UNT Applications. Using UNT Applications...3. Introduction Key Concepts UNT Controller Applications Fan Coil Units...

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1 Application Note Issue Date 04/17/08 Supersedes 01/11/01 APPLICATION NOTE Using...3 Introduction... 3 Key Concepts... 4 UNT Controller Applications... 4 Fan Coil Units... 8 Unit Ventilators Rooftop Units...18 Telecommunications Hut/POP Applications...20 Heat Pumps...23 Pump Lead/Lag...24 Questions Common to All Applications Controllers Configured to Function as Point Multiplexers Procedure Overview Detailed Procedures Creating a Fan Coil Application Creating a Unit Ventilator Application...34 Creating a Rooftop Unit Application...45 Creating a Telecommunications Hut/POP Application...57 Creating a Heat Pump Application...58 Creating a Pump Lead/Lag Application Completing the Common Section of UNT Application Question/Answer Paths Configuring a Controller as a Point Multiplexer Module Point Assignments and Parameters Fan Coil Units Unit Ventilators Johnson Controls, Inc. Code No. LIT Software Release 8.03

2 2 Rooftop Units...87 Telecommunications Hut/POP...91 Heat Pumps...96 Pump Lead/Lag Parameters...100

3 3 Using Introduction Unitary (UNT) controller applications are specifically designed for digital control of packaged air handling units, rooftop units, unit ventilators, fan coils, heat pumps, and other terminal units including Air Handling Units (AHUs) serving a single zone or room. These applications may be used with standalone controllers, controllers connected to the N30/N31 Supervisory Controller, controllers connected to Metasys Companion /Facilitator controllers, or controllers integrated with the Metasys Network through a Network Control Module (NCM). This document provides an overview of UNT applications and includes procedures for the creation of applications. This document describes how to: create a fan coil application create a unit ventilator application create a rooftop unit application create a Telecommunications Hut/POP (Point of Presence) application create a heat pump application create a pump lead/lag application complete the common section of UNT application question/answer paths configure a controller as a point multiplexer module

4 4 Key Concepts UNT Controller Applications Getting Started UNT controller applications are specifically designed for digital control of packaged air handling units, rooftop units, Telecommunications Hut/POPs, unit ventilators, fan coils, heat pumps, and other terminal units serving a single zone or room. These applications may be used with standalone controllers, controllers connected to Companion/Facilitator controllers or controllers integrated with the Metasys Network through a Network Control Module (NCM). When connected to the Metasys N2 Network, the controller provides all point and control information to the rest of the network. The devices communicate through the N2 Bus. For a smaller facility, the controller can stand alone in conjunction with a Zone Terminal. In all configurations, the UNT applications can configure a wide variety of single zone and room Heating, Ventilating, and Air Conditioning (HVAC) equipment. The UNT applications support up to 16 sideloops that are separate from the main control logic. See Appendix A: Sideloop Applications (LIT ) for more information. The UNT controller can control many different single zone or room applications and control strategies (Figure 1). The types of zone applications that can be controlled include: unit vent fan coil packaged rooftops Telecommunications Hut/POP heat pump generic Input/Output (I/O) The first five applications are explained in this application note. Use the table of contents to locate the specific application you are using. Note: Do not use UNT1100 Series controllers for floating or three wire actuator applications, because these actuators could compromise the service life of the UNT1100 output relays.

5 5 See the HVAC PRO User s Guide for information on HVAC PRO software. See the Unitary Controller (UNT) Technical Bulletin (LIT ) for UNT wiring and installation information. File Open New Select Existing File Central Plant Applications OEM Applications Rooftop Applications Terminal Unit Applications Generic I/O Pump Lead/Lag Control Packaged Rooftop Unit Vent Fan Coil Heat Pump Point Multiplexer CNUNTFLW Figure 1: UNT Application Configuration Paths The UNT can be pre-configured with control strategies for specific Original Equipment Manufacturer (OEM) applications. HVAC PRO software contains the configuration files to commission specific OEM applications. HVAC PRO software, which is a part of the M-Tool software package, also allows you to configure all hardware points as inputs or outputs to the N2 Network. Modes of Operation Table 1 illustrates the source of control commands for each mode of operation. Table 1: Command Source for Modes of Operation Mode of Operation N2 ZT BI Built-in HVAC PRO Software Commissioning* Occ/Unocc X X X X Standby X X X Shutdown X X X X Temp Occ/Occ Extend X X Boost X Power Fail Restart X Warmup X X X Vent X X Purge X X * Online commissioning via the Zone Bus or N2 network connection. When you exit Commissioning mode, parameters that are not saved to the controller are released immediately. Overrides to inputs, outputs, and commandable parameters are also released when commissioning is exited. Refer to Exiting Commission Mode for ASC Devices in the Commissioning a Controller chapter of the HVAC PRO User s Guide for further information.

