Installation and Maintenance IM-709 Group: Applied Systems Part Number: IM709 Date: January 2002 Self-contained Air Conditioning System Type SWT C Vintage Sizes 18 thru 40 MEA 368-93-E 2002 McQuay International
Table of Contents Introduction............................... 3 General Description.................................... 3 Inspection............................................ 3 Installation................................ 4 Handling............................................. 4 Vibration Isolators...................................... 4 Location/Service Access................................. 4 Removal of Shipping Restraints and Construction Filter........ 4 Disassembly of Sections................................. 5 Field Mounting of Sensors............................... 6 Units with fan section shipped separate (code 21=*M)...... 6 Units ordered for modular construction (code 32=1)........ 6 Refrigerant Piping.......................... 7 Pressure Relief Valves.................................. 7 Water Connections......................... 8 General.............................................. 8 Condenser Piping 8 Condensate Drain Connection........................... 10 Duct Connections......................... 11 Supply Air........................................... 11 Return Air........................................... 12 Physical Data............................. 13 Dimensional Data......................... 15 Unit Weights............................. 18 Field Wiring.............................. 19 General............................................. 19 Unit Disconnect....................................... 19 Return Air and Outside Air Sensor......................... 19 Supply Power Wiring................................... 20 Lug Sizes For Single Disconnect or Power Block............. 20 Control Center............................ 21 Electrical Legend......................... 22 Typical Wiring Schematics.................. 23 Figure 18. Power Schematic............................. 23 Figure 19. Input Schematic, Discharge Air Control (DAC)....... 24 Figure 20. Input Schematic, Zone or Space Comfort (SCC...... 25 Figure 21. Output Schematic, Actuator Control............... 26 Figure 22. Output Schematic, Auxiliary Fan Start/Stop Control... 27 Figure 23 Output Schematic, Actuator Control............... 28 Figure 24. Output Schematic, Compressor Control (4 Compressors /4, 5 or 6 Stage)................. 29 Standard Controls......................... 30 High Pressure Switches................................ 30 Low Pressure Switches................................. 30 Compressor Motor Protector............................. 30 Proof of Airflow Switch.................................. 30 Frost Protection Switches............................... 30 Clogged Filter Switch................................... 30 Unit Options.............................. 31 Duct High Limit........................................ 31 Phase Fail/Under Voltage Protection....................... 31 Duct Static Pressure Sensor............................. 31 Building Static Pressure Sensor.......................... 31 Building pressurization applications........................ 32 Freezestat........................................... 32 Condenser Water Flow Switch........................... 32 Water Side Economizer................................. 32 Condenser Water, Head Pressure Control.................. 32 Variable Inlet Vanes.................................... 33 Variable Frequency Drive............................... 33 Disconnect Switch..................................... 33 Dual Power Supply..................................... 33 Electric Heat......................................... 33 Hot Water Control..................................... 33 System Check, Test and Start............... 34 General............................................. 34 Pre Start-up.......................................... 34 Start-up............................................. 34 General......................................... 34 Fan start-up...................................... 35 Compressor start-up................................ 35 Economizer start-up................................ 35 Hot water start-up................................. 35 Expansion valve superheat adjustment................. 35 Refrigerant Charge................................ 36 Variable air volume (VAV) start-up.................... 37 Rpm changes.................................... 37 Drive sheave alignment and belt tension............... 37 Maintaining control parameter records................. 37 System Maintenance....................... 38 Preventative Maintenance............................... 38 Motor Bearings....................................... 38 Replacement Parts........................ 39 Service and Warranty Procedure............. 40 In Warranty Return Material Procedure..................... 40 Replacement Parts.................................... 40 Product Warranty..................................... 40 System Check, Test and Start Form.......... 41 Copyright 2002 McQuay International. All rights reserved throughout the world. 2 IM709
Introduction General Description Models SWTO18C through 040C are factory assembled, refrigerant charged and tested, water cooled packaged air conditioning units designed for ducted applications. Each unit is comprised of three distinct sections: Main cooling/heating Filter/waterside economizer Fan section The unit is designed for easy disassembly for access to mechanical rooms, freight elevators, etc. The disassembly of the sections does not require the breaking of refrigeration lines. When a unit is knocked down the maximum section width including fastener heads is less than 341/2 inches. Once in the mechanical room the unit is easily reassembled. Each unit contains multiple scroll compressors, water cooled condensers, multi-circuit evaporator, thermostatic expansion valves, interconnecting refrigerant piping, forward curved centrifugal fan, belt drive, fan motor, 4 pleated filters and all necessary operating and safety controls. All rigging, installation, power and control wiring external to the unit, and condenser water and condensate piping are the responsibility of the installer. The MicroTech II self-contained unit controller is standard equipment on C vintage units. For a detailed description of the MicroTech components, input/output configurations, field wiring options and requirements, and service procedures, refer to