energy efficiency of the unit, the cooling water temperature must be kept as low as possible within the operating limits. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as the pump switch-off when turning off the compressors, is taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. Frost protection In order to protect the heat-rejection circuit from frost, the employment of a water/ glycol mixture is definitely required. DencoHappel recommends to use at least 30% ethylene glycol. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 45
09 Heat-rejection system Unit Chilled Water Circuit 46 PR-2014-0112-GB Subject to modifications R2-02/2017
Chiller, water-cooled plant, integration in the heat-rejection system with cold weather start control for all-year operation 10 Area of application Heat-rejection circuit for water-cooled units that is employed throughout the year for the generation of chilled water for comfort air conditioning or for process applications. Heat-rejection system Unit Chilled-water circuit Functional principle of the hydraulics When the unit is enabled, the medium flows to the water pump into the unit. At the required load reduction, the medium takes up the waste heat and flows on to the heat-rejection system where the heat is returned to the ambient air. When the condensation pressure is too low, the 3-way valve conducts the medium once again into the condenser to increase the condensation pressure. Operation within the permissible condensation pressure is thereby guaranteed throughout the year. Important hydraulic components Water filter: Expansion vessel: Ventilation: Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. PR-2014-0112-GB Subject to modifications R2-02/2017 47
10 Charging and draining: Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. Control and regulation Pump enabling: For water-cooled units, it is necessary to remove non-required heat from the cooling process and conduct it to the outdoor air. The operating limits must be observed for the reliable operation of the unit. The corresponding operating limits are provided in the technical documentation of the unit. The pump P2 is activated in parallel for requested compressor operation. As soon as the setpoint temperature is achieved and all compressors are disabled, the pump P2 is also switched off. All-year operating mode is required for this version. For this reason, the heat-rejection circuit is furnished with a cold-weather start control in the form of a 3-way valve (MV1). The 3-way valve is actuated by a 0-10 V signal directly from the unit, depending on the condensation pressure. This method ensures the observance of the minimum water temperature also at very low outdoor air temperatures. When the condensation pressure is too low, connection B of the 3-way valve (MV1) opens. The temperature of the inlet medium thereby increases in the condenser of the unit and the condensation pressure rises. The unit works within the range of application. As soon as the condensation pressure of the unit has reached the upper limit value, the connection B of the 3-way valve is once again slowly closed. When the heat-rejection circuit has achieved a required high temperature, as a rule the system is regulated only via the fan control of the heat-rejection system. The power of the heat-rejection system is additionally controlled by the speed of the fan motor, depending on the cooling water discharge temperatures from the dry cooler. This ensures optimal heat-rejection water temperatures and constant operating conditions throughout the year. In order to achieve an optimal energy efficiency of the unit, the cooling water temperature must be kept as low as possible within the operating limits. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. If the internal pump ON/OFF contact is used, the unit can embed the pumps into the internal control system. The required pump leading and overrun times, as well as the pump switch-off when turning off the compressors, is taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. 48 PR-2014-0112-GB Subject to modifications R2-02/2017
Frost protection 10 In order to protect the heat-rejection circuit from frost, the employment of a water/ glycol mixture is definitely required. DencoHappel recommends to use at least 30% ethylene glycol. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 49
10 Heat-rejection system Unit Chilled Water Circuit 50 PR-2014-0112-GB Subject to modifications R2-02/2017
11 Chiller, water-cooled plant, with heat-rejection system and free cooling function Area of application Generation of chilled water for comfort air conditioning or process applications. In this case, the chilling unit is water-cooled and must be set up within a building. A heat-rejection system is employed for heat dissipation to achieve a free cooling function at low outside temperatures. This provides an energy-saving operation for yearround cooling demands. Heat-rejection Plate heat exchanger Primary page Secondary side Unit Heat-rejection circuit Producer circuit Consumer circuit Functional principle of the hydraulics The following operating modes are possible for this plant system: Unit operation (as water-cooled chiller) Free cooling operation Unit operation in connection with the pumps P1 and P2 When the unit is enabled, the pump P1 supplies the medium from the buffer tank in the unit. The medium is cooled down in the evaporator and then once again flows back into the buffer tank. If there is no chilled water requirement from the consumer, the buffer tank ensures a minimum runtime of the compressors. The dual circuit buffer tank maintains a constant water volume flow into the unit. The consumer circuit can be designed in any number of complex forms. This includes e.g.: Employment of speed-regulated pumps Employment of 2-way or 3-way valves Consumer circuits in different temperature ranges. PR-2014-0112-GB Subject to modifications R2-02/2017 51