6 6 Control Sequence Figure 2 shows the relationship of the heating (htg), economizer, and mechanical cooling (clg) output commands vs. changes in zone temperature. Increasing Output Commands 100% 0% Heating Prop Band Heating Setpoints - Occupied - Standby - Unoccupied Econ Prop Band Cooling Deadband or Alternate Cooling Deadband Cooling Setpoints - Occupied - Standby - Unoccupied Cooling Prop Band Increasing Zone Temperature GRPHUV Figure 2: Heating and Cooling Setpoints All unitary controllers use the same default zone setpoints for the Occupied, Unoccupied, and Standby modes of operation. See the default I/O point and parameter tables for each application to determine default values used to set up the base sequence of operation. Note: Standby mode only initiates when the controller is already in Unoccupied mode. Closed Loop Control The controller provides separate heating and cooling setpoints with associated proportional bands. Integration is available for heating and cooling, including economizer and mechanical cooling functions. Default Parameter The cooling deadband allows you to sequence mechanical cooling with an economizer output or overlap the two outputs. Set the cooling deadband equal to the economizer prop band to provide a sequence of free cooling and mechanical cooling without overlap. IMPORTANT: When using integration and increasing the economizer proportional band to tune the damper control, make sure that the cooling deadband is equal to the economizer proportional band.

7 7 The alternate cooling deadband allows you to decide if the mechanical cooling output should start at the cooling setpoint when free cooling is not available. By default, all zone integration timers are zero and no integration is added into the zone control process. If integration is desired, add the adjustment during commissioning only after the control process is under stable proportional control. For room control, a value of 400, equivalent to 10 minutes, is a good place to start for an integration time. A larger integration value has less effect on the control loops. If using integration, the proportional band may need to be increased for stable control. IMPORTANT: For applications that use on-off or staged outputs for heating and/or cooling, use of integration may make the loop difficult to tune. This is due to interaction with the minimum on and off timers and maximum cycles per hour. In these cases, extremely long integration times are appropriate, on the order of 600 to 1000 (15 to 25 minutes), for zone control.

8 8 Damper Logic Modes The Warmup, Vent, and Purge modes (Table 2) are available in any configuration that incorporates an outside air damper. Table 2: Damper Logic Modes Mode Warmup The Warmup mode is pre-configured in the controller, so the user is not prompted through the Question and Answer session for this feature. A Warmup cycle is initiated by an N2 or Zone Terminal command only when the controller is in Unoccupied mode. Once set to Warmup mode, systems configured with outside air dampers hold the dampers fully closed and sequence heating/cooling. The fan cycles based on the call for heating or cooling. Outside air damper operation is enabled when the system is commanded to Occupied mode. Occupied mode does not automatically initiate a disable command to Warmup, although it does disable the Warmup operation. Vent Vent mode is only initiated or ended via an N2 command. During Vent mode, systems configured with a proportional or Zone Bus output to the outside air damper hold the dampers in the fully open position until Vent mode is ended. The mechanical heating and cooling outputs operate as required. Purge Purge mode is only initiated or ended via an N2 command. During Purge mode, systems configured with a proportional or Zone Bus output to the outside air damper hold the dampers in the fully open position until Purge mode is ended. The mechanical heating and cooling outputs are shut off. Note: If you command Vent and Purge modes at the same time, the Vent mode takes priority. Vent and Purge modes do not automatically start the fan. To run the fan in Vent or Purge modes, you must first command the controller to Occupied mode. Fan Coil Units Applications A fan coil unit is a simple method of controlling an individual space. Typically used in entryways and other similar perimeter zones, fan coils consist of a fan, a heating and/or cooling coil, and a filter (Figure 3). In some cases, the unit may come with a manually adjustable outside air damper. If the unit requires an automatic outside air damper, use either the Unit Ventilator or Rooftop application.

9 9 Wall Zone Sensor Conditioned Air Fan Controller Heating and/or Cooling Coil Air Filter Return Air FANCOIL Figure 3: Typical Fan Coil Unit A controller with a wall-mounted or return air mounted sensor controls fan coil heating and cooling in sequence to achieve setpoint. Water-based fan coil systems may be arranged in a 2-, 3-, or 4-pipe configuration. These configurations require different numbers of valves and different control sequences. If the fan coil has separate heating and cooling coils, separate valves are used. When a common coil is used for heating and cooling, the supply and return piping systems affects the control method. Two Pipe Heating and Cooling Systems When a common coil provides both heating and cooling with a single valve, controller action must switch when chilled water, not hot water, is present (Figure 4). Hot or Chilled Water Supply Common Heating and Cooling Coil Hot or Chilled Water Return pipes Figure 4: Two Pipe Heating and Cooling Three Pipe Heating and Cooling Systems IMPORTANT: This application was a common piping practice in the past and is only found in retrofits. When a common coil provides both heating and cooling, two valves are required: a chilled water supply valve and a hot water supply valve (Figure 5). These valves are then modulated in sequence to control the temperature.

10 10 Hot Water Supply Chilled Water Supply Common Heating and Cooling Coil Hot and Chilled Water Return Pipes1 Figure 5: Three Pipe Heating and Cooling Four Pipe Heating and Cooling Systems IMPORTANT: This application is not common. You cannot configure an application of this type using HVAC PRO software. When a common coil provides both heating and cooling, three valves are required: a chilled water supply valve, a hot water supply valve, and a switching return valve (Figure 6). The heating and cooling valves are then modulated in sequence to control the temperature. The return valve is switched while both valves are closed. Hot Water Supply Chilled Water Supply Common Heating and Cooling Coil Hot Water Return Chilled Water Return Pipes2 Figure 6: Four Pipe Heating and Cooling Control System Fault Tolerance If the zone sensor becomes unreliable, the position of the valves is user definable from 0-100%.

