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Installation & Maintenance Data
Group: WSHP
Part Number: 910115865
Date: July 2011
IM 1056
©2011 McQuay International
®
Model RWA
McQuay Rooftop Water Source Heat PumpsModel RWA, RGA – Downflow Discharge and ReturnModel, RWC, RGC – Horizontal Discharge and Return
Unit Sizes 036 – 420 • R-410A Refrigerant
Page 2 of 24 / IM 1056
Table of Contents
Model Nomenclature
W RWA 2 036 E F Y
Product CategoryW = WSHP
Product IdentifierRWA = Rooftop Downflow Water Source Heat PumpRWC = Rooftop Horizontal Water Source Heat PumpRGA = Rooftop Downflow WSHP (Geothermal Unit)RGC = Rooftop Horizontal WSHP (Geothermal Unit)
Design Series1 = 1st Design2 = 2nd Design3 = 3rd Design4 = 4th Design
Nominal Capacity036 = 36,000 Btuh Nominal Cooling048 = 48,000 Btuh Nominal Cooling060 = 60,000 Btuh Nominal Cooling072 = 72,000 Btuh Nominal Cooling084 = 84,000 Btuh Nominal Cooling096 = 96,000 Btuh Nominal Cooling120 = 120,000 Btuh Nominal Cooling150 = 150,000 Btuh Nominal Cooling180 = 180,000 Btuh Nominal Cooling210 = 210,000 Btuh Nominal Cooling 200 = 200,000 Btuh Nominal Cooling240 = 240,000 Btuh Nominal Cooling300 = 300,000 Btuh Nominal Cooling360 = 360,000 Btuh Nominal Cooling420 = 420,000 Btuh Nominal Cooling
Cabinet HeightY = None
VoltageF = 208-230/60/3K = 460/60/3L = 575/60/3
ControlsE = Electromechanical
Note: For illustration purposes only. Not all options available with all models.
PleaseconsultMcQuaySalesRepresentativeforspecificavailability.
Model Nomenclature ...........................................................2Receiving..............................................................................3Safety Information ...............................................................4
Safety Labeling and Signal Words ....................................4
Introduction ..........................................................................5Design Certification...........................................................5Codes and Ordinances .....................................................5Service Clearances...........................................................5Curb Installation, Protrusions............................................5
Physical Data .......................................................................6Rigging .................................................................................7
Rigging Removal ..............................................................7
Electrical............................................................................7-8Main Power Wiring............................................................7Control System Wiring ......................................................8
Ductwork ..............................................................................8
Condensate Piping ..............................................................8Water Connections .........................................................8-10Cooling Systems Options .................................................11
Hot Gas Bypass ..............................................................11Water Regulating Valve ..................................................11Adjustable High and Low Pressure Switches .................11To Measure Water Flow: ................................................11
Start-up Instructions (Water Source) .........................11-12Mechanical Adjustments .............................................12-13
Set Fan RPM ..................................................................12Fan Rotation Check ........................................................12Drive Belt Tension and Alignment ...................................13Electrical Systems Options .............................................14
Wiring Diagrams ................................................................14Maintenance Procedures ..................................................21Trouble Diagnosis ........................................................21-23
IM 1056 / Page 3 of 24
IMPORTANT This product was carefully packed and thoroughly inspected
before leaving the factory. Responsibility for its safe delivery was assumed by the carrier upon acceptance of the shipment. Claims for loss or damage sustained in transit must therefore be made upon the carrier as follows:
VISIBLE LOSS OR DAMAGE
Any external evidence of loss or damage must be noted on the freight bill or carrier’s receipt, and signed by the carrier’s agent. Failure to adequately describe such external evidence of loss or damage may result in the carrier’s refusal to honor a damage claim. The form required to file such a claim will be supplied by the carrier.
CONCEALED LOSS OR DAMAGE
Concealed loss or damage means loss or damage which does not become apparent until the product has been unpacked. The contents may be damaged in transit due to rough handling even though the carton may not show external damages. When the damage is discovered upon unpacking, make a written request for inspection by the carrier’s agent within fifteen (15) days of the delivery date and file a claim with the carrier.