Bulletin No. IM 710, MicroTech II Self-contained Unit Controller For a description of operation and information on using and programming the MicroTech II unit controller, refer to the appropriate operation manual (see Table 1). Table 1: Self-contained unit operation manual literature SELF CONTAINED UNIT CONTROL CONFIGURATION Inspection OPERATION MANUAL BULLETIN NUMBER Discharge Air Control (VAV or CAV) OM 711 Space Comfort Control (CAV-ZTC) OM 712 When the equipment is received, check all items carefully checked against the bill of lading to verify a complete shipment. The shipping receipt should not be signed until all items have been accounted for. All units should be carefully inspected for damage upon arrival. All shipping damage should be reported to the carrier and a claim filed. The unit serial plate should be checked before unloading the unit to be sure that it agrees with the power supply available Nomenclature SWT-040-C Self-contained Water cooled Top discharge Vintage Nominal tons IM709 3
Installation Note: Handling Installation and maintenance must be performed only by qualified personnel who are familiar with local codes and regulations, trained and experienced with this type of equipment. CAUTION Sharp edges and coil surfaces are a potential injury hazard. Avoid contact with them. Units may be shipped in one or two sections. When the unit is shipped in two sections the fan section is separate from the base sections. Units are shipped with a protective covering which should remain in place while the unit is being moved to its final location. Note: Check for concealed damage as soon as possible. Never allow any part of the unit to fall during unloading or moving as this may result in serious damage. When the fan section ships separate, lifting lugs are provided for rigging and handling. The lugs are mounted on the fan section. If the fan section ships attached to the base sections, lifting lugs are not provided. The unit base sections will accept lifting rods through channels on the base rail. If units are lifted by crane, protection against chaffing damage by slings or cable must be provided and spreader bars must be used across the top of the cabinet to prevent structural damage to the frame. For units provided with more than (8) isolator pads, evenly space the additional pads under the front and rear base channels. Location/Service Access For good installation, service and maintenance access the following recommended clearances should be followed. Clearance is required to allow room for side filter access, mechanical cleaning of the condenser tubes and economizer coil, access to expansion valves and other control components and to allow for possible fan shaft or compressor removal. Unit front - 42" Unit rear - 24" Unit left side- 36" Unit right side - 36" Figure 1: Recommended Service and Maintenance Clearance Airflow Evaporator Coil 24" CAUTION Do not attempt to install dollies in the center of the unit. 24" or 36" Compressors 1 3 4 2 36" CAUTION AFD Units must not be moved in an upended position. 42" Floor surfaces must be protected when equipment is moved across finished flooring. Plywood sheeting may be used to protect surfaces and distribute weight loading. Vibration Isolators All units are provided with 1 neoprene isolation pads, shipped separately. Pads are to be installed beneath the unit and located at each corner and the center of each base channel. Removal of Shipping Restraints and Construction Filter Mechanical restraints are used to secure the spring mounted fan during shipment. Restraints and shipping blocks must be removed after unit has been set in its final location. 4 IM709
Disassembly of Sections If units are ordered for modular construction, they may be easily disassembled into three sections. The figures below illustrate the main cooling/heating, filter/waterside economizer, and fan sections. The thick lines in the figures show where the sections are disassembled. The section are secured by connection plates and screws. The following information describes the location of the connecting points. Fan section base sections disassembly The fan section sits on the base sections and is secured with four steel plates. Each plate has two screws in the base sections and two screws in the fan section. Two of the plates are shown in Figure 3. The connection plates are also the rigging plates for the fan section only. They must not be used for rigging the entire unit. Main cooling/heating filter/waterside economizer sections disassembly The following information is for units ordered for modular construction (code 32=1). Note: The disassembly of units not ordered for modular construction (code 32=Y) will require field modification. Units not ordered for modular construction do not have victaulic couplings on the water pipes and the various control sensors are mounted in the unit. Two steel plates the height of the sections connect the main cooling/heating and the filter/waterside economizer sections. The plates are secured with multiple screws on the right and left side of the base sections. The connection plate and screws are illustrated in Sect A-A. The filter/waterside economizer section overlaps the main cooling/heating sections along the bottom and top adjoining rails. Multiple screws connect the two sections along these bottom and top overlaps. Victaulic couplings connect the water pipes between the filter/waterside and main cooling/heating sections. Each victaulic coupling is secured with two bolts.the condensate drain pipe between the two sections is connected by a flexible PVC tube with pipe clamps. Figure 2 Figure 3 Fan Outlets Fan Section Connection Plates (2) FILTER SECTION ECONOMIZER A A EVAPORATOR HEATER ELECTRICAL PANEL Main Cooling/ Heating Section ASD (Optional) Filter/Waterside Economizer Section Condenser Compressor (1) Unit sizes 018, 023 and 028 have a single fan. (2) Connection Plates are also the Rigging Plates for the Fan Section only. IM709 5