11 11 Unit Ventilators Applications Unit ventilators heat, ventilate, and cool a space by introducing outside air in quantities up to 100%. They also provide the option to cool and dehumidify with a cooling coil (either chilled water or DX). Hot water, steam, or electric resistance provide heating. Valves, face and bypass dampers, or control switches/relays are used to control these sources of heat. The basic components of a unit ventilator are encased in a housing and include: a fan a motor a heating element dampers a filter outlet grilles (or diffusers) Unit ventilators are used primarily in schools, meeting rooms, offices, and other areas where the density of occupancy requires controlled ventilation. These ventilators provide sufficient heating capacity to rapidly warm up a room in the morning and to ventilate and heat as required during occupancy. In most cases, unit ventilators use additional outside air to dissipate uncontrolled heat. Figure 7, Figure 8, and Figure 9 show component placement in various American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) cycles.

12 12 Glass Conditioned Air Wall Discharge Low Limit Zone Sensor Fan Bird Screen Coil Valve Actuator Outside Air Intake Louver Air Filter Recirculated Air Intake Outside Air Damper Damper Actuator Recirculated Air Damper UNITVENT Figure 7: Component Placement for ASHRAE Cycles I and II

13 13 Glass Conditioned Air Wall Zone Sensor Fan Outside Air Intake Louver Bird Screen Coil Valve Actuator Air Filter Return Air/Mixed Air Control Recirculated Air Intake Outside Air Damper Damper Actuator Recirculated Air Damper UNITVEN2 Figure 8: Component Placement for ASHRAE Cycle III

14 14 Glass Conditioned Air Wall Discharge Low Limit Fan Bird Screen Coil Valve Actuator Zone Sensor Outside Air Intake Louver Air Filter Recirculated Air Intake Outside Air Damper Damper Actuator Recirculated Air Damper UNITVEN3 Figure 9: Component Placement for Cycle W ASHRAE Control Cycles Unit ventilators are generally controlled by one of the standard ASHRAE Control Cycles (I, II, III, or W). Variations in the amount of outside air delivered to the room determine which cycle to use. All unit manufacturers use standard ASHRAE Control Cycle designations. ASHRAE cycles I, II, III, and W allow the user to wire a fan status input to the controller. This application provides the actual status of the fan, because the controller may not have total control over the fan s operations. To prevent frozen coils, use the status of the fan to modify the control algorithm.

15 15 Cycle I ASHRAE Cycle I (Figure 10) supplies 100% outside air at all times. As the room temperature rises into the normal operating range of the zone thermostat, the outside air damper is fully opened and the return air damper is closed. The heating valve is controlled by the zone thermostat to maintain setpoint. The discharge air thermostat can override the zone thermostat action on the heating valve to open the valve to maintain a minimum discharge air temperature into the space. Open ½ Closed Room Setpoint Heating Normal Ventilation Room Temperature Outside Air (OA) Damper Valve or Face Damper Cycle1 Figure 10: ASHRAE Cycle I Cycle II A fixed minimum amount of outside air, normally 15 to 50%, is admitted during the heating and ventilating period (Figure 11). The percentage is gradually increased to 100%, if required, during the ventilating period. The heating valve and outside air dampers are operated in sequence as required to maintain space temperature. The discharge air sensor can override the zone thermostat action on the heating valve to open the valve. As the discharge temperature continues to drop, the heating goes to 100% and the Outside damper closes to prevent discharge air from dropping below a minimum temperature.

16 16 Open Room Setpoint 1/2 Minimum Closed Heating Normal Ventilation Room Temperature OA Damper Valve or Face Damper cycle2 Figure 11: ASHRAE Cycle II Cycle III In this ASHRAE cycle (Figure 12), the discharge sensor of Cycles I and II becomes a mixed air sensor by placing it in the unit ventilator airstream entering the heating source. During the heating, ventilating, and cooling stages, Cycle III supplies a variable amount of outside air as required to maintain a fixed temperature (typically 55 F) entering the heating coil. As the zone temperature rises into the normal range of the zone thermostat, ventilation dampers control the air temperature entering the heating coil at the mixed air setpoint. Space temperature is controlled by positioning the heating valve, as required. Without low limit interference, the room sensor directly controls the heating element. Open Room Setpoint OA at 50 degrees 1/2 Mix Air Control Range OA at 0 degrees Closed Heating Normal Ventilation Room Temperature OA Damper Valve or Face Damper cycle3a Figure 12: ASHRAE Cycle III

17 17 Cycle W In addition to the standard ASHRAE cycles of control, a fourth cycle, Cycle W (Figure 13), has been created. Cycle W is the same as ASHRAE Cycle II with one exception: the discharge air low limit sensor controls only the outside and recirculated air dampers. The room sensor directly controls the heating element. Open Room Setpoint 1/2 Minimum Closed Heating Required Normal Cooling Required Room Temperature OA Damper Valve or Face Damper cyclew Figure 13: Cycle W Control System Fault Tolerance The following points are useful for control system fault tolerance: If the outside air sensor is unreliable, the damper goes to 0%, cooling lockout status is off, and economizer status is off. If the zone sensor is unreliable, heating and cooling outputs are user definable. The fan goes on or stays on. If the discharge sensor is unreliable, the damper goes to minimum position if occupied and 0% if unoccupied. If warmer/cooler remote setpoint adjustments become unreliable, the controller uses the software setpoints. If heating/cooling remote setpoint adjustments become unreliable, the controller uses the software setpoints.