11 Consumer circuits with various power capacities and water/volume flows The plant circuit is not influenced and the water quantity through the unit is constant at all times. A water-glycol mixture must be employed as the medium in the heat-rejection circuit. When enabled, pump P2 supplies the medium through the condenser of the unit where the waste heat is taken up. At sufficiently high condensation pressure, the medium continues to be transported to the heat-rejection system in order for the waste heat to be conducted into the ambient air. The 3-way valve MV1 ensures the observance of the operating limits of the unit in the heat-rejection circuit. When the condensation pressure is too low, the 3-way valve MV1 conducts the medium via a bypass once again into the condenser. The temperature of the medium thereby continues to rise, which in turn also continues to increase the condensation pressure. Operation within the permissible condensation pressure is thereby guaranteed throughout the year. The 3-way valve MV1 is likewise necessary for the switchover from free cooling operation to unit operation, because the medium temperature lies below the application range of the unit. Without a 3-way valve, the unit would break down. Free cooling operation with a heat-rejection system in connection with the pumps P3 and P4 For free cooling operation, the pump P3 supplies the medium from the buffer tank through the secondary side of the plate heat exchanger. The medium is cooled down there and then once again flows back in the buffer tank. The pump P4 supplies the medium through the primary side of the plate heat exchanger where the heat is taken up from the cooling process. The heated medium continues to flow to the heat-rejection system in order to deliver the waste heat into the ambient air. Important hydraulic components Dual circuit buffer tank Water filter: The dual circuit buffer tank fulfills the following functions: Assurance of the entire minimum system contents. The minimum runtimes of the compressors are observed and unnecessarily frequent compressor switch on and off is prevented. Hydraulic switch for the separation of plant and consumer circuits Guarantee of a thermal stratification within the container Standing buffer tanks must be used for this purpose. The chilled water supply in the plant circuit and the chilled water inlet in the consumer circuit must be attached at the lower connections of the buffer tank. In order to determine the minimum system content of the unit, only the volume of the buffer tank and the volume of the piping between device and buffer tank may be used. However, the volume of the consumer circuit is not taken into account. Dual circuit buffer tanks for chillers are characterized by their special design whose structure favors chilled-water stratification. Perforated perfusion pipes or perforated separation plates are used in the upper and lower area of the tank. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. 52 PR-2014-0112-GB Subject to modifications R2-02/2017
Paddle-type flow switch: Expansion tank: Water system pressure switch: Regulating valves: Ventilation: Non-return valves: Charging and draining: Plate Heat Exchangers: 11 The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. The unit control system processes the falling system pressure, stops the unit and the pump and prevents expensive plant failures. In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. The deployment of several pumps may require the use of non-return valves in order to guarantee the correct flow direction of the heat transfer medium. This is the only way to guarantee the faultless functioning of the hydraulic system in all operating states. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. The plate heat exchanger is used in a hydraulic plant as system separation. Reasons for the use of a plate heat exchanger could be: Separation between water-glycol circuit and water circuit Different temperature ranges and protection of a circuit against too high or too low temperatures Different pressure ranges and protection of a circuit against too high pressure Functioning as hydraulic switch PR-2014-0112-GB Subject to modifications R2-02/2017 53
11 Control and regulation Unit operation in connection with the pumps P1 and P2 The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity of the unit and the associated water temperature may only be controlled with the internal unit controls. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After successful release, the unit switches the pump P1 on and checks the current with an internal differential pressure switch and additionally with a paddle-type flow switch mounted on-site. As soon as a stable water flow is ensured, the water temperature is measured and compared with the preset setpoint. Depending on setpoint deviation, the individual compressors are switched on or off. The pump P2 is activated in parallel for requested compressor operation. As soon as the setpoint temperature is achieved and all compressors are disabled, the pump P2 is also switched off. On continued active unit release, the water pump P1 continuously remains in operation to record the water temperatures in the system. The pumps P3 and P4 for the free cooling operation remain OFF. The heat removed from the cooling process in the heat-rejection circuit is conducted off into the outdoor air. The operating limits must be observed for the reliable operation of the unit. These are provided in the technical documentation of the unit. The heat-rejection circuit is furnished with a cold weather start control, in the form of a 3-way valve (MV1). The 3-way valve is actuated by a 0-10 V signal directly from the unit, depending on the condensation pressure. The water temperature in the heat-rejection circuit can thereby be ensured even after switchover between free cooling operation and unit operation. When the condensation pressure is too low, connection B of the 3-way valve (MV1) opens. The temperature of the inlet medium thereby increases in the condenser of the unit and the condensation pressure rises. The unit works within the range of application. As soon as the condensation pressure of the unit has reached the upper limit value, the connection B of the 3-way valve is once again slowly closed. When the heat-rejection circuit has achieved a required high temperature, as a rule the system is regulated only via the fan control of the heat-rejection system. The power of the heat-rejection system is additionally controlled by the speed of the fan motor, depending on the cooling water discharge temperatures from the heatrejection unit. This ensures optimal heat-rejection water temperatures and constant operating conditions throughout the year. In order to achieve an optimal energy efficiency of the unit, the cooling water temperature must be kept as low as possible within the operating limits. Pump release: After unit switch-off or switchover to the free cooling operation, the compressor is driven down and switched off. The pumps are switched off after the expiration of a programmed delay period. The on-site pump must be enabled with the pump ON/OFF contacts on the unit. In case the unit is not standardly supplied with pump ON/OFF contacts, then these can be provided as an option. If the internal pump ON/OFF contact is employed, the unit can embed the pumps in the internal control system. The required pump leading and overrun times, as well as pump switch-off when the unit is turned off, are taken into consideration by the internal regulation. Furthermore, additional energy-saving functions can be used. If the unit does not have an integrated water pump, no voltage supply is available at the unit for the water pumps installed on-site. The on-site pumps must therefore be provided with voltage. 54 PR-2014-0112-GB Subject to modifications R2-02/2017