Field Mounting of Sensors Units with fan section shipped separate (code 21=*M) The following items require field connection or mounting when the fan section is shipped separate: Fan Motor(s) power harness(es) need to be connected to the OL10 overload(s) on the control board. The power harness is located in the fan section with one end connected to the fan motor. The other end of the power harness needs to be connected to the control panel. Three penetration hole are provide to the control panel. The holes are pre-punched in the upper right hand side of the control panel when facing the control panel. Select one of the holes and cut out the insulation. Mount the power harness conduit fitting in the hole. Connect the three fan power wires to the leaving side of the OL1 0 overload. Supply Air Sensor The sensor will be shipped loose in the main cooling/heating section on the right side when facing the control panel. The sensor will be labeled SAT. Move the SAT sensor into the fan section. The mounting location is on the right side of the fan section when facing the unit front. The mounting hole is labeled SAT on a plate at the bottom of the fan. Duct High Limit Tube The tube is shipped loose in the main cooling/heating section on the left side when facing the unit front. The tube is labeled DHL. The duct high limit tube should be mounted on the left side of the fan section regardless of front or back discharge. The mounting location is labeled DHL TUBE on the flex duct metal. Place tube and holder through flex duct assembly and screw locking nut on the inside of the fan. VIV (optional) actuator and feedback potentiometer control wire need to be connected. The VIV control wiring penetrates the control board in the upper left corner when facing the front of the unit. The connectors from the control board are shipped loose in the main cooling/heating section. The connectors from the VIV actuator are shipped loose in the fan section. The control wire coming from the actuator motor has a socket connector which matches the prong connector from the control panel. The control wire for the feedback potentiometer has a prong connector which matches the socket connector from the control panel. This logic of prong and socket connections prevents cross wiring of the actuator motor and feedback potentiometer control wiring. Units ordered for modular construction (code 32=1) Right side of unit The following items require field connection or mounting in the filter/waterside economizer section. Each item is shipped loose in the main cooling/ heating section. The four items are located on the right side of the section when facing the front of the unit. A hole is provided leaving the main cooling/heating section entering the filter/waterside economizer section. Each item needs to be threaded through this hole into the filter/waterside economizer section. The mounting location of the four items is the space after the filters and before the coils. The following provide mounting hole locations for each item: Mixed Air Sensor - Identify the sensor labeled MAT. Mount the sensor in the 2nd hole from the top labeled MAT. Plastic Tube for Air Flow and Clogged Filter Switch - The tube for pressure sensing on the Proof of Air Flow Switch (PC7) and the Clogged Filter Switch (PC5) is labeled PC5/PC7. Freezstat If the optional Freezstat is ordered its control wiring must be connected. Plug the control wiring into the freezstat mounted on the top hole. Left or right side of unit The following items are located on the same side of the unit as the water piping connections. The water piping connections may be ordered right or left hand. Each of these items requires field mounting or connections. Mount the EWT and LWT temperature sensors in the filter/waterside economizer section. The sensors are shipped loose on the bottom of main cooling/heating section on the side of the water connections. Identify the sensor labeled EWT and mount to the holder at the bottom the entering water tube. The entering water tube is the bottom tube and is labeled at the point it penetrates the unit. Identify the sensor labeled LWT and mount to the holder at the bottom of the leaving water tube. The leaving water tube is above the entering water tube and is labeled at the point it penetrates the unit. Connect the control wiring for the valve(s) actuator and feedback potentiometer which control the water flow through the waterside economizer (optional) and condenser. The wire connectors from the control board are shipped loose in the base of the main cooling/heating section. The wire connectors from the valve actuator(s) are shipped loose in the base of filter/waterside economizer section. The control wire coming from the actuator motor has a socket connector which matches the prong connector from the control panel. If there is more than one actuator motor, the wire number on the socket connector must match the wire number on the prong connector. If the wire numbers are not matched, the valves will not be controlled properly. The control wire for the feedback potentiometer has a prong connector which matches the socket connector from the control panel. This logic of prong and socket connections prevents cross wiring of the actuator motor and feedback potentiometer control wiring. 6 IM709
Refrigerant Piping Pressure Relief Valves All units have individual condensers per refrigerant circuit and each condenser is provided with a spring loaded relief valve. The valve is set to open when refrigerant pressure reaches 400 psig. The relief valve will accommodate a 1/2" flare connection for applications where it is necessary to connect vent piping and run it outside the building. CAUTION When refrigerant is vented to the outside of the building, install the vent piping as recommended in ASHRAE Standard 15-1992. IM709 7
Water Connections General Due to the variety of piping practices, follow the recommendations of local authorities. They can supply the installer with the proper building and safety codes required for codecompliant proper installation. Basically, the piping should be installed with a minimum number of bends and elevation changes for best performance. Piping should contain: 1. Vibration eliminators to reduce vibration and noise transmission to the building. 2. Shutoff valves to isolate the unit from the piping system during unit servicing. 3. Manual or automatic air vent valves at the high points of the system. 4. Some means of maintaining adequate system water pressure (e.g., expansion tank or regulating valve). 5. Temperature and pressure indicators located at the unit to aid in servicing. 6. A strainer or some means of removing foreign matter from the water before it enters the pump. It should be placed far enough upstream to prevent cavitation at the pump inlet (consult pump manufacturer for recommendations). The use of a strainer will help prolong pump life and help maintain system performance. 