18 18 Rooftop Units Applications An Outside rooftop unitary equipment system cools or heats an entire zone. The complete system consists of unitary equipment, a ducted air distribution system, and a temperature control system. The equipment is generally mounted on the roof but can also be mounted on grade. When a single unit application is required, the rooftop unit and associated ductwork constitute a central station all air system. Each temperature control zone may have its own unit. Determine the control zones by using cooling and heating loads for the space served, occupancy considerations, allowable roof loads, flexibility requirements, appearance, duct-size limitations, or equipment size availability. These units also serve core areas of buildings with perimeter spaces being served by packaged terminal air conditioners (fan coil, unit ventilator, and heat pump). The rooftop unit provides standalone control of all heating, cooling, and economizer functions. The unit can heat and cool at all times with automatic changeover, regardless of the mode of operation of other spaces in the building. Night setback (unoccupied) and standby operations conserve energy when the space is unoccupied for short and long time periods. You can add an optional airflow switch to immediately shut down all heating/cooling equipment upon loss of fan airflow. Lighting integration and diagnostics for staged outputs to indicate malfunction are also provided. To save cooling energy, this application can obtain free cooling from outside air rather than starting the mechanical equipment. If required, you can readjust the cooling setpoint based on the zone humidity to save on cooling energy. (According to ASHRAE comfort zone standards, if the zone humidity is low during cooling, the zone temperature can be higher while establishing the same comfort level.)

19 19 Upgrade Information Staged heating/cooling diagnostics are supported only by controllers with A0n or later firmware. If you upgrade the controllers, the upgrade uses all existing controller parameters unless there is a newly assigned function. When doing an upgrade, the cooling lockout for staged cooling is now automatic. HVAC PRO software assigns an outside air sensor to an unused Analog Input (AI). If all AIs are used, it overwrites user-defined analog input at AI5 with an outside air sensor. This default cooling lockout value is 15.0 C (60.0 F). If you upgrade a rooftop unit that has a proportional damper, the discharge low limit proportional band has changed from a default of 1.5 C (3.0 F) to a default of C (-30.0 F). If this point has been overridden by a network device, check the override to make sure it accounts for the new value. Control System Fault Tolerance The following points are useful for control system fault tolerance: If an outside air sensor becomes unreliable, the damper goes to 0%, heating and cooling lockout status is off, and economizer status is off. If the zone sensor is unreliable, heating and cooling outputs are user selectable. The fan goes on or stays on. If a discharge sensor becomes unreliable, the damper goes to minimum position if occupied and 0% if not occupied. In the case of the zone setpoint adjusted from the zone humidity selection, if the zone humidity sensor is unreliable, the controller uses the default setpoints. In the case of the outside air enthalpy or enthalpy comparison economizer switchover selections, if the outside air or zone humidity sensor becomes unreliable, the controller uses the dry bulb temperature default for economizer switchover. If warmer/cooler remote setpoint adjustments become unreliable, the controller uses the default setpoints. If heating/cooling remote setpoint adjustments become unreliable, the controller uses the default setpoints.

20 20 Telecommunications Hut/POP Applications A Telecommunications Hut/POP (Point of Presence) unitary system controls the HVAC equipment for the zone in a telecommunications/data communications equipment hut. The huts feature redundant heating/cooling units. There are two types of Telecommunications Hut/POP applications, the Compressor Lead/Lag application and the Compressor Stage Swapping application. Compressor Lead/Lag Application The Compressor Lead/Lag application has two equal-sized units that share equal time as the lead system. The two units in combination are treated as two stages of heating or cooling, but the first stage unit is rotated based on runtime. The runtime is a configurable parameter adjustable from 0 to 1000 hours. A pushbutton connected to Binary Input (BI) 4 permits a manual changeover of the lead unit. Any changeover resets the runtime counter to zero. As the zone temperature drops below the heating setpoint, the first heat stage energizes based on the percent heating command selected during the configuration. If the zone temperature continues to drop, the second stage energizes. When the zone temperature rises, stages turn off in the reverse order (last on, first off). Each stage has a minimum on time and stage delay that must be met before the next stage energizes or turns off. As the zone temperature rises above the zone cooling setpoint and the economizer status is Off, the outside air damper is at its minimum position setting. The first stage of cooling energizes based on the percent compressor command selected during the configuration. If zone temperature continues to increase, the second stage energizes after the configurable interstage delay. The cooling stages turn off in reverse order (last on, first off). Compressor Stage Swapping Application The Compressor Stage Swapping application has two unequal-sized (one small and one large) DX compressors to control the cooling. The compressors function in three stages of cooling: the small compressor alone, the large compressor alone, and both compressors together.