11 Free cooling operation with a heat-rejection system in connection with the pumps P3 and P4 An external control with the following requirements is needed for the management of free-cooling operation: Switch-off of unit operation Actuation of the pumps P3 and P4 Actuation of the fans of the heat-rejection unit with a changed setpoint Actuation of the 3-way valve MV2 The change-over point between free cooling operation and unit operation must be precisely determined on the basis of the system configuration, in order to guarantee the required cooling needs in free cooling operation. Frequently switching between unit operation and free cooling operation should be especially avoided in seasons with strongly fluctuating daily temperatures. The switching hysteresis must be set accordingly high. The delay period of the pump P1 must be taken into consideration for the switchover from unit operation to free cooling operation. After release of the pumps P3 and P4, the fans of the heat-rejection system must be controlled depending on the medium outlet temperature of the heat-rejection unit. Make sure that the chilled water temperature is controlled for free cooling operation, for instance between +4 to +10 C, whereas for unit operation the heat-rejection water temperature must be regulated between +25 to +30 C. In order to avoid frost damages at very low outside temperatures on the secondary side of the plate heat exchanger, the 3-way valve MV2 must be installed. The control must ensure that the primary side inlet temperatures in the plate heat exchanger do not fall below +2 C. Frost protection In order to protect the heat-rejection circuit from frost, the employment of a waterglycol mixture is definitely required. DencoHappel recommends to use at least 30% ethylene glycol. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (Data & Facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 55
11 Heat-rejection circuit Heat-rejection Plate heat exchanger Primary page Secondary side Unit Buffer tank Producer circuit Consumer circuit 56 PR-2014-0112-GB Subject to modifications R2-02/2017
12 Chiller, air-cooled, integration of desuperheater for heat recovery Area of application If emphasis is also put on heat recovery in addition to the generation of chilled water, a unit with integrated desuperheater is a good opportunity to reduce operating costs for the production of warm water. Unit Chilled-water circuit Fresh water outlet Auxiliary heating Desuperheater circuit Combi storage tank E heating Fresh water inlet Functional principle of the hydraulics As soon as at least one compressor of the unit is running for the generation of chilled water, warm water can be produced for comfort or process applications via the desuperheater which is integrated in the unit. Consequently, the pump P1 should only be enabled with an activated compressor to avoid causing unnecessary energy costs. For the released pump P1, the medium flows through the water pump to the desuperheater of the unit. If the compressor is running, the medium is heated and can be made available for a heating process. For the desuperheater there are operating limits which must be maintained. The medium discharge temperature from the desuperheater must not fall below 30 C. In order to ensure this, a 3-way valve must be used. Important hydraulic components Water filter: Expansion tank: Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compen- PR-2014-0112-GB Subject to modifications R2-02/2017 57
12 Regulating valves: Ventilation: Charging and draining: Combi storage tank: sates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. In order to ensure correct operating conditions for the entire plant, the pump and plant characteristics curve have to be matched with one another. If a pump with a variable pump characteristics curve is not available, regulating valves must be used. These valves are used for rebalancing the water pumps and consumers with each other. In plants with only one consumer, the water flow rate can be adjusted. Hydraulic rebalancing is used in plants with multiple consumers for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. The combi storage tank is a drinking water heater for which different heat sources can be used to heat up drinking water. Since the maximum attainable discharge temperature from the desuperheater does not exceed 60, only combi storage tanks with a large internal heat exchanger should be used to operate the system as efficiently as possible. To ensure drinking water hygiene, the relevant basic standards and national supplementary standards must be considered and strictly adhered to. Therefore, it must also be possible to thermally disinfect the combi storage tank through corresponding heating. For this purpose the following components can be used: Additional heat exchanger, heater supported Electric heating rod Control and regulation As soon as one of the compressors is running, the desuperheater can be used for heat recovery. The enabling of pump P1 should be performed via the operating status contact of the compressors and via an enabling contact of the heating request on-site. To ensure an operation within the operating limits, a 3-way valve is used which ensures a minimum discharge temperature of 30 C from the desuperheater. As alternative, an inverter controlled pump can be used which regulates the medium volume flow via the desuperheater in such a way that this requirement is observed. 58 PR-2014-0112-GB Subject to modifications R2-02/2017
Frost protection 12 Remember: If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 59
12 Unit Desuperheater circuit Chilled-water circuit Combi storage tank Fresh water inlet Auxiliary heating E heating Fresh water outlet 60 PR-2014-0112-GB Subject to modifications R2-02/2017
13 Chiller, water-cooled plant, with heat recovery and heatrejection system Area of application Heat-rejection circuit with heat recovery for water-cooled units which are used for generating chilled or warm water for comfort air conditioning or for process applications. Heat-rejection system Unit Chilled-water circuit Plate Heat Exchanger Buffer tank Primary page Secondary side Functional principle of the hydraulics If a compressor is operating and produces waste heat, the pump P1 is also operating and transports the water-glycol mixture through the condenser of the unit where the waste heat is taken in. The heated water-glycol mixture is directed through the primary side of a plate heat exchanger. If necessary, the heat is transferred to a secondary sided water circuit and stored in a buffer tank. When the temperature of the water-glycol mixture is too low, the 3-way valve MV1 conducts the water-glycol mixture back into the condenser which causes another rise in temperature. If the allowable temperature of the water-glycol mixture is reached, the 3-way valve MV1 opens, adds chilled water-glycol mixture from the heat-rejection system and achieves an operation within the allowable operating limits. Important hydraulic components Water filter: Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. PR-2014-0112-GB Subject to modifications R2-02/2017 61