7. Size piping to minimize system pressure drop. Condenser Piping 1. Units may be specified with water and condensate connections on either end of the unit. 2. All units have an individual condenser per refrigerant circuit. All condensers are factory piped for a common condenser supply and a common condenser return connection. 3. Field piping connections are made to factory provided piping located as indicated on the unit submittal drawings. Units with factory provided water side economizer coil have the piping connections run to the outside of the unit cabinet. Connections are located behind a factory mounted shipping cover. Connections are located behind a factory mounted cover plate. All connections are copper, sweat connections as indicated on unit dimensional drawings. 4. Supply and return water connections must be made at the proper locations as indicated by the dimensional drawings. Supply (water in) connection is always the lower connection. 5. Units with factory mounted water side economizer should not require head pressure control. The economizer will typically elevate the water temperature by 5 to 10 F before entering the condenser, allowing suitable condenser water temperatures whenever the tower supply temperature is 50 F or higher. Without head pressure control, mechanical cooling is locked out below 55 F EWT. 6. Head pressure control must be provided if no economizer is used and if entering condenser water temperatures will go below 55 F. Fan cycling and/or modulating discharge dampers on the cooling tower are often used, or a 3-way bypass around the tower. Cooling tower control to maintain the temperature at >55 F is generally more cost effective if multiple units are in the loop. If valves are installed on the individual SWP units, a single water regulating valve controlled by circuit #1 head pressure should be used. The Lead/Lag option must equal NO. When Lead/Lag equals NO circuit #1 is always first on and last off. The refrigerant pressure line from the valve should be connected to a gauge port on any liquid line service valve located in compressor #1 refrigerant circuit. Compressor #1 is located at the far left of the cabinet. Figure 4. Condenser Regulating Valve (refrigerant pressure controlled) If the water regulating valve is placed in series with the unit condensers, it should be installed in the water line leaving the condenser and should shutdown to prevent water from siphoning out of the condensers. For systems where a constant pumping head is required, the water regulating valve may be installed in a bypass line around the condensers. It must then open on falling discharge pressure. These typical systems, depending on the specific application, must maintain a constant condensing pressure regardless of temperature conditions and must assure adequate head pressure for proper thermostatic expansion valve operation. A minimum head pressure of 160 psig (86 F condensing temperature) is recommended. 7. Condenser tube velocities must not exceed 10 feet per second. Flow and velocity will be satisfactory if water volumes do not exceed those shown in Table No. 4. 8 IM709
Figure 5. Condenser water pressure drop SWT018C-028C (60) 20 Figure 7. Waterside economizer pressure drop SWT018C-040C (210) 70 (180) 60 (45) 15 25 hp 30 hp (150) 50 (120) 40 (90) 30 Water Pressure Drop (kpa) ft. w.g. (30) 10 (27) 9 (24) 8 (21) 7 (18) 6 (15) 5 (12) 4 10 hp 15 hp 20 hp Water Pressure Drop (kpa) ft. w.g. (60) 20 (45) 15 (30) 10 (27) 9 (24) 8 (21) 7 (18) 6 (15) 5 018-028 035-040 (12) 4 (9) 3 (9) 3 (6) 2 20 (1.2) 30 (1.9) 40 (2.5) 50 (3.2) 60 (3.8) 70 80 90 100 (4.4) (5.1) (5.7) (6.3) Water Flow Rate - gpm (L/s) Note: HP = total unit compressor horsepower 150 (9.5) (6) 2 20 (1.2) 30 (1.9) 40 (2.5) 50 60 70 80 90 100 (3.2) (3.8) (4.4) (5.1)(5.7) (6.3) 150 (9.5) 200 (12.6) Water Flow Rate - gpm (L/s) Note: 1. Includes coil, control valve and interconnecting piping. 2. Add this )P to condenser )P to obtain unit )P for pump selection. Figure 6. Condenser water pressure drop SWT035C-040C (60) 20 Figure 8. Hot water coil pressure drop SWT035C-040C (45) 15 30 hp 35 hp 40 hp (210) 70 (180) 60 (150) 50 (120) 40 023 035 040 028 Water Pressure Drop (kpa) ft. w.g. (30) 10 (27) 9 (24) 8 (21) 7 (18) 6 (15) 5 20 hp 25 hp Water Pressure Drop (kpa) ft. w.g. (90) 30 (60) 20 (30) 10 (24) 8 (18) 6 (15) 5 (12) 4 018 (12) 4 (9) 3 20 (1.2) 30 (1.9) 40 (2.5) 50 (3.2) 60 (3.8) 80 (5.1) Water Flow Rate - gpm (L/s) 100 (6.3) Note: Includes coil, control valve and interconnecting piping. 150 (9.5) (9) 3 40 (2.5) 50 (3.2) 60 (3.8) 70 (4.4) 80 (5.1) 90 100 (5.7) (6.3) Water Flow Rate - gpm (L/s) Note: HP = total unit compressor horsepower 150 (9.5) 200 (12.6) IM709 9
Figure 9. Water regulating valve pressure drop Head pressure control (120) 40 (105) 35 (90) 30 (75) 25 (60) 20 (45) 15 Condensate Drain Connection The condensate drain connection is 11/8" O.D.S. copper and is located on the same end of the unit as the condenser water connections. The drain is internally trapped at the factory requiring no external trap. The condensate line should be pitched away from the unit with a minimum slope of 1/8" per foot. Drain pans and the drain trap should be kept clean by periodic cleaning. A cleanout is provided as standard in the trap to aid in cleaning. Water Pressure Drop (kpa) ft. w.g. (30) 10 (27) 9 (24) 8 (21) 7 (18) 6 (15) 5 (12) 4 (9) 3 018-028 035-040 (6) 2 (3) 1 20 30 40 50 60 70 80 90 100 (1.2) (1.9) (2.5) (3.2) (3.8) (4.4) (5.1) (5.7) (6.3) Water Flow Rate - gpm (L/s) Note: Includes coil, control valve and interconnecting piping. 150 (9.5) 200 (12.6) 10 IM709
Duct Connections Supply Air For connection of supply ductwork directly to the unit, a duct collar must first be mounted at the fan outlet, avoiding the mounting screws located around the perimeter of the fan discharge opening. Fan discharge opening sizes are indicated on the unit dimensional drawings. When connecting ductwork to the unit, use a canvas type connecting collar. To maintain specified fan performance, two-fan units should incorporate a properly designed "pants" duct connection (refer to Figure 10). Units are available in two fan configurations as shown in Figure 11. Duct take-offs which go opposite to the direction of fan rotation will result in an associated system effect loss and reduced fan performance. Figure 10. Two-fan unit top detail Figure 11. Discharge duct configuration IM709 11