21 21 As the zone temperature rises above the zone cooling setpoint and the economizer status is Off, the dampers modulate to the minimum position and the first stage energizes when the compressor command reaches 33%. When the compressor command reaches 66%, the first stage de-energizes and the second stage energizes. The first stage re-energizes when the compressor command reaches 100% and then both stages are in operation. Each stage has a minimum on time and cooling stage delay that must be met before the next stage energizes. Free Cooling To save cooling energy, the economizer allows free cooling from outside air rather than starting the mechanical equipment. The economizer status On means that free cooling is available and the dampers will modulate from 0% to 100% as the zone temperature increases. If the economizer status is On and the cooling lockout status is Off, the dampers modulate to full open. If the zone temperature continues to rise, the first cooling stage energizes and the dampers modulate closed to lengthen the on time (false loading), prevent short cycling, and facilitate the pump down cycle of the refrigeration equipment. If you change the defaults and allow free cooling and mechanical cooling simultaneously, air entering the compressor at less than 65 F can cause it to shut down, requiring a manual reset. With a proportional economizer, the system assigns a discharge air sensor to maintain the low limit logic for the economizer cycle. A reverse acting Proportional plus Integral (PI) algorithm backs off the economizer command and positions the damper to maintain the low limit setpoint. The Discharge Air Low Limit (DALL) control can override the minimum position setting if the discharge temperature continues to drop below the setpoint (e.g., freezing conditions in the outside air). If you require a minimum damper position, regardless of the DALL (e.g., if you are not in danger of freezing mechanical equipment), use the damper offset parameter that prevents the damper from going below this value during Occupied or Standby modes. The DALL setpoint automatically increases (up to 3.0 C [5.0 F]) depending on the difference between the zone temperature and the Outside Air Temperature (OAT). For example, if the outside air temperature is 20 F colder than the zone temperature, the DALL does not reset. However, if the outside air is 100 F colder than the zone, the DALL setpoint increases 3.0 C (5.0 F). If an outside air sensor is not connected or is unreliable, the DALL setpoint does not reset.

22 22 If the zone or discharge air sensor is unreliable, the damper is commanded to minimum position during Occupied and Standby modes and to 0% during Unoccupied mode. If the Outside air temperature is above the Economizer Switchover parameter, the economizer status is Off. If either the outside air or zone sensors become unreliable, economizer status is Off. Airflow Interlock An airflow switch is incorporated in the application. Airflow must be proven to operate the heating, cooling, and damper outputs. If airflow is lost for longer than the Fan Alarm Delay parameter; the heating, cooling, and damper commands go to 0%. If integration is used, the integrated value is zeroed and the fan status comes back on, the controller commands the outputs with a proportional-only command and then starts to add integration again. A fan alarm indication is given if the Fan Alarm Delay parameter expires and the fan command and airflow switch are in different states. Heating and Cooling Lockout When the outside air temperature exceeds the lockout setpoint, heating lockout status is On, indicating heat is unavailable. If the outside air temperature is below the cooling setpoint, cooling lockout status is On, indicating cooling is unavailable. Heating and cooling failsoft commands operate if the zone sensor becomes unreliable. Table 3 shows the status of the failsoft and the temperature conditions where it occurs. During cooling failsoft, you can specify the compressor output command between 0% and 100%. Table 3: Zone Sensor Unreliable Failsoft Lockout Status Outside Air Temperature (OAT) vs. Lockout temperature Lockout status Condition OAT > Heating Lockout On Heating Failsoft OAT < Heating Lockout* Off Heating Failsoft OAT > Cooling Lockout* Off Cooling Failsoft OAT < Cooling Lockout On Cooling Failsoft * Indicates a two-degree (C and F) differential, heating 2 and cooling +2.

23 23 Heat Pumps Applications Unitary heat pump equipment consists of factory-matched air conditioning systems that are shipped as complete, preassembled units and include internal wiring, controls, and piping. The heat pump acts as a heat engine in reverse. This means it requires work input to remove heat from a low temperature source and deliver it to a higher temperature sink. The heat pump achieves this by using refrigerant circulated within a compact closed-circuit coil to absorb and transfer heat from one area to another. The difference between a heat pump and a common air conditioner is the heat pump s ability to reverse the roles of the evaporator and condenser coils. The process begins with the evaporator coil absorbing heat from the air around it. The compressor then pumps refrigerant to the condenser where the heat is rejected to the surrounding air. During the cooling season, the unit reverses the evaporator and condenser coils, thus absorbing heat from inside the building and discharging it outside. The heat pump uses a single source of energy to fulfill a dual function of heating and cooling, so a single piece of equipment achieves year-round comfort. A reversing valve or valves, located in the refrigerant circuit, accomplishes the system changeover from Cooling to Heating mode. The heat pump application includes an economizer option to take advantage of outside air as a source of free cooling. The two basic types of unitary heat pumps in general use are the air to air and water to air heat pump. The air to air heat pump uses an air to refrigerant heat exchanger that extracts heat from outside air when heating indoor air, and rejects heat to outside air when cooling indoor air. Motor-driven or manually operated dampers can reciprocate the air circuit to obtain either heated or cooled air for the conditioned space. The water to air heat pump relies on water as the heat source and sink and uses air to transmit heat to or from the conditioned space. Typically, the water supply is a recirculating closed loop, but it could also be a well, lake, or stream. A refrigerant-to-water heat exchanger is used as a refrigerant heat source when heating indoor air and as a refrigerant heat sink when cooling indoor air. In both applications, specify whether mechanical cooling is prevented from operating based on the outside air temperature.