WARNING This Installation and Maintenance bulletin is intended to provide
the proper procedures for installing a McQuay Rooftop Water Source Heat Pump. Failure to follow these procedures can cause property damage, severe personal injury or death. Ad-ditional, failure to follow these procedures can cause premature failure of this equipment or cause erratic unit operation, resulting in diminished unit performance.
ReceivingUpon receipt of the equipment, check carton for visible damage. Make a notation on the shipper’s delivery ticket before signing. If there is any evidence of rough handling, immediately open the cartons to check for concealed damage. If any damage is found, notify the carrier within 48 hours to establish your claim and request their inspection and a report. The Warranty Claims Department should then be contacted.Do not stand or transport the machines on end. For storing, each carton is marked with “up” arrows.In the event that elevator transfer makes up-ended positioning unavoidable, do not operate the machine until it has been in the normal upright position for at least 24 hours.Temporary storage at the job site must be indoor, completely sheltered from rain, snow, etc. High or low temperatures natu-rally associated with weather patterns will not harm the units. Excessively high temperatures, 140°F (60°C) and higher, may deteriorate certain plastic materials and cause permanent damage.
Receiving
Page 4 of 24 / IM 1056
DANGER – Product LabelingWhite lettering on a black background except the wordDANGER which is white with a red background.
Warning Label – Product LabelingWhite lettering on a black background except the wordWARNING which is white with an orange background.
WARNING This unit contains HFC-(R410A), an azeotropic mixture of R-32
(Difluoromethane) and R-125 (Pentafluoroethane). DO NOT VENT HFC-(R410A) to the atmosphere. The U. S. Clean Air Act requires the recovery of any residual refrigerant. Do not use R-22 service equipment or components on R410A systems.
CAUTION
WARNING
Safety Information
Safety Labeling and Signal WordsDanger, Warning and Caution
The signal words DANGER, WARNING and CAUTION are used to identify levels of hazard seriousness. The signal word DANGER is only used on product labels to signify an im-mediate hazard. The signal words WARNING and CAUTION will be used on product labels and throughout this manual and other manuals that may apply to the product.
Signal WordsDANGER – Immediate hazards which WILL result in severe personal injury or death.
WARNING – Hazards or unsafe practices which COULD result in severe personal injury or death.
CAUTION – Hazards or unsafe practices which COULD result in minor personal injury or product or property damage.
Signal Words in ManualThe signal word WARNING is used throughout this manual in the following manner:
WARNINGThe signal word CAUTION is used throughout thismanual in the following manner:
CAUTIONCAUTION – Product LabelingSignal words are used in combination with colors and/or pictures on product labels. Following are examples of product labels with explanations of the colors used.
IM 1056 / Page 5 of 24
Introduction
IntroductionModels RWA, RGA, RWC, RGC, packaged cooling and heating units are designed to heat or cool a conditioned space with mechanical refrigeration. The cabinet design provides space for a number of options. Most of these options will be covered in this manual; for those of a more custom nature, consult the McQuay Application Engineering Department. Model RWA, RGA, RWC, RGC units are designed for roof-top curb, slab mounted or installed on post and rail applica-tions. Horizontal discharge with 100% outside air does not require a curb and may be slab mounted. A 14" high or 24" high insulated roof curb is sold separately as a field-installed accessory.
Design CertificationAll units are certified by Electrical Testing Laboratories (E.T.L.) under ANSI/UL 1995.
Codes and OrdinancesThese units must be installed in accordance with the standard of the National Fire Protection Association. Local authorities having jurisdiction should be consulted before installations are made to verify localcodes and installation procedures.All field wiring to the unit must be done in accordance with these instructions, the National Electric Code (ANSI/NFPA 70-1981) in the United States and all local codes and ordi-nances.Installation should be done by a qualified agency in accor-dance with the instructions in this manual and in compliance with all codes clearances and requirements of authorities having jurisdiction.