Return Air Air return to the unit can be arranged in different ways. 1. Ducted return Return ductwork may be attached to the 2" flange around the perimeter of unit's return air opening (refer to Figure 12). Use a canvas type duct connecting collar. All ductwork connected to the unit should be of adequate size and construction for the application. A canvas type connector is also recommended where the duct penetrates the machine room wall(s). This will help prevent vibration generated by air movement in the duct from being transmitted out to the occupied spaces. Figure 12. Return duct connections Note: Do not obstruct unit access panel located below the return opening. Note: For units with ducted return, connect the open port on the clogged filter switch (PC5) to the return air duct. 2. Free return The mechanical equipment room may be used as a return plenum with no hard connection at the unit. Note: Some building codes do not allow the use of the mechanical room as a return plenum. Check applicable local codes for each installation. 12 IM709
Physical Data Table 2. SWT018C-040C English units DATA SWT MODEL SIZE 018C 023C 028C 035C 040C COMPRESSOR Quantity 2, 3, 4 3, 4 4 4 4 Size (see application chart, Table 4) EVAPORATOR COIL Face area (in2) 11.8 15.3 18.9 23.3 26 3 Rows 4, 6 4, 6 4, 6 4, 6 4, 6 FPI 12 12 12 12 12 PERFORMANCE Nominal tons 13.6 19.7 25.8 31.1 35.6 WATERSIDE ECONOMIZER COIL Face area (in2) 11.8 15.3 18.9 23.3 26.3 Rows 4 4 4 4 4 FPI 12 12 12 12 12 Max. working press. 400 400 400 400 400 HOT WATER HEATING COIL Face area (in2) 9.3 12.8 16.3 20.2 23.8 Rows 1 1 1 1 1 FPI 12 12 12 12 12 ELECTRIC HEAT kw 34 34 34 34 34 FILTERS (5) 20x20x4 (5) 20x20x4 (Qty) size (in) (4) 2Ox20x4 (4) 20x20x4 (4) 20x20x4 (5) 25x20x4 (5) 25x20x4 (4) 25x20x4 (4) 25x20x4 (4) 25x20x4 EVAPORATOR FAN Quantity 1 1 1 2 2 Size (in) 15 18 18 15-15 15-15 Minimum hp 5 7.5 10 10 15 Maximum hp 10 15 20 20 25 Min. Design cfm, CV 2950 3825 4725 5825 6575 Min. Design cfm, VAV 4720 6120 7560 9320 10520 Max. Design cfm 7080 9180 11340 13980 15780 CONDENSER Quantity 2, 3, 4 3, 4 4 4 4 W.S. working press. 400 400 400 400 400 Min entering temp. (F) 55 55 55 55 55 Table 2a. SWT018C-040C SI units DATA SWT MODEL SIZE 018C 023C 028C 035C 040C COMPRESSOR Quantity 2, 3, 4 3, 4 4 4 4 Size (see application chart, Table 4) EVAPORATOR COIL Face area (m2) 1.10 1.42 1.76 2.16 2.44 Rows 4, 6 4, 6 4, 6 4, 6 4, 6 FPI 12 12 12 12 12 PERFORMANCE Nominal tons 13.6 19.7 25.8 31.1 35.6 WATERSIDE ECONOMIZER COIL Face area (m2) 1.10 1.42 1.76 2.16 2.44 Rows 4 4 4 4 4 FPI 12 12 12 12 12 Max. working press. 400 400 400 400 400 HOT WATER HEATING COIL Face area (m2) 0.9 1.2 1.5 1.9 2.2 Rows 1 1 1 1 1 FPI 12 12 12 12 12 ELECTRIC HEAT kw 34 34 34 34 34 FILTERS (Qty) size (mm) (4) 508x508x102 (4) 508x508x102 (4) 508x508x102 (4) 508x508x102 (4) 508x508x102 (4) 508x508x102 (5) 508x508x102 (5) 508x508x102 (5) 508x508x102 (5) 508x508x102 EVAPORATOR FAN Quantity 1 1 1 2 2 Size (in) 15 18 18 15-15 15-15 Minimum hp 5 7.5 10 10 15 Maximum hp 10 15 20 20 25 Min. Design L/s, CV 310 852 1053 1298 1465 Min. Design L/s, VAV 2228 2889 3568 4399 4965 Max. Design L/s 3342 4333 5352 6599 7448 CONDENSER Quantity 2, 3, 4 3, 4 4 4 4 W.S. working press.(pa) 2.8 2.8 2.8 2.8 2.8 Min entering temp. (C) 13 13 13 13 13 IM709 13
Table 3. Compressor circuit charge COMPRESSOR (HP) *REFRIGERANT CHARGE PER CIRCUIT (R-22) OIL CHARGE PER CIRCUIT (OZ.) 6 9 Ibs. 53 10 14 lbs. 132 13 18 lbs. 128 * Charge quantities listed are averages. Actual charge quantity is dependent on individual unit evaporator coil circuiting. Actual charge quantities are stamped on each unit nameplate. Table 4. Compressor application chart SWT MODEL SIZE 018C 023C 028C 035C 040C COMPRESSOR HORSEPOWER CKT#1 CKT#2 CKT#3 CKT#4 MIN. GPM (L/s) MAX GPM (L/s) 6 6 - - 24 (1.5) 42 (2.7) 6 6 6-36 (2.3) 62 (4.0) 6 6 6 6 48 (3.0) 84 (5.3) 6 6 6-35 (2.2) 65 (4.1) 6 6 6 6 48 (3.0) 84 (5.3) 6 6 6 6 58 (3.7) 102 (6.4) 6 6 6 10 58 (3.7) 102 (6.4) 6 6 10 10 68 (4.3) 119 (7.5) 6 6 6 6 48 (3.0) 84 (5.3) 6 6 6 10 58 (3.7) 102 (6.4) 6 6 10 10 68 (4.3) 119 (7.5) 6 10 10 10 78 (4.9) 137 (8.7) 6 6 6 10 58 (3.7) 102 (6.4) 6 6 10 10 68 (4.3) 119 (7.5) 6 10 10 10 78 (4.9) 137 (8.7) 10 10 10 10 88 (5.6) 154 (9.7) 6 6 6 10 58 (3.7) 102 (6.4) 6 6 10 10 68 (4.3) 119 (7.5) 6 10 10 10 78 (4.9) 137 (8.7) 10 10 10 10 88 (5.6) 154 (9.7) 10 10 13 13 104 (6.5) 13 13 13 13 120 (7.6) 183 (11.5) 212 (13.4) 14 IM709
Dimensional Data Figure 13. Left Side Front (CW) Discharge Figure 14. Left Side Back (CCW) Discharge Note: (1) Select unit arrangement on the unit selection. (2) There are two victaulic connections for condenser water at module split. Table 5. BASIC UNIT 018C 023C 028C 035C 040C (1) (2) 52.00 52.00 52.00 52.00 52.00 A. DEPTH (1321mm) (1321mm) (1321mm) (1321mm) (1321mm) B. LENGTH (1) (2) 84.00 84.00 84.00 84.00 84.00 (2134mm) (2134mm) (2134mm) (2134mm) (2134mm) (1) (2) 112.75 112.75 112.75 112.75 112.75 C. HEIGHT (2864mm) (2864mm) (2864mm) (2864mm) (2864mm) D. FAN DISCHARGE E. FAN DISCHARGE 18.62 21.88 21.88 18.62 18.62 (473mm) (556mm) (556mm) (473mm) (473mm) 15.88 18.88 18.88 15.88 15.88 (403mm) (480mm) (480mm) (403mm) (403mm) BASIC UNIT 018C 023C 028C 035C 040C F. UNIT SIDE TO FAN G. RETURN DUCT HEIGHT H. RETURN DUCT LENGTH J. WATER OUT/IN (ODS) K. HOT WATER OUT/IN (ODS) 32.69 31.06 31.06 23.88 23.88 (830mm) (789mm) (789mm) (606mm) (606mm) 45.94 45.94 45.94 45.94 45.94 (1167mm) (1167mm) (1167mm) (1167mm) (1167mm) 80.00 80.00 80.00 80.00 80.00 (2032mm) (2032mm) (2032mm) (2032mm) (2032mm) 2 1/8 2 1/8 2 1/8 2 5/8 2 5/8 1 5/8 1 5/8 1 5/8 1 5/8 1 5/8 (1) Dimensions do not include handle, latch or fastener extensions. (2) For shipping dimensions the skid adds 4 to Depth, 8 to Length and 4 to Height. IM709 15
Figure 15. Unit Front Plan and Front Elevation Return Air Left side piping connections Right side piping connections (optional) Supply fan motor Unit Front Plan F D 15.0 (381) D F 6.46 (164) 34.0 (864) Fan Outlets E 78.5 (199.4) MicroTech II System Indicator Panel ASD (Optional) Connection Plate Power entry 7/8" (2.2) KO Electrical Access 72.0 (182.8) Mechanical Access B Front Elevation (For dimentions B, D, E and F see Table 5) 1.0 (25)Neoprene Isolation Pads shipped separately Notes: 1. Service connections determined when facing the front of the unit. Left hand standard, right hand optional. Please indicate on the unit submittal. 2. Unit sizes 018C, 023C and 028C have a single fan. 3. Unit sizes 018C, 023C and 028C have a single mechanical access panel in bottom front and bottom back. 16 IM709