24 24 Pump Lead/Lag The use of electric-resistive elements as a supplemental heat source is optional. This is typical if heating needs exceed the capacity obtainable from equipment selected for the cooling load. The heaters only energize after all heat pump compressors are fully loaded. A user-defined delay takes effect following the transition to Standby or Occupied modes to prevent the supplemental heat from operating immediately after startup. This allows the heat pump compressors time to respond to a call for heat. An optional outside air sensor prevents heater elements from energizing during mild weather conditions when they are not needed. You can define a flow switch to prevent the heat pump from operating unless airflow is proven. In addition, immediate shutdown of compressors and supplemental heat results if loss of airflow occurs during normal operation. Control System Fault Tolerance Heating and cooling failsoft commands can operate the heat pump compressor if the zone sensor becomes unreliable. The command to the supplemental heat goes to 0% if the zone temperature sensor becomes unreliable. All other failsoft conditions are described in the sequence of operation. Applications A hot water or chilled water circulating system ordinarily uses two circulating pumps. They are used as the lead or main operating pump and the standby or backup pump. When the lead pump is enabled, it operates continuously. The status of the pumps can be monitored in two ways: a common flow switch for both or a separate flow switch for each pump. If the lead pump fails, it triggers an alarm and the lag pump starts. You have the option to turn off the output to the lead pump when the lead pump fails. The lead pump resumes operation when the alarm reset is triggered.

25 25 Questions Common to All Applications A common set of questions appears in each of the UNT application question/answer paths. A brief description of the results follows the question. The remainder of this topic provides related information on several of the questions in the common portion of the question/answer paths. Occupied Mode During Occupied mode, the controller sequences the heating/economizer/cooling outputs based on the occupied setpoints. During Unoccupied mode, the controller sequences the heating/economizer/cooling outputs based on the unoccupied setpoints. Standby Mode The Standby mode is an unoccupied strategy and does not have any effect when the controller is in the Occupied mode. When Standby is on, the controller sequences the heating/economizer/cooling based on the standby setpoints. Shutdown Mode All configurations have a Shutdown command as an option. When shutdown is enabled, the fan and cooling devices are commanded off, and the heating is commanded to the shutdown position specified by the user. At the same time, the integration timers are set to zero so no controller windup occurs while the system is off. The user-adjustable shutdown position for heating is available with HVAC PRO software Release 7.00 and later on Unit Vent applications only. All other UNT Configurations All configurations have a Shutdown command as an option. When shutdown is enabled, all fans, heating, and cooling devices are commanded to off (0% command). At the same time, the integration timers are set to zero so no controller windup occurs while the system is off. When the Shutdown command is issued to a normally open valve, the controller either sends 10 VDC (for an analog output) or energizes the triac providing 24 VAC (for binary outputs [BOs]) to drive the valve to its 0% flow position. When the Shutdown command is issued to a normally closed valve, the controller either sends 0 VDC (for analog output [AO]) or de-energizes the triac providing 0 VDC (for binary outputs) to drive the valve to its 0% flow position.

26 26 If your application requires the normally open valve to fail open on shutdown, there are two ways you can accomplish this: Add a relay to remove the 10 VDC or 24 VAC signal when shutdown is enabled. If you have a supervisory system, you can write logic to command the output to On (100% command). This causes the controller to send either 0 VDC (for an analog output) or de-energize the triac (for binary outputs), which drives the valve to its 100% flow position. All configurations have a Shutdown command as an option. When shutdown is enabled, all outputs to fans, heating, and cooling are turned off and integration timers are set to 0, so no windup occurs when the system is put back into control. Temporary Occupied Mode Temporary Occupied mode allows you to set the controller to Occupied mode for a user-defined time period and then return to Unoccupied mode. During Temporary Occupied mode, the controller maintains occupied temperature setpoints. For UNT applications, you may need to monitor the status of the temporary occupancy status data point to turn on the central system or maintain records for tenant billing. When you enable the Temporary Occupied mode, a time-out setpoint called occupied override time and a temporary occupancy status point are added to the parameter table. Once you start Temporary Occupied mode, it remains in effect until the override time runs out; it cannot be canceled. Boost Mode If you have not configured Temporary Occupied mode in your application, you may enable Boost mode. Boost mode allows an occupant to quickly change the controller s operating mode to full heating or cooling within an area. A popular application for Boost mode is a conference room where the number of people entering the room changes quickly, causing major load variations in the space. The controller must be in Occupied mode for Boost mode to work. While in Boost mode, the controller provides either 100% heating if the zone temperature is below the zone heating setpoint, or 100% cooling if the zone temperature is above the zone cooling setpoint, for a user defined period. If the temperature is in the deadband, pushing Boost has no effect. Boost mode is discontinued if the temperature moves into the deadband area (between heating and cooling setpoints).