Service ClearancesA 36" clearance must be allowed for access to the compressor and electrical panel. Do not locate the unit under an overhang that will short circuit hot air to the coil intakes.When installed at ground level, the unit should be mounted on a level concrete slab which should extend at least 2" beyond the unit on all sides. The top of the slab should be 2" above the ground level. The depth of the slab below the ground level and its structural design is governed by the type of soil and climatic conditions. The slab must not be in contact with any part of the building wall or foundation. The space between the slab and building wall prevents the possibility of transmitting vibration to the building. The dimensions of the slab or roof mount should be checked and verified before the equipment arrives. Unit supports, roof opening, roof curb flashing, drain requirements, and electric locations are important to a good installation.
When installing the equipment on top of a building, the fol-lowing should be considered. Structural members supporting the unit must be sufficiently strong for the weight of the unit and mounting rails. Transmission of sound into the building is sometimes a problem when the structure is not strong enough.Locate the unit as near as possible to the center of the area to be environmentally controlled. Sufficient clearance must be available for service, edge of roof, other units, or hazards. The condenser air inlet and discharge air must be unobstructed by overhang, walls, or other equipment. Avoid locations next to exhaust fans or flues.Select a location where external water drainage cannot collect around the unit. Locate the unit so roof runoff water does not pour directly on the unit. Provide gutter or other shielding at roof level.Where snowfall is anticipated, mount the unit above the maximum snow depth for the area.
Curb Installation, ProtrusionsProper installation of the RWA, RGA, RWC, RGC units requires that the roof mounting of the curb be firmly and per-manently attached to the roof structure. Check for adequate fastening method prior to setting rooftop unit on curb.Inspect curb to insure that none of the utility services (elec-tric, gas, drain lines) routed through the curb protrude above the curb. Being a fully welded solid bottom curb, duct con-nections can be made before unit is set on curb. Duct open-ings are to be sized and cut by the installing contractor in the solid curb.
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Physical DataTable 1: RWH, RGA, RWC, RGC 036 - 084
Description Unit Size
036 048 060 072 084 Fan Wheel - Diameter × Width (Inches) 12 × 9 12 × 9 12 × 9 12 × 9 12 × 9 Fan Quantity 1 1 1 1 1 1/2 ● n/a n/a n/a n/a 3/4 ● ● ● ● n/a
Fan Motor Horse Power (HP) 1 ● ● ● ● n/a
1-1/2 ● ● ● ● ● 2 ● ● ● ● ● 3 n/a ● ● ● ● 5 n/a n/a n/a n/a ● Coil Face Area (Sq Ft) 4 4 4 7-1/2 7-1/2 Coil Rows 4 4 4 4 4 Compressor Type (Quantity) Scroll (1) Scroll (1) Scroll (1) Scroll (1) Scroll (1) Filter - Quantity-Size 4- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2 Water Connections O.D. Sweat 7/8 1-1/8 1-3/8 1-3/8 1-3/8 Condensate Connection Size (MPT) - (Quantity) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) Operating Weight 1490 1540 1590 1630 1650 Shipping Weight 1490 1540 1590 1630 1650 14" 1765 1815 1865 1905 1925
Curb Weight + Unit Weight 24" 1865 1915 1965 2005 2025
Table 2: RWH, RGA, RWC, RGC 096 - 210
Description
Unit Size 096 120 150 180 210 Fan Wheel - Diameter × Width (Inches) 12 × 12 12 × 12 15 × 15 15 × 15 15 × 15 Fan Quantity 1 1 1 1 1 1 ● n/a n/a n/a n/a 1-1/2 ● ● n/a n/a n/a 2 ● ● n/a n/a n/a Fan Motor Horse Power (HP) 3 ● ● ● n/a n/a 5 ● ● ● ● ● 7-1/2 n/a ● ● ● ● 10 n/a n/a ● ● ● Coil Face Area (Sq Ft) 12 12 12 12 12 Coil Rows 4 4 4 4 6 Compressor Type (Quantity) Scroll (2) Scroll (2) Scroll (2) Scroll (2) Scroll (2) Filter - Quantity-Size 4- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2 Water Connections O.D. Sweat 1-5/8 1-5/8 1-5/8 1-5/8 1-5/8 Condensate Connection Size (MPT) - (Quantity) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) Operating Weight 1750 1800 1860 1900 1920 Shipping Weight 1750 1800 1860 1900 1920 14" 1765 1815 1865 1905 1925