Figure 16. Back Elevation and Left Side Notes: 6. Filters are removable from the rear of the unit or through a side filter access door, located on the piping connection side. 7. Length will be increased by approximately 3.5 (89mm), for piping connections when water economizer option is ordered. 8. Mechanical access panel(s) in the back of the unit start 2 (51mm) below return duct opening. Do not obstruct the access panel(s). 9. There are two access doors on 018C, 023C and 028C instead of three as shown. 10. All dimensions are given in inches with millimeters in parentheses. 11. All dimensions ± 0.25 (6.4mm). IM709 17
Unit Weights Table 6a. Unit and Component Weight English Units in lbs. Table 6b. Unit and Component Weight SI Units in kg. COMPONENT UNIT SIZE 018C 023C 028C 035C 040C MAIN COOLING/HEATING SECTION Main Base 946 946 946 1045 1045 4 Row DX Coil 206 238 278 333 354 6 Row DX Coil 250 294 347 417 450 Comp./Cond. Water (2) 6 hp 26 560 (3) 6 hp 35 705 705 (4) 6 hp 43 856 856 856 856 (3) 6, (1) 10 hp 57 987 987 987 987 (2) 6, (2) 10 hp 66 1105 1105 1105 1105 (1) 6, (3) l0 hp 74 1233 1233 1233 (4) 10 hp 95 1368 1368 (2) 10, (2) 13 hp 1511 (4) 13 hp 1654 Hot Water Coil, 1 Row, 12 fpi (2) 71 97 119 130 152 HW Coil Water Weight 16 20 23 28 32 Electric Heat -34 kw 20 20 20 20 20 Skid for Main 99 99 99 115 115 FILTER/WATERSIDE ECONOMIZER SECTION Base 368 368 428 428 Water Economizer Coil 4 Row (1) 266 298 340 393 410 Economizer Water Weight 51 65 75 94 111 FAN SECTION Fan & Frame 900 930 930 1120 1120 Skid for Fan Section 98 98 98 115 115 Supply Fan Motors 3 hp Open Dripproof 71 5 hp Open Dripproof 82 7 1/2 hp Open Dripproof 124 124 l0 hp Open Dripproof 144 144 144 144 l5 hp Open Dripproof 185 185 185 185 20 hp Open Dripproof 214 214 214 25 hp Open Dripproof 266 3 hp Totally Enclosed 72 5 hp Totally Enclosed 85 71/2 hp Totally Enclosed 140 140 10 hp Totally Enclosed 170 170 170 170 15 hp Totally Enclosed 235 235 235 235 20 hp Totally Enclosed 300 300 300 25 hp Totally Enclosed 330 (1) Water economizer weight includes valves and piping. (2) Hot water coil weight includes valve piping COMPONENT UNIT SIZE 018C 023C 028C 035C 040C MAIN COOLING/HEATING SECTION Main Base 429 429 429 474 474 4 Row DX Coil 94 108 126 151 161 6 Row DX Coil 113 133 157 189 204 Comp./Cond. Water (2) 6 hp 12 254 (3) 6 hp 16 320 320 (4) 6 hp 20 388 388 388 388 (3) 6, (1) 10 hp 26 448 448 448 448 (2) 6, (2) 10 hp 30 501 501 501 501 (1) 6, (3) l0 hp 34 559 559 559 (4) 10 hp 43 621 621 (2) 10, (2) 13 hp 680 (4) 13 hp 744 Hot Water Coil, 1 Row, 12 fpi (2) 32 44 54 59 69 HW Coil Water Weight 7 9 10 13 15 Electric Heat -34 kw 9 9 9 9 9 Skid for Main 45 45 45 52 52 FILTER/WATERSIDE ECONOMIZER SECTION Base 167 167 167 194 194 Water Economizer Coil 4 Row (1) 121 135 154 178 186 Economizer Water Weight 23 29 34 43 50 FAN SECTION Fan & Frame 408 422 422 508 508 Skid for Fan Section 44 44 44 52 52 Supply Fan Motors 3 hp Open Dripproof 32 5 hp Open Dripproof 37 7 1/2 hp Open Dripproof 56 56 l0 hp Open Dripproof 65 65 65 65 l5 hp Open Dripproof 84 84 84 84 20 hp Open Dripproof 97 97 97 25 hp Open Dripproof 121 3 hp Totally Enclosed 32 5 hp Totally Enclosed 39 71/2 hp Totally Enclosed 64 64 10 hp Totally Enclosed 77 77 77 77 15 hp Totally Enclosed 107 107 107 107 20 hp Totally Enclosed 136 136 136 25 hp Totally Enclosed 150 (1) Water economizer weight includes valves and piping. (2) Hot water coil weight includes valve piping 18 IM709
Field Wiring General Wiring must comply with all applicable codes and ordinances. The warranty does not cover equipment failures caused by or contributed to wiring not in accordance with specifications. An open fuse indicates a short, ground or overload. Before replacing a fuse or restarting a compressor or fan motor, the trouble must be found and corrected. Use copper wire for all power lead terminations. Contact factory for information concerning aluminum wire power lead terminations. A single power terminal block is provided as standard and wiring within the unit is done in accordance with the National Electric Code. All branch circuits within the control panel are individually fused. A single field supplied disconnect is required or a unit mounted nonfused disconnect can be ordered with the unit. Table 7. Compressor Motors A 7/8 knockout is located on the right-hand unit upright for locating unit power entry. 24V field connections are suitable for Class II wiring. Unit Disconnect Disconnecting means are addressed by Article 440 of the National Electric Code (NEC) which requires disconnecting means capable of disconnecting air conditioning and refrigerant equipment including motor-compressors, and controllers, from the circuit feeder." The disconnect switch should be selected and located within the NEC guidelines. Location requirements per NEC are that the disconnect be located in a readily accessible position within sight (50 feet) of the unit. A factory mounted nonfused disconnect is available. Table 7. Compressor Motors Return Air and Outside Air Sensors All units are provided with a return air sensor. The outside air sensor is optional and can be ordered with the unit. The return air sensor is connected to the input control board and is coiled up and placed in the control box of the unit for shipment. The return air sensor must be field installed in the return air stream for proper unit operation. The outside air sensor is shipped loose in a package and is located on the floor of the fan section. The mixed air temperature sensor is already installed at the inlet of the unit. The sensors must be mounted in areas that are exposed to representative temperature conditions. The sensor should be mounted at a position that has good air mixing and does not have stratification. The sensor can be mounted in the ductwork using a grommet, see Figure 17. Figure 17. Return/Outside Air Sensor Mounting Ductwork Sensor Grommet The return air sensor is connected to the unit s input board at location AI4, see IM710. The outside air sensor is field wired to terminal strip TB2. The sensor is to be connected at terminals 124 and 125. Compressor 208/60/3 230/60/3 400/50/3 460/60/3 575/60/3 HP RLA LRA RLA LRA RLA LRA RLA LRA RLA LRA 6 17.9 156.0 16.2 156.0 8.1 70.0 8.1 70.0 6.5 54.0 10 31.2 239.0 28.2 239.0 14.1 125.0 14.1 125.0 11.3 80.0 13 35.6 350.0 32.0 350.0 16.0 158.0 16.0 158.0 12.8 125.0 Table 8. Electric Heaters 208V/60HZ/3PH 230V/60HZ/3PH 400V/50HZ/3PH 460V/60HZ/3PH 575V/60HZ/3PH SWP UNIT SIZE kw MBH FLA kw MBH FLA kw MBH FLA kw MBH FLA kw MBH FLA 018-040 27.8 94 77.2 34 116 85.6 25.7 88 37.2 34 116 42.8 34 116 34.2 IM709 19