27 27 When you enable Boost mode, time-out setpoints called Boost Override Time and Binary Data (BD) Status Point are added to the parameter table. To use the Boost mode, go to the parameters list box and specify the length of time that you want Boost mode to be active (in minutes) in the Boost Override Time field. The timer starts when you release the zone sensor momentary button and cannot be canceled. Diagnostics Unit Vent, Rooftop, Heat Pump, and Fan Coil UNT applications include the capability for diagnostics. The answer to the question asking the user to add diagnostics to the application defaults to Yes. Controllers Configured to Function as Point Multiplexers You can configure a controller to function as a point multiplexer module. This allows you to use all inputs and outputs for independent monitoring and control through the Metasys, N30/N31, or Companion/Facilitator systems. Note: The logic added when these questions are answered applies only to any sideloops that are defined later. It does not affect user-defined points that are not part of a sideloop. The remainder of this topic provides related information on the questions in the question/answer path. Occupied Mode During Occupied mode, the controller sequences the heating/economizer/cooling outputs based on the occupied setpoints. During Unoccupied mode, the controller sequences the heating/economizer/cooling outputs based on the unoccupied setpoints. Shutdown Mode All configurations have a shutdown command as an option. When shutdown is enabled, all outputs to fans, heating, and cooling are turned off and integration timers are set to 0, so no windup occurs when the system is put back in control.

28 28 Power Fail Restart Logic This mode allows you to disable all BOs of the controller that are in sideloops whenever the device first powers up; however, this does not apply to Binary Outputs associated with sideloops defined as Condition Single BOs or BOs mapped to a supervisory controller. You may stage the restart timers per floor or per area. This is useful when multiple controllers are used in a building, and you want to stagger the times when each controller energizes its outputs. A restart status variable indicates On for the duration of the delay. Point Multiplexer Input/Output Points The hardware inputs and outputs are all set to unused unless defined for occupied or shutdown mode during the Question and Answer session. To rename a point, follow the normal hardware definition steps to match the input or output type definition to the hardware being monitored or controlled. You can define any sideloops needed in the controller.

29 29 Procedure Overview Table 4: Using To Do This Create a Fan Coil Application Create a Unit Ventilator Application Create a Rooftop Unit Application Create a Telecommunications Hut Application Create a Heat Pump Application Create a Pump Lead/Lag Application Complete the Common Section of UNT Application Question/Answer Paths Configure a Controller as a Point Multiplexer Module Follow These Steps: On the File menu, click New. Select Application Group > Terminal Unit Applications. Select Application > Fan Coil. Answer the questions as they are presented. On the File menu, click New. Select Application Group > Terminal Unit Applications. Select Application > Unit Vent. Answer the questions as they are presented. On the File menu, click New. Select Application Group > Rooftop Applications. Select Application > Packaged Rooftop. Answer the questions as they are presented. On the File menu, click New. Select Application Type > Telecommunications Hut/POP Application. Select Compressor Lead/Lag Application or Compressor Stage Swapping Application. On the File menu, click New. Select Application Group > Terminal Unit Applications. Select Application > Heat Pump. Answer the questions as they are presented. On the File menu, click New. Select Application Group > Central Plant Applications. Select Application > Pump Lead/Lag Control. Answer the questions as they are presented. Answer the questions as they are presented. On the File menu, click New. Select Application Group > Generic I/O. Select Application > Point Multiplexer. Answer the questions as they are presented.

30 30 Detailed Procedures Creating a Fan Coil Application To create a fan coil application: 1. On the File menu, click New. 2. Select Application Group > Terminal Unit Applications. 3. Select Application > Fan Coil. 4. Answer the questions as they are presented (Figure 14) using the information in the remainder of this procedure as a guide. Note: Once you have answered the specific fan coil questions, the question/answer path automatically goes to the questions common to all applications. See the Completing the Common Section of UNT Application Question/Answer Paths procedure for a description of that path. Select Heating Type: Two Pipe Common Htg/Clg Coil (Incr) Two Pipe Common Htg/Clg Coil (Prop) None Proportional Normally Open Valve Normally Closed Valve/Single Stage Select Cooling Type: Incremental None Proportional Normally Open Valve Normally Closed Valve/Single Stage Incremental Fan Cycled during Occupied and Standby Modes? No Yes To Questions Common To All Applications Fancqa Figure 14: Fan Coil Question/Answer Path