Curb Weight + Unit Weight 24" 1865 1915 1965 2005 2025
Table 3: RWH, RGA, RWC, RGC 200 - 420
Description Unit Size
200 240 300 360 420 Fan Wheel - Diameter × Width (Inches) 15 × 15 18 × 18 18 × 18 18 × 18 18 × 18 Fan Quantity 1 1 1 1 1 3 ● n/a n/a n/a n/a 5 ● ● ● n/a n/a Fan Motor Horse Power (HP) 7-1/2 ● ● ● ● n/a 10 ● ● ● ● ● 15 n/a ● ● ● ● 20 n/a n/a n/a ● ● Coil Face Area (Sq Ft) 23 23 23 23 23 Coil Rows 4 4 4 4 6 Compressor Type (Quantity) Scroll (2) Scroll (2) Scroll (2) Scroll (2) Scroll (4)
Filter - Quantity-Size (1) 2- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2 4- 20 × 24 × 2
4- 24 × 24 × 2 4- 24 × 24 × 2 4- 24 × 24 × 2 4- 24 × 24 × 2 4- 24 × 24 × 2 Water Connections O.D. Sweat 2-1/8 2-1/8 2-1/8 2-1/8 2-1/8 Condensate Connection Size (MPT) - (Quantity) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) 1-1/4 (1) Operating Weight 3150 3200 3300 3380 3800 Shipping Weight 3150 3200 3300 3380 3800 14" 3455 3505 3605 3685 4105
Curb Weight + Unit Weight 24" 3575 3625 3725 3805 4225
Installation
IM 1056 / Page 7 of 24
Rigging
WARNING Be sure that the crane and lift material (bars, cable, chain), (or
other lifting device) capacity is adequate for the unit weight. The total unit weight calculated must include all appropriate options for your unit. Certain options can add significant weight to a unit.
See Table 1, Table 2 & Table 3 for unit weights. Spreader bars keep the lift cables from damaging the cabinet once the unit has been lifted, these bars will be required in all instances (Figure 1). Keep the tension equal, improper lift tension can damage wiring, refrigeration lines and the water tight integrity of the cabinet as well as sheet metal damage to the unit cabinet.Figure 1: Typical Crane Lift
Spreader BarH-type (Required)
Lower unit carefully onto roof mounting curb or mounting rails or ground level slab. While rigging unit, center of grav-ity will cause condenser end to be lower than supply/return air end. Bring condenser end of unit into alignment with curb. With condenser end of unit resting on curb member and using curb as fulcrum, lower front end of unit until entire unit is seated on curb.
Rigging RemovalRemove spreader bars, lifting cables and other rigging equip-ment. Use caution not to dent scratch or otherwise damage cabinet or intake and exhaust hoods.
CAUTION Do not allow crane hooks and spreader bars to rest on roof of
the unit.
Installation
ElectricalWiring ConnectionsPower wiring should be connected to the main power terminal block located within the unit main control section. Power wir-ing connections on units with factory disconnects should be made at the line side of the disconnect switch.Low voltage wiring connections are made to the remote mounted controller or time clock.DO NOT TAMPER WITH FACTORY WIRINGContact your local representative or the factory if assistance is required. The internal power and control wiring of these units is factory installed and each unit is thoroughly tested prior to shipment.
Independent Power SourceIt is recommended that an independent 115-volt power source be brought to the vicinity of the rooftop unit for portable lights and tools used by the service mechanic.
Main Power WiringThe units are factory wired for the voltage shown on the nameplate.Main power wiring should be sized for the minimum wire ampacity shown on the nameplate. An external weather-tight disconnect switch properly sized for the unit total load is required for each unit. Disconnect must be installed in accor-dance with Local and/or National Electric Codes.Power wiring may enter the Rooftop Unit through the through the unit base and roof curbs on all models. Install conduit connectors at the entrance locations. External connectors must be weatherproof.