Table 9 Supply Fan Motor Data Horsepower 3 5 7.5 10 15 20 25 TYPE 208/60/3 230/60/3 400/50/3 a 460/60/3 575/60/3 FLA FLA FLA FLA FLA High Efficiency 9.9 9.0 4.5 4.5 3.4 Premium Efficiency 9.3 8.2 4.1 4.1 3.1 High Efficiency 14.8 14.0 7.0 7.0 5.3 Premium Efficiency 15.7 13.6 6.8 6.8 5.2 High Efficiency 22.3 21.6 10.8 10.8 8.2 Premium Efficiency 22.3 20.0 10.0 10.0 7.4 High Efficiency 29.7 28.0 14.0 14.0 11.0 Premium Efficiency 29.0 25.8 12.9 12.9 10.3 High Efficiency 44.4 40.6 20.3 20.3 16.2 Premium Efficiency 43.4 37.8 18.9 18.9 14.1 High Efficiency 57.0 50.0 25.0 25.0 20.0 Premium Efficiency 57.0 49.0 24.5 24.5 18.9 High Efficiency 69.8 62.0 31.0 31.0 24.3 Premium Efficiency 70.5 61.0 30.5 30.5 24.2 a. 460/60/3 motors are used. Derate nameplate horsepower to 0.83 to obtain actual horsepower. Supply Power Wiring 1. Units require three-phase power supply. 2. Allowable voltage tolerances: a. 60 Hertz Nameplate 208V: Min.187V, Max. 229V Nameplate 230V: Min.207V, Max. 253V Nameplate 460V: Min.414V, Max. 506V Nameplate 575V: Min.518V, Max. 632V b. 50 Hertz Nameplate 400V: Min. 342V, Max. 418V 3. Power lead wire sizing: a. For units with cooling capability (all concurrent loads) with or without hot water heating and circuits with motor loads only: MCA = 1.25 (largest motor RLA or FLA) + other loads + 2 amps. b. For units with cooling capability and non concurrent electric heat capability: In the cooling mode, the loads will be composed of supply fan motor and compressors. In heating mode, the loads will be composed of supply fan motor and electric heater. The MCA is calculated for unit running in either mode; the highest value obtained is used for the MCA. (1) For unit in cooling mode: MCA = 1.25 (largest RLA or FLA) + other loads + 2 amps. (2) For unit in heating mode: MCA = 1.25 (electric heat FLA + Fan FLA) + 2 amps. 4. Size wires in accordance with Table 310-16 or 310-19 of the National Electrical Code. 5. Wires should be sized for a maximum of 3% voltage drop. Lug Sizes For Single Disconnect or Power Block Table 10. Single Disconnect UNIT VOLTAGE SIZE (AMPS) 018-028 208/230 225 018-028 400/460 100 018-028 575 100 035-040 208/230 225 035-040 400/460 150 035 575 100 040 575 150 Table 11. Lug Sizes For Single Disconnect DISCONNECT SIZE LUG SIZE 100 #6-2/0 150 #2-3/0 225 #3-300 MCM Table 12. Lug Sizes For Power Block UNIT VOLTAGE LUG SIZE 018-040 ALL #6-400 MCM 20 IM709
Control Center All electrical controls are enclosed in a central control center located at the front of the unit. The control center is divided into two separate compartments, high and low voltage. The lower compartment houses the high voltage components and can be accessed through the Electrical Access" panels indicated on the dimensional drawing. Behind these access panels are hinged dead front panels for further operator protection. High voltage components include: 1. Fan Motor Contactor, M30 2. Fan Motor Overload, OL10 3. Fan Motor Fuse, FB10 4. Compressor Contactors, M1-M6 5. Compressor Fuses, FB1-FB6 6. Electric Heat Contactors, M11-M16 7. Transformer, T1, T2, T3 8. Disconnect Switch, DS1-DS2 9. Power Block, PB1-PB2 If the optional disconnect switch is provided, the switch handle is visible and accessible without removing any safety or access panels. Low voltage components are located in the upper left compartment, and include: 1. MicroTech II Main Control Board, MCB 2. Duct Static Pressure Sensor, SPS1 3. Optional 2nd Duct Static Pressure Sensor, SPS2 4. Optional BACNet Ethernet Communication Card, 5. Optional BACNet MSTP Communication Card, 6. Optional LonMark Communication Card, 7. Compressor Control Board, CCB #1 8. Compressor Control Board, CCB #2 Located on the face of the unit is the interactive MicroTech II keypad/display, unit switch, system indicator light and power indicator. Note: IM710 has additional layout of the control center. Figure 18. Typical Control Center Layout High and Low Voltage Compartments LonMark Communication Card BACNet Communication Card Phase Voltage Disconnect Switch Monitor (Optional) Power Block Adjustable Frequency Drive (Optional) Transformer, Control Output, 24V, T3 Transformer, Control Output, 24V, T2 Duct Static Pressure Sensor, SPS1 Transformer, Main Control, 115V, T1 IM709 21
Electrical Legend Designation Description Standard Location Designation Description Standard Location ACT1 ACTUATOR,VARIABLE INLET VANES SUPPLY FAN SECTION OAE OUTSIDE AIR ENTHALPY EXTERNAL ACT2 ACTUATOR,BYPASS CONDENSER OAT OUTSIDE AIR TEMP. SENSOR EXTERNAL ACT3 ACTUATOR,WATERSIDE ECONOMIZER WATERSIDE ECONO OL10 OVERLOAD RELAY--SUPPLY FAN MAIN CONTROL AFD10 ADJUST.FREQUENCY DRIVE--SUPPLY FAN MAIN CONTROL PB1 POWER BLOCK--TOTAL UNIT OR MAIN CONTROL COMPR/HEAT CCB1,2 COMPR CONTROL BOARDS--REFRIG. CIR- MAIN CONTROL PB2 POWER BLOCK--SAF/RAF/CONTROLS MAIN CONTROL CUITS COMPR#1-6 COMPRESSORS #1--6 COMPRESSOR SEC- PC5 PRESSURE CONTROL--CLOGGED FILTER COIL SECTION TION DAT DISCHARGE AIR TEMP. SENSOR NEAR FAN INLET PC7 PRESSURE CONTROL--PROOF AIRFLOW COIL SECTION DHL DUCT HI-LIMIT COIL SECTION PM1 PHONE MODEM MAIN CONTROL DS1 DISCONNECT--TOTAL UNIT OR MAIN CONTROL PSR1,2 PRESSURE SENSOR,REFRIGERANT LIQ. SHUTOFF S COND/HEAT DS2 DISCONNECT--SAF/RAF/CONTROLS MAIN CONTROL PVM1 PHASE VOLTAGE MONITOR MAIN CONTROL EWT ENT. COND. WATER SENSOR COND. WATER INLET PVM2 PHASE VOLTAGE MONITOR MAIN CONTROL F1 FUSE--CONTROL CIRCUIT MAIN CONTROL R11 RELAY--ELECTRIC HEAT STAGE 1 HW/S MAIN CONTROL CLOSE FB10 FUSEBLOCK--SUPPLY FAN MAIN CONTROL R12 RELAY--ELECTRIC HEAT STAGE 2 HW/S MAIN CONTROL OPEN FB11,12 FUSEBLOCKS--ELECTRIC HEAT MAIN CONTROL R1-6 RELAYS--HI-PRESSURE MAIN CONTROL FB1--6 FUSEBLOCKS--COMPRESSOR #1-6 MAIN CONTROL R18 RELAY--COOL ENABLE MAIN CONTROL FB8 FUSEBLOCK--MAIN TRANSFORMER MAIN CONTROL R67 RELAY--ENABLE SUPPLY FAN MAIN CONTROL FP1-6 FROST PROTECTION--REFRIG. CIRCUITS EVAP. COIL RAE RETURN AIR ENTHALPY EXTERNAL FS1 FREEZESTAT CONTROL BT/DT COIL RAT RETURN AIR TEMP. SENSOR EXTERNAL GRD GROUND ALL CONTROL BOX S1 SWITCH--SYSTEM ON/OFF MAIN CONTROL HL13-14 HI-LIMITS, PWR, ELEC HEATERS ELECTRIC HEAT S4,5 SWITCHES--INVERTER BYPASS MAIN CONTROL JCT.BOX HP1-6 HI-PRESSURE CONTROLS, REFRIG ON COMPRESSORS S7 SWITCH--LOCAL ON/OFF TO CONTROLLER MAIN CONTROL #1-6 HTR-11,12 ELECTRIC HEATERS DX COIL S8 SWITCH--COOL ENABLE MAIN CONTROL HTR-15,16 ELECTRIC HEATERS DX COIL S9 SWITCH--HEAT MAIN CONTROL HTR1-6 CRANKCASE HEATERS ON COMPRESSORS SD1 SMOKE DETECTOR--SUPPLY FAN EXTERNAL #1-6 HUM1 HUMIDSTAT SENSOR EXTERNAL SD2 SMOKE DETECTOR--RETURN FAN EXTERNAL LP1-6 LO-PRESSURE CONTROLS, REFRIG ON COMPRESSORS SPS1,2 STATIC PRESSURE