31 31 Table 5: Select Heating Type Select Heating Type Choose from the options in Table 5. Option Two Pipe The controller determines the current mode using a binary input. When the binary input Common Htg/Clg indicates that the fan coil is in Heating (Htg) mode (on = heating mode), the controller Coil (incr) modulates a floating/three-wire valve to control the zone temperature at the heating setpoint. When the binary input indicates the fan coil is in Cooling (Clg) mode (off = cooling mode), the controller modulates a valve to control the zone temperature at the cooling setpoint. The controller uses two binary outputs to position the control valve. The specified stroke time determines the timing of these binary outputs. To determine the required valve position, the controller uses the zone temperature and energizes the appropriate output for a percent of full stroke. As the required position drops below the current position, the controller energizes the appropriate output to close the valve. As the required position increases, the controller energizes the other output to open the valve. When the change from the current position to the calculated new position is within the controller s deadband, neither output is energized, leaving the valve in its current position. The controller uses overdrive logic to ensure the position of the valve. When the output reaches 99%, it is driven for 1.5 times the stroke time, causing the valve to reach its 100% position. If the controller determines that the valve remains at the 100% position for 20 minutes, it again drives the output for 1.5 times the stroke time to ensure the device is in the proper position. This can occur again after another 20 minutes elapse and the valve remains at the 100% position. When the output reaches 1%, it is driven for 1.5 times the stroke time, causing the valve to reach its 0% position. If the controller determines that the valve remains at the 0% position for 20 minutes, it again drives the output for 1.5 times the stroke time to ensure the device is in the proper position. This can occur once more after another 20 minutes elapse and the valve remains at the 0% position. If your actuator does not have equal stroke times in the open and close directions, see the end of Table 59 for the equation to determine the proper stroke time for the actuator. The controller provides separate heating and cooling setpoints with associated proportional bands for each mode. Integration is available for each mode. Two Pipe The controller determines the current mode using a binary input. When the binary input Common Htg/Clg indicates that the fan coil is in Heating mode (on = Heating mode), the controller Coil (prop) modulates a valve to control the zone temperature at the heating setpoint. When the binary input indicates the fan coil is in Cooling mode (off = Cooling mode), the controller modulates a valve to control the zone temperature at the cooling setpoint. None There is no point/parameter assignment or logic sequence for this selection Proportional The controller modulates a valve from 0-100% as the zone temperature goes through the heating proportional band. Normally Open The controller provides a binary output to control a normally open heating valve. When Valve the zone temperature drops below the heating setpoint through the proportional band, the controller de-energizes the binary output. The binary output energizes when the zone temperature rises above the heating setpoint (see Figure 15). The binary output is subject to minimum on, minimum off, and cycles-per-hour settings. Normally Closed The controller provides a binary output to control the normally closed heating valve or Valve/Single normally off electric heat. When the zone temperature drops below the heating setpoint Stage through the proportional band, the controller energizes the binary output. The binary output is de-energized when the zone temperature rises above the heating setpoint. The binary output is subject to minimum on, minimum off, and cycles-per-hour settings. Continued on next page...

32 32 Option (Cont.) Incremental The controller uses two binary outputs to position the control valve. The specified stroke time determines the timing of these binary outputs. To determine the required valve position, the controller uses the zone temperature and energizes the appropriate output for a percent of full stroke. As the zone temperature drops below the heating setpoint through the heating proportional band, the required position changes from 0 to 100%. As the required position drops below the current position, the controller energizes the appropriate output to close the valve. As the required position increases, the controller energizes the other output to open the valve. When the change from the current position to the calculated new position is within the controller s deadband, neither output is energized, leaving the valve in its current position. The controller uses overdrive logic to ensure the position of the valve. When the output reaches 99%, it is driven for 1.5 times the stroke time, causing the valve to reach its 100% position. If the controller determines that the valve remains at the 100% position for 20 minutes, it again drives the output for 1.5 times the stroke time to ensure the device is in the proper position. This can occur again after another 20 minutes elapse and the valve remains at the 0% position. If your actuator does not have equal stroke times in the open and close directions, see the end of Table 59 for the equation to determine the proper stroke time for the actuator. Zone Temperature Heating Setpoint Heating = Off Heating Proportional Band Heating = On untcmd2 Figure 15: Heating Control Diagram for Normally Open and Normally Closed Valves

33 33 Table 6: Select Cooling Type Select Cooling Type Choose from the options in Table 6. Option None Proportional Normally Open Valve Normally Closed Valve/Single Stage Incremental There is no point/parameter assignment or logic sequence for this selection The controller modulates a valve from 0-100% as the zone temperature goes through the cooling proportional band. If heating is also selected, the cooling setpoint is above the heating setpoint to prevent simultaneous operation of heating and cooling. The controller provides a binary output to control a normally open cooling valve. When the zone temperature rises above the cooling setpoint through the proportional band, the controller de-energizes the binary output. The binary output energizes when the zone temperature drops below the cooling setpoint. The binary output is subject to minimum on, minimum off, and cycles-per-hour settings. The controller provides a binary output to control the normally closed cooling valve or normally off cooling stage. When the zone temperature rises above the cooling setpoint through the proportional band, the controller energizes the binary output. The binary output de-energizes when the zone temperature drops below the cooling setpoint. The binary output is subject to minimum on, minimum off, and cycles-per-hour settings. The controller uses two binary outputs to position the control valve. The timing of these outputs is based on an operator-specified stroke time. The controller uses the zone temperature to determine the required position of the valve. Then the controller causes the appropriate output to energize for a percent of full stroke to achieve the required valve position. As the zone temperature rises above the cooling setpoint, the controller energizes the appropriate output to open the valve. As the zone temperature decreases, the controller energizes the other output to close the valve. When the temperature is within the deadband of the controller, neither output energizes, leaving the valve in its current position. The controller uses overdrive logic to ensure the position of the valve. When the output reaches 99%, it is driven for 1.5 times the stroke time, causing the valve to reach its 100% position. If the controller determines that the valve remains at the 100% position for 20 minutes, it again drives the output for 1.5 times the stroke time to ensure the device is in the proper position. This can occur once more after another 20 minutes elapse and the valve remains at the 0% position. If your actuator does not have equal stroke times in the open and close directions, see the end of Table 59 for the equation to determine the proper stroke time for the actuator. Zone Temperature Cooling = On Cooling Setpoint Cooling Proportional Band Cooling = Off untcmd Figure 16: Cooling Control Diagram for Normally Open and Normally Closed Valve