13 Expansion tank: Ventilation: Charging and draining: Buffer tank of heat recovery Plate Heat Exchangers: The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. In the field of heat recovery it is recommended to use a buffer tank. Thus, transition periods in which heat is required during inactive heat recovery are well compensated. The plate heat exchanger is used in a hydraulic plant as system separation. Reasons for the use of a plate heat exchanger could be: Separation between water-glycol circuit and water circuit Different temperature ranges and protection of a circuit against too high or too low temperatures Different pressure ranges and protection of a circuit against too high pressure Functioning as hydraulic switch Control and regulation For water-cooled units, it is necessary to remove heat from the cooling process. The heat coming from the condenser of the unit can be used for other processes or can be given off to the outside air. The operating limits must be observed for the reliable operation of the unit. The corresponding operating limits are provided in the technical documentation of the unit. In this case, heat recovery is possible and therefore a distinction is made between: Cooling operation without heat recovery Cooling operation with heat recovery Cooling operation without heat recovery In this operating mode, heat recovery is not required. The unit is to be operated as efficiently as possible. In order to achieve this, the 3-way valve MV1 is to be regulated so that the lowest possible cooling water inlet temperature T1 is ensured in the condenser, within the operating limit. The pump P1 is activated in parallel for requested compressor operation. The 3-way valve MV1 controls the minimum medium inlet temperature T1 in the condenser, depending on the water volume flow. Thus, the minimum medium discharge temperature from the condenser can be ensured and optimal conditions for an economic compressor operation are created. If the medium inlet temperature T1 exceeds the minimum allowable temperature, the 3-way valve MV1 opens the connection A and uses the heat-rejection system to dissipate excessive heat. 62 PR-2014-0112-GB Subject to modifications R2-02/2017
13 The power of the heat-rejection system is controlled by the speed of the fan motor, depending on the medium discharge temperature T4 from the heat-rejection unit. This ensures optimal heat-rejection water temperatures and constant operating conditions within the operating limits of the unit. The setpoint of the medium discharge temperature T4 corresponds to the minimum medium discharge temperature in the condenser, considering the water volume flow. Cooling operation with heat recovery In this operating mode, the heat recovery is required and the transmission of heat via the plate heat exchanger should be as efficient as possible. In order to achieve this, the 3-way valve MV1 is to be regulated so that the highest possible cooling water inlet temperature T1 is ensured in the condenser, within the operating limit. The pump P1 is activated in parallel for requested compressor operation. The 3-way valve MV1 controls the maximum medium inlet temperature T1 in the condenser, depending on the water volume flow. Therefore, optimal conditions for the heat recovery are created. If the water temperature T3, measured in the buffer tank, is lower than the medium temperature T2 coming from the condenser, pump P2 is activated and heat recovery takes place. The pump P2 is deactivated as soon as the water temperature T3 in the buffer tank exceeds the water/glycol temperature T2 coming from the condenser. This can be the case if the load request of the unit decreases. If the medium inlet temperature T1 exceeds the maximum allowable temperature, since the heat demand of the heat recovery is reduced, the 3-way valve MV1 opens the connection A and ensures a release of the non-required heat via the heat-rejection system. The power of the heat-rejection system is controlled by the speed of the fan motor, depending on the medium discharge temperature T4 from the heat-rejection unit. This ensures optimal heat-rejection water temperatures for heat recovery and constant operating conditions within the operating limits of the unit. The setpoint of the medium discharge temperature T4 corresponds in this operating mode with heat recovery to the maximum medium discharge temperature in the condenser, considering the water volume flow. PR-2014-0112-GB Subject to modifications R2-02/2017 63
13 Frost protection In order to protect the heat-rejection circuit from frost, the employment of a water/ glycol mixture is definitely required. DencoHappel recommends to use at least 30% ethylene glycol. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. 64 PR-2014-0112-GB Subject to modifications R2-02/2017
13 Heat-rejection system Chilled-water circuit Buffer tank Unit Plate Heat Exchanger Secondary side Primary page PR-2014-0112-GB Subject to modifications R2-02/2017 65
14 Cold/warm water generator with variable-speed pump, singlecircuit buffer tank and 2-way valves (VPS A-Control) Area of application Generation of cold or hot water for comfort air conditioning or for process applications. The consumer network is easily formed and the consumers are equipped with 2-way valves. By the use of a variable-speed pump, the hydraulic system can be planned securely and in an energy saving way. p DP2 Unit Buffer tank P P P P T DP1 p P V1 FL T Advantages of a variable-speed pump By the deployment of variable-speed pumps with the correct hydraulic integration of the device, many crucial advantages result compared to pumps without speed control: The maximum rotational speed of the pump is set after pressure loss in the hydraulic network. The oversizing of a pump with fixed rotational speed and the associated high power consumption is precluded. Es is important to create an exact computation of the piping in order to adapt the speed-controlled pump to the plant characteristic curve and to ensure a correct control system. Costly and energy-destroying control valves can be done without. Constant control of the water outlet temperature in stationary operation High energy-saving potential at full and partial load operation as well as also in stand-by operation Longer pump lifetime Lower noise emission 66 PR-2014-0112-GB Subject to modifications R2-02/2017