GroundingAll units must be properly grounded. The ground lug is provided for this purpose. DO NOT use the ground lug for connecting a neutral conductor. The unit must be electrically grounded in accordance with local codes, or in the absence of local codes, with the NEC ANSI/NFPA 70 1981.Once it is established that supply voltage is within the utiliza-tion range, check and calculate if an unbalanced condition exists between phases. Calculate percent voltage unbalance as follows:Percent Maximum Voltage DeviationVoltage = 100 × From Average VoltageUnbalance Average Voltage
Example: With voltage of 220, 215 and 210 Average voltage = 220 + 215 + 210 = 645 ÷ 3 = 215 Maximum voltage deviation from Average voltage = 220 – 215 = 5
Percent = 5 500 = 2.3%* Voltage 215
– 215
*Percent voltage unbalance must not exceed 2%
Note: Contact power company if phase unbalance exceeds 2%.
Page 8 of 24 / IM 1056
Installation
Control System WiringFor commercial equipment the following table lists the mini-mum size of 24-volt class 2 wire to be used.Table 4: Control System Wiring Wire Size Ft. Run From Unit to Thermostat or Longest Run 18 AWG Maximum Run 50 Feet 16 AWG Maximum Run 75 Feet 14 AWG Maximum Run 100/125 Feet 12 AWG Maximum Run 150/200 Feet
Note: Wiring - Consult the wiring diagram furnished with the unit. These units are custom designed for each application. The unit wiring diagram is located inside the control panel of each unit.
DuctworkProperly sized and installed ductwork is critical to reliable performance of the unit and system. Complete Down flow (vertical) and horizontal supply or (horizontal) supply and return duct connections with the use of a tall horizontal duct curb. All duct connections with the use of a curb are to be field sized and cut. All ductwork must be installed according to local codes, practices and requirements.Industry manuals should be used as a guide to sizing and de-signing the duct system. Ducts passing through unconditioned spaces must be well insulated with vapor barrier to prevent condensation.
Condensate PipingA condensate trap must be provided by customer. Drainage of condensate directly onto the roof is acceptable if permitted by local codes. It is recommended that a small drip pad of either stone, or tar, wood or metal be provided to prevent any pos-sible damage to the roof. If condensate is to be piped into the building drainage system, the drain line must penetratethe roof external to the unit. Refer to local codes for addi-tional requirements.
Figure 2: Condensate Drain Details
Table 5: Schedule 40 Condensate Drain Pipe Dimensions Size Nominal Diameter Wall Outside Inside Thickness 3/4" 1.050" 0.824" 0.113" 1" 1.315" 1.049" 0.133" 1-1/4" 1.660" 1.380" 0.140" 1-1/2" 1.900" 1.610" 0.145" 2" 2.375" 2.067" 0.154" 2-1/2" 2.875" 2.467" 0.203" 3" 3.500" 3.068" 0.216"
Figure 3: Schedule 40 Pipe & Trap Size Specifications
Note: The trap must be primed before operating unit.
Figure 4: Drain Trap Details
Water ConnectionsWater connections are inside the unit, in the compressor compartment. There are two pipe sleeves in the bottom pan of the unit, and the water lines must be brought up to the roof through the curb. Dimensions locating the sleeve centerlines are shown in Figure 7 & Figure 8 on page 10.Where the two condensers are used, they are manifolded at the factory, so only two connections are required in the field.
IM 1056 / Page 9 of 24
InstallationFollow all local plumbing codes in connecting water lines, and insulate against freezing. Most of these units will be installed on closed loop systems. If well water is used, an adequate supply of good water must be available. If it is high in mineral content, it may need to be treated to keep the heat exchanger from "liming up". If high in sulfur content, an optional Cupronickel condenser may need to be specified. Consult local water treatment companies for advice on the condition of the water you intend to use.To measure water flow: Pressure taps are provided on each water connection, in order to measure water pressure at the inlet and outlet. This will allow the pressure drop across the unit to be determined, and the unit specification sheet will indicate water flow in GPM.Rated flow in accordance with applicable ARI standards is that rate which gives a 10 degree F. water temperature rise on the cooling cycle, at rated CFM, 80°F. dry bulb and 6°F. wet bulb air across the evaporator coil (see unit specification sheet).