SENSORS--DUCT/BLDG MAIN CONTROL #1-6 LWT LEAVING COND. WATER SENSOR COND. WATER OUTLET T1 TRANSFORMER--MAIN CONTROL MAIN CONTROL (LINE/115V) M10 CONTACTOR--SUPPLY FAN MAIN CONTROL T2 TRANSFORMER--CONTROL INPUT 24V MAIN CONTROL M11,12 CONTACTORS--ELECTRIC HEAT CONTROL MAIN CONTROL T3 TRANSFORMER--CONTROL OUTPUT 24V MAIN CONTROL M13,14 CONTACTORS--ELECTRIC HEAT SAFETY MAIN CONTROL TB10 TERMINAL BLOCK-- MAIN CONTROL M15,16 CONTACTORS--ELECTRIC HEAT CONTROL MAIN CONTROL TB2 TERMINAL BLOCK--24V-FACTORY/FIELD MAIN CONTROL M1-6 CONTACTORS--COMPR#1-6 MAIN CONTROL TB3 TERMINAL BLOCK--24V- MAIN CONTROL M17,18 CONTACTORS--ELECTRIC HEAT SAFETY MAIN CONTROL TB4 TERMINAL BLOCK--24V-COMPRESSOR MAIN CONTROL M30 CONTACTOR--INVERTER BYPASS MAIN CONTROL TB5 TERMINAL BLOCK--115V-FACTORY/FIELD MAIN CONTROL MAT MIXED AIR TEMP SENSOR BEHIND FILTERS TB6 TERMINAL BLOCK--115V/24V FACTORY MAIN CONTROL MCB1 MICROPROCESSOR CIRCUIT BOARD #1 MAIN CONTROL TB8 TERMINAL BLOCK-- MAIN CONTROL MJ MECHANICAL JUMPERS ON TEMINAL BLOCKS VM1 MOTOR #1--HEATING NEAR HOT WATER INLET MP1-6 MOTOR PROTECTOR--COMPR#1-6 ON COMPRESSORS VM5 MOTOR #5--COOLING NEAR CHILLED WATER #1-6 NB1 NEUTRAL BLOCKS MAIN CONTROL WF1 CONDENSER WATER FLOW SWITCH NEAR CONDENSER ZNT1 ZONE TEMP. SENSOR--SETBACK FIELD INSTALLED 1. 2. 3. 4. 5. 6. 200 FIELD WIRING TERMINAL FIELD WIRING TERMINAL TERMINAL P.C. BOARD FACTORY WIRED WIRE NUMBER WIRE CONNECTOR 7. 8. OPTION BLOCK PLUG IN CONNECTOR 9. M/J MECHANICAL JUMPER 22 IM709
Typical Wiring Schematics Figure 19. Power Schematic IM709 23
Figure 20. Input Schematic, Discharge Air Control (DAC) 24 IM709
Figure 21. Input Schematic, Zone or Space Comfort Control (SCC) IM709 25
Figure 22. Output Schematic, Actuator Control 26 IM709
Figure 23. Output Schematic, Auxiliary Fan Start/Stop Control IM709 27
Figure 24. Output Schematic, Actuator Control 28 IM709
Figure 25. Output Schematic, Compressor Control (4 Compressors /4, 5 or 6 Stage) IM709 29
Standard Controls High Pressure Switches The high pressure switch (HP1-HP4) is a single pole pressure activated device that opens on a pressure rise. When the switch opens it de-energizes the compressor circuit, shutting down the compressor. The MicroTech II controller will display an alarm condition. Once the cause of the fault has been identified and corrected the unit may be manually reset through the MicroTech II keypad/display interface. The high pressure switch is located at the top of the compressor on the discharge connection. To check the control, shut off water flow to the condensers and observe the cutout point on a high pressure gauge. The high pressure control should open at 360 psig and close at 300 psig. After testing the high pressure control, check the pressure relief device for leaks. Low Pressure Switches The low pressure switch (LP1 -LP4) is a single pole pressure activated device which closes on a pressure rise. It senses evaporator pressure and is factory set to close at 60 psig and open at 35 psig. Compressor operation is not allowed until the switch closes. The low pressure switch is an automatic reset control. If the condition occurs on any one compressor three times in a 24-hour period, the alarm will have to be manually reset through the MicroTech II keypad/display interface to restart the compressor. The low pressure switch is located at the bottom of the compressor on the suction connection. Compressor Motor Protector All compressors are thermally protected. All 10 horsepower and larger compressors use a solid state protection device (MP1 - MP4) located in the compressor junction box. Whenever the protection system opens the compressor is shut down for a period of four minutes and an alarm indication is made at the MicroTech II controller. All 5 horsepower compressors have in-line protection. The control automatically resets when the alarm condition is removed and the time delay is satisfied. If the condition occurs on any one compressor three times in a 24-hour period, the alarm will have to be manually reset through the MicroTech II keypad/display interface to restart the compressor. Proof of Airflow Switch A positive proof of airflow switch (PC7) is provided with all units. The switch is factory set to close at 0.2 inches of H 2 O. The switch has a field adjustable set point range of 0.17 to 5.0 inches of H 2 O. Turn adjustment screw clockwise to decrease differential pressure setting. Turn adjustment screw counterclockwise to increase differential pressure setting. In a constant volume system, if the fan system is energized and the minimum pressure setting of the switch has not been reached, the unit will be shut down and a loss of airflow alarm indicated at the MicroTech II controller. For variable air volume units, the unit will shutdown due to loss of airflow only if the airflow switch is open and the duct static pressure is less than half the duct static pressure setpoint. Once the reason for the fault has been corrected, the unit can be manually reset through the MicroTech II keypad/display interface. PC7 is located in the coil section on the back side of the control panel. Frost Protection Switches A frost protection switch (FP1 -FP4) is used on each refrigerant circuit to protect against evaporator coil freeze up. The frost protection switches are normally closed and open on a drop in temperature. When a frosting condition is sensed the compressor circuit is shutdown until the condition has been removed. The frost protection control is an automatic resetcontrol. If the condition occurs on any one compressor three times in a 24 hour period, the alarm will have to be manually reset through the MicroTech II keypad/display interface to restart the compressor. The MicroTech II control will indicate a warning when a frost condition exists. The temperature sensors are located on a return bend for each refrigerant circuit. Clogged Filter Switch A clogged filter switch (PC5) is provided to indicate when the unit filters are to be changed. The switch is factory set to close at 0.6 inches of H 2 O. The switch has a field adjustable set point range of 0.17 to 5.0 inches of H 2 O. Turn adjustment screw clockwise to decrease differential pressure setting. Turn adjustment screw counterclockwise to increase differential pressure setting. When the filter pressure differential exceeds the switch setpoint, a clogged filter indication is made at the MicroTech II controller. The unit is allowed to continue operation. PC5 is located in the coil section on the back side of the control panel. 30 IM709