14 In full-load operation, an energy savings potential results, since the pump adapts the rotational speed to the actual demand and the pressure loss in the system. For pumps without speed control, the superfluous energy must be compensated by control valves. In partial-load mode, the reduced rotational speed lowers the air flow, since the maximum air flow is not required in partial-load mode. Depending on application case, the partial-load mode of the device with up to 97% of the time once again reflects the largest portion the operating time The water-air flow is reduced to 50% of the maximum volume of water. The system temperatures are still recorded reliably and energy saving. For systems without speed control, the pump also works during stand-by operation at maximum rotational speed and power consumption. The theoretical pump characteristics at speed change as follows: The pump feed rate behaves proportional to the change in pump speed. A reduction the rotational speed by 50% therefore leads to a halving of the pump feed rate. The pump lift behaves proportional to the square of the change of the pump speed. Therefore leads a reduction the rotational speed by 50% to a reduction of the pump lift by 25%. The power demand the pump behaves proportional to the third potential of the change of the pump speed. Therefore a reduction the rotational speed by 50% leads to a reduction the power consumption to 12.5%. The energy savings potential decisively depends on the following factors: Design and pressure losses of the hydraulic network Load acceptance of the consumer Operating and stand-by time of the device Design of the device for the required demand Functional principle of the hydraulics For released units, the medium flows from the buffer tank to the water pump in the unit. The medium is chilled or warmed up for the required load reduction. The cold/ hot water now flows over the consumers and is warmed or cooled down once again. In this case, it can be about consumers of the same or unequal power consumption at identical water temperatures. The required volume of water must be individually adjusted for every consumer with control valves, only so can the respective performance be ensured at full load. The power control of every consumer takes place by 2-way valves. At partial load, the changing pressure losses is compensated by the speed-controlled pump. For fault-free operation of the device, a minimum water-air flow through the heat exchanger of the device is required. To ensure this, the bypass valve V1 is employed. Is the minimum water flow over the heat exchanger not achieved, the bypass valve V1 opens and thereby ensures fault-free operation. Important hydraulic components One cycle buffer tank The buffer tank primarily serves to increase the water volume in the hydraulic system in order to ensure a minimum runtime of the compressors and to prevent unnecessarily frequent on and off switching of the compressors. PR-2014-0112-GB Subject to modifications R2-02/2017 67
14 Water filter: Paddle-type flow switch Expansion tank: Water system pressure switch: Regulating valves: Ventilation: Charging and draining: Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. A falling system pressure is processed in the control system of the device, then at of this malfunction stops both the unit as well as also the pump and prevents cost intensive plant breakdowns. Hydraulic rebalancing is used in plants with multiple consumers of different power ratings for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. Control and regulation External enabling device: The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity control of the device and the associated control system of the water temperature may only take place with the internal control of the device. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. 68 PR-2014-0112-GB Subject to modifications R2-02/2017
Pump release: Differential pressure over consumers (pressure sensor DP2): Differential pressure over the heat exchanger of the device (pressure sensor DP1): Bypass valve V1: Error messaging: 14 After completed release, the unit the speed-controlled pump P1 switches with a specified start rotational speed, examines the air flow with the internal differential pressure switch and additionally with the on-site mounted paddle-type flow switch. As soon as a stable water flow is ensured, the water outlet temperature is recorded and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. In addition, the controller of the device continually records the differential pressure over the most unfavorable consumers (pressure transducer DP2) and also the differential pressure over the heat exchanger of the device (pressure transducer DP1), in order to regulate the rotational speed of the pump or to control the bypass valve V1. The position of the most unfavorable consumer should be determined by the computation of piping. As control variable for the speed control of the pump, the differential pressure of the consumer lying farthest removed and in the most unfavorable pipe section is used. Which pipe section and consumers it is thereby about, must be taken from the piping computation. The differential pressure of the consumer network minimum and maximum limit values must be entered in the controller of the device. Within these limit values, the rotational speed of the pump remains unchanged. If the differential pressure increases above the maximum limit value because individual consumers close their valves, the rotational speed of the pump is reduced so that the differential pressure is once again within the limit values. If the differential pressure decreases below the minimum limit value because individual consumers open their valves, the rotational speed of the pump is increases so that the differential pressure is once again within the limit values. Since the plant characteristics is variable in certain limits by the 2-way valves to the consumers and by the speed-controlled pump, the differential pressure over the heat exchanger of the device is monitored by the pressure differential sensor DP1. In order to avoid operational breakdowns of the device, it is important to always promote a minimum water flow over the heat exchanger. As soon as the limit value for the minimum water flow is undershot, the rotational speed the pump increases and a bypass valve is opened in order to increase the differential pressure and thereby the water flow over the exchanger of the device. If the differential pressure over the heat exchanger is once again within of the required limit value, the rotational speed of the pump is reduced. The bypass valve is slowly closed. The bypass valve serves the assurance of a minimum water volumetric flow over the heat exchanger of the device when there is only little or no load and a large number of 2-valves are closed. In order to make a correct adjustment of the bypass line, it is important to only use the bypass valve in connection with a regulating valve. This is the only possibility of regulating the bypass air flow for an energy-saving operating mode. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. PR-2014-0112-GB Subject to modifications R2-02/2017 69
14 Frost protection Remember: If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. 70 PR-2014-0112-GB Subject to modifications R2-02/2017
14 p DP2 Unit p DP 1 FL T P T P P P P Buffer tank V1 PR-2014-0112-GB Subject to modifications R2-02/2017 71
15 Cold-/warm water generators with variable speed pumps in primarily and secondary circuits (VPS D-Control) Area of application Generation of cold or hot water for comfort air conditioning or for process applications. The consumer network can be made arbitrarily complex. Both on the primarily as well as also on the secondary side, speed-controlled pumps are employed. With the use of variable speed pumps, primarily and secondary circuits can be planned securely and in an energy saving manner. Consumers T T T T T T P P P P P P P2-P4 AB B A T2 Unit Buffer tank P P P P T1 T DT P P1 FL T Advantages of a variable-speed pump By the deployment of variable-speed pumps with the correct hydraulic integration of the device, many crucial advantages result compared to pumps without speed control: The maximum rotational speed of the pump is set after pressure loss in the hydraulic network. The oversizing of a pump with fixed rotational speed and the associated high power consumption is precluded. It is important to create an exact computation of the piping in order to adapt the speed-controlled pump to the plant characteristic curve and to ensure a correct control system. Costly and energy-destroying control valves can be done without. Constant control of the water outlet temperature in stationary operation High energy-saving potential at full and partial load operation as well as also in stand-by operation Longer pump lifetime Lower noise emission 72 PR-2014-0112-GB Subject to modifications R2-02/2017
15 In full-load operation, an energy savings potential results, since the pump adapts the rotational speed to the actual demand and the pressure loss in the system. For pumps without speed control, the superfluous energy must be compensated by control valves. In partial-load mode, the reduced rotational speed lowers the air flow, since the maximum air flow is not required in partial-load mode. Depending on application case, the partial-load mode of the device with up to 97% of the time once again reflects the largest portion the operating time During of the stand-by-facility, if the system temperature is achieved, the pump controls down to the minimum possible rotational speed. The water-air flow is reduced to 50% of the maximum volume of water. The system temperatures are still recorded reliably and energy saving. For systems without speed control, the pump also works during stand-by operation at maximum rotational speed and power consumption. The theoretical pump characteristics at speed change as follows: The pump feed rate behaves proportional to the change in pump speed. A reduction the rotational speed by 50% therefore leads to a halving of the pump feed rate. The pump lift behaves proportional to the square of the change of the pump speed. Therefore leads a reduction the rotational speed by 50% to a reduction of the pump lift by 25%. The power demand the pump behaves proportional to the third potential of the change of the pump speed. Therefore a reduction the rotational speed by 50% leads to a reduction the power consumption to 12.5%. The energy savings potential decisively depends on the following factors: Design and pressure losses of the hydraulic network Load acceptance of the consumer Operating and stand-by time of the device Design of the device for the required demand Functional principle of the hydraulics By the use of a bypass line in the secondary side consumer circuits, this hydraulic system is separated from the primary side generator circuit. Since the unit is in the position to demand-dependently regulate the rotational speed of the primary pump P1, speed-controlled pumps can also be employed for the on-site secondary pumps. For released units, the medium flows from the buffer tank to the water pump in the unit. On required load acceptance, the medium is refrigerated or warmed and therefore available to the secondary network with the pumps P2 to P4. If there is only a small or no cooling/heating requirement and the volume of water was thereby reduced over the secondary side consumers, the water is with a bypass line between supply line and return flow distributer once again supplied to the primary circuit. A minimum volume of water is thereby ensured with the unit. The consumer circuit can be designed in any number of complex forms. Among these are e.g. Employment of speed-regulated pumps Employment of 2-way or 3-way valves Consumer circuits in different temperature ranges. Consumer circuits with various power capacities and water/volume flows The volume of water of the primarily circuit must always be greater than the volume of water of the secondary circuit over the consumers. PR-2014-0112-GB Subject to modifications R2-02/2017 73
15 One cycle buffer tank Water filter: Paddle-type flow switch Expansion tank: Water system pressure switch: Ventilation: Charging and draining: Important hydraulic components The buffer tank primarily serves to increase the water volume in the hydraulic system in order to ensure a minimum runtime of the compressors and to prevent unnecessarily frequent on and off switching of the compressors. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. A falling system pressure is processed in the control system of the device, then at of this malfunction stops both the unit as well as also the pump and prevents cost intensive plant breakdowns. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. Control and regulation As already mentioned as the functional principle the hydraulic system, the control of the secondary circuit separated from the primary circuit must be observed. Since the unit does not perform the actuation and control of the secondary pumps P2-P4, this must be regulated on-site with the load. The control system of the primary circuit is taken over by the unit with the pump P1. 74 PR-2014-0112-GB Subject to modifications R2-02/2017
15 External enabling device: Pump release: Temperature sensor T1 and T2: The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity control of the device and the associated control system of the water temperature may only take place with the internal control of the device. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After completed release, the unit the speed-controlled pump P1 switches with a specified start rotational speed, examines the air flow with an internal differential pressure switch and additionally with the on-site mounted paddle-type flow switch. As soon as a stable water flow is ensured, the water outlet temperature is recorded and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. In addition, the controller of the device continually records the values the temperature sensor T1 and T2 and also the temperature difference with the heat exchanger of the device. The rotational speed the primary pump is determined with the values of this parameter. The sensor T1 must be assembled on-site in the water outlet line and the sensor T2 in the bypass line between the supply and return flow distributer. The rotational speed the pump P1 is corrected by analysis of this temperature sensor so that the volume of water of the primary circuit is never less than the volume of water of the secondary circuit. The presupposes that the on-site secondary pumps are designed or limited for this purpose. The speed of the primary pump P1 is regulated according to the following criteria: T1=T2 The rotational speed of the primary pump remains constant and is not corrected T1<T2 This means that the secondary volume of water is greater than the primarily volume of water. The rotational speed of the primary pump is slowly increased until T1 and T2 have the same values. For units in heat pump operation, the logic is vice versa (T1 > T2) Temperature difference over the heat exchanger of the unit (DT): The actual speed control the pump P1 takes place with the water-side temperature difference over the heat exchanger of the device. The temperature difference ΔT over the evaporator is compared at regular intervals with a reference value. The rotational speed of the primary pump P1 is regulated according to the following criteria: the rotational speed of the primary pump P1 is regulated according to the following criteria: DT HEATEXCHANGER > reference value DT HEATEXCHANGER > reference value speed of pump P1 is slowly increased speed of pump P1 is slowly decreased Especially in the partial load mode of the device, the performance of pump P1 can be adapted and energy saved. Error messaging: A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. Frost protection If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. PR-2014-0112-GB Subject to modifications R2-02/2017 75
15 Remember: If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. 76 PR-2014-0112-GB Subject to modifications R2-02/2017
15 FL T T T T T T T T P P P P P P P P P P1 P P P2-P4 AB A T1 B Unit DT Buffer tank Consumers T2 PR-2014-0112-GB Subject to modifications R2-02/2017 77
16 Cold/warm water generator with variable-speed pump and single-circuit buffer tank with 3-way valves (VPS A-Control) Area of application Generation of cold or hot water for comfort air conditioning or for process applications. The consumer network is easily formed and the consumers are equipped with 3-way valves. By the use of a variable speed pump, the hydraulic system can be planned securely and to save energy. A A A A A A A B B B B B B B AB AB AB AB AB AB AB Unit Buffer tank P P P P T DT P FL T Advantages of a variable-speed pump By the deployment of variable-speed pumps with the correct hydraulic integration of the device, many crucial advantages result compared to pumps without speed control: The maximum rotational speed of the pump is set after pressure loss in the hydraulic network. The oversizing of a pump with fixed rotational speed and the associated high power consumption is precluded. It is important to create an exact computation of the piping in order to adapt the speed-controlled pump to the plant characteristic curve and to ensure a correct control system. Costly and energy-destroying control valves can be done without. Constant control of the water outlet temperature in stationary operation High energy-saving potential at full and partial load operation as well as also in stand-by operation Longer pump lifetime Lower noise emission 78 PR-2014-0112-GB Subject to modifications R2-02/2017
16 In full-load operation, an energy savings potential results, since the pump adapts the rotational speed to the actual demand and the pressure loss in the system. For pumps without speed control, the excessive energy must be compensated by regulating valves. In partial-load mode, the reduced rotational speed lowers the air flow, since the maximum air flow is not required in partial-load mode. Depending on application case, the partial-load mode of the device with up to 97% of the time once again reflects the largest portion the operating time During of the stand-by-facility, if the system temperature is achieved, the pump controls down to the minimum possible rotational speed. The water-air flow is reduced to 50% of the maximum volume of water. The system temperatures are still recorded reliably and energy saving. For systems without speed control, the pump also works during stand-by operation at maximum rotational speed and power consumption. The theoretical pump characteristics at speed change as follows: The pump feed rate behaves proportional to the change in pump speed. A reduction the rotational speed by 50% therefore leads to a halving of the pump feed rate. The pump lift behaves proportional to the square of the change of the pump speed. Therefore leads a reduction the rotational speed by 50% to a reduction of the pump lift by 25%. The power demand the pump behaves proportional to the third potential of the change of the pump speed. Therefore a reduction the rotational speed by 50% leads to a reduction the power consumption to 12.5%. The energy savings potential decisively depends on the following factors: Design and pressure losses of the hydraulic network Load acceptance of the consumer Operating and stand-by time of the device Design of the device for the required demand Functional principle of the hydraulics For released units, the medium flows from the buffer tank to the water pump in the unit. The medium is chilled or warmed up for the required load reduction. The cold/ hot water now flows over the consumers and is warmed or cooled down once again. In this case, it can be about consumers of the same or unequal power consumption at identical water temperatures. The required volume of water must be individually adjusted for every consumer with control valves, only so can the respective performance be ensured at full load. The power control of every consumer takes place by 3-way valves. Important hydraulic components One cycle buffer tank Water filter: Paddle-type flow switch The buffer tank primarily serves to increase the water volume in the hydraulic system in order to ensure a minimum runtime of the compressors and to prevent unnecessarily frequent on and off switching of the compressors. Water filters must always be installed before the immediate entry of all water-side heat exchangers in the system. The water filter protects the heat exchanger from deposits and soiling of all kinds. For reliable protection, only use dirt traps with a mesh width of maximum 1 mm. Water filters are a prerequisite for the reliable and faultless function of the unit. The paddle-type flow switch protects the unit evaporator if there is no or inadequate water volume flow. The flow switch must be installed at the unit outlet and electrically connected to the unit, according to the wiring diagram. The flow switch acts as a safety device and not as a regular control element of the unit. The unit's remote PR-2014-0112-GB Subject to modifications R2-02/2017 79
16 ON/OFF may therefore not be switched with the flow switch. The flow switch is a prerequisite for the reliable and faultless functioning of the unit. Expansion tank: Water system pressure switch: Regulating valves: Ventilation: Charging and draining: The expansion tank is mandatory, since this hydraulic system is a closed water circulation system. The expansion tank provides a required hydraulic seal and compensates temperature-related volume changes in the hydraulic system. The entire system volume must be taken into consideration for the dimensioning of the expansion tank. If the plant configuration unit is used with a pre-integrated hydraulic module, it often contains pumps, single-circuit buffer tanks, and possibly (apart from other installations) also expansion tanks. In most cases, however, these expansion tanks are only dimensioned for the water volume of the unit and no longer suffice for the connected hydraulic circuit. The volume of the required additional expansion tank must be harmonized with the total water volume in the hydraulic system. The volume of the expansion tank integrated in the unit usually must be supplemented with an additional expansion vessel on-site. The unit is very frequently mounted on the roof of the building and thereby at the highest point of the system. If an incorrect inlet pressure is the reason for the pressure fall on the highest point of the plant, where the water pumps is often mounted, this leads to cavitation on the suction side of the pump. If cavitation is not noticed in time, water pumps and other plant components can be damaged. If units and water pumps are mounted on the highest point of the plant, then the water pressure switch of the plant should be used at all times. All units are usually equipped with an electrical input that can process the floating contact of the water pressure switch of the plant. A falling system pressure is processed in the control system of the device, then at of this malfunction stops both the unit as well as also the pump and prevents cost intensive plant breakdowns. Hydraulic rebalancing is used in plants with multiple consumers of different power ratings for regulating different volume flows or compensating different pressure drops in the pipework. Vent valves and air collector must be positioned in such a way to ensure correct venting of the hydraulic plant before the unit is commissioned for use. Air-vent valves are not considered in the schematic diagram. Filling and drain valves must be positioned in such a way that the hydraulic plant can be correctly filled and drained. Filling and drain valves are not taken into account in the schematic diagram. Control and regulation External enabling device: Pump release: The unit can be released with an external zero-voltage contact. The release-/changeover contact can be switched to outside temperature or be time-dependent. The enabling contact may not be used to control capacity or temperature. The capacity control of the device and the associated control system of the water temperature may only take place with the internal control of the device. Otherwise the consequence is a cycle operation of the compressors with too short runtimes as well as a considerably worsened energy efficiency of the overall system. After completed release, the unit the speed-controlled pump P1 switches with a specified start rotational speed, examines the air flow with the internal differential pressure switch and additionally with the on-site mounted paddle-type flow switch. As soon as a stable water flow is ensured, the water outlet temperature is recorded and compared with the preset setpoint. Depending on the extent of the deviation, the individual compressors are switched on in order to chill or heat the water to the setpoint. 80 PR-2014-0112-GB Subject to modifications R2-02/2017
Temperature difference over the heat exchanger of the unit (DT): Error messaging: 16 The actual speed control the pump P1 takes place with the water-side temperature difference over the heat exchanger of the device. The temperature difference ΔT over the evaporator is compared at regular intervals with a reference value. The rotational speed of the primary pump P1 is regulated according to the following criteria: DT HEATEXCHANGER > reference value DT HEATEXCHANGER > reference value speed of pump P1 is slowly increased speed of pump P1 is slowly decreased Especially in the partial load mode of the device, the performance of pump P1 can be adapted and energy saved. A floating contact is available in the unit for monitoring the plant. The contact closes in case of a service breakdown. Never switch the unit off with the external enabling signal, since if a break-down is recorded via the floating contact, information on the cause of the malfunction might no longer be displayed on the unit display. Furthermore, the entire unit is thereby put out of commission, even though possibly only one of several refrigeration circuits was affected. Frost protection Remember: If the pipework with circulating water is run in the outdoor area or if the pipework is not protected against frost within the building, the relevant freeze protection must be ensured. DencoHappel recommends to use at least 30% ethylene glycol. If glycol is not used as an antifreeze agent, note that you must use trace heating for the pipework and other components like expansion tank and pump that are subjected to outside temperatures below 5 C. For the water-based components in the unit, suitable options are available and provided by the factory. Additional notices for planning Every unit is subject to relevant operating limits. The following points must be considered: minimum and maximum ambient temperatures minimum and maximum water temperatures for evaporator and condenser To ensure a trouble-free operation, it is necessary to maintain the required operating limits. The technical documentations (data & facts) of each unit include diagrams of the operating limits which must be taken into account. PR-2014-0112-GB Subject to modifications R2-02/2017 81
16 B A AB A B AB Buffer tank B A AB T P P B A AB B P P T A AB P FL B A AB Unit DT B A AB 82 PR-2014-0112-GB Subject to modifications R2-02/2017
Legend _i 3-way motor valve Bypass valve / 2-way motor valve Shut-off valve Cap valve Ball valve Regulating valve Safety valve (spring-loaded) Strainer Non-return damper Pipeline compensator Expansion tank Circulating pump Circulating pump with speed regulation FL Paddle-type flow switch TS Temperature sensor sequential control T Thermometer P Pressure gauge P Pressure switch p Differential pressure sensor DT Measurement of temperature difference Pipe connection Electric line PR-2014-0112-GB Subject to modifications R2-02/2017 83
DencoHappel is a global company with expertise in air treatment, air conditioning and air filtration. Our nearest sales and service teams will be glad to discuss ideas and develop creative and effective solutions with you. www.dencohappel.com