However, for most closed loop applications, the recommend-ed flow rate will vary according to inlet water temperature. The O.D. sweat water connections are stubbed off horizon-tally inside the condensing section.The water piping can be turned down to go through the sleeve for the water connections or they can be routed horizontally and come out on the side of the cabinet. Openings must be cut in the roof curb where the water lines are to pass down through the curb opening. Typically these holes are cut below the condenser section where the water sleeves are located (see Figure 5 & Figure 6). Also refer to Figure 7 & Figure 8 on page 10.For a horizontal option, holes must be cut for the water in and out tubing. These are typically made in the corner posts.
Figure 5: 14" Curb Supply & Return Water Piping Locations – Unit Sizes 036-210
Figure 6: 24" Curb Supply & Return Water Piping Locations – Unit Sizes 200-420
Page 10 of 24 / IM 1056
Figure 7: Top-Down View of Unit Size 036-210 & Curb Dimension Details
Water Coil Connections (O.D. Sweat)Size 036 = 7/8" Size 048 = 1-1/8" Size 060, 072, 084 = 1-3/8" Size 096, 120, 150, 180, 210 = 1-5/8"
Figure 8: Top Down View of Unit Sizes 200-420 & Curb Dimension Details
Water Coil Connections (O.D. Sweat)Size 200, 240, 300, 360, 420 = 2-1/8"
Installation
IM 1056 / Page 11 of 24
Installation
Figure 9: Access, Service & Maintenance Clearance
24" - 36"
48"
Control Panel
Filter Access
Outside AirIntake Hood
CondensateDrain Pan
Supply Fan
48"
36"
Table 6: Unit Clearances Required Clearances
Model Sides* Bottom
Top Control Opposite To To Non- Combustibles Combustibles RWA RGA 36" 48" 36" 24" 0" RWC RGC
Cooling Systems OptionsHot Gas BypassHot gas bypass is a means of capacity control during lower ambient temperature conditions. The Hot Gas Bypass valve is an adjustable valve and should be set to open when the re-frigerant suction pressure drops to 107-112 psig. It varies unit capacity by introducing discharge refrigerant into the evapo-rator circuit where it creates a false evaporator load. The hot gas is cooled prior to its return to the compressor as it passes through the evaporator.The Hot Gas Bypass Solenoid Valve is energized through the thermostat and routs discharge gas to the hot gas bypass valve. It is de-energized during the pump down cycle.
Water Regulating ValveA water regulating valve modulates water flow to maintain a discharge pressure between 295 psig and 10 psig.
Adjustable High and Low Pressure SwitchesStandard cooling units are equipped with non-adjustable pres-sure switches. The low pressure switch is set to open at 135± psig and is an automatic reset switch closing at 99± psig. The high pressure switch is set to open at 640± psig and is a manual reset switch set to close at 595± psig.Units can be equipped with adjustable high and low pressure switches for those installations that require finer settings than the non-adjustable switches provide. Low pressure switches have both set point and differential adjustments and are automatic reset. High pressure switches must not be set above 640 psig and are manual reset. Set point and differential are adjustable.
To Measure Water Flow: Pressure taps are provided on each water connection, in order to measure water pressure at the inlet and outlet. This will allow the pressure drop across the unit to be determined, and the unit specification sheet will indicate water flow in GPM. Rated flow in accordance with applicable ARI standards is that rate which gives a 10 degree F. water temperature rise on the cooling cycle, at rated CFM, 80°F. dry bulb and 67°F. wet bulb air across the evaporator coil (see unit specification sheet). However, for most closed loop applications, the recommend-ed flow rate will vary according to inlet water temperature.
Start-up Instructions (Water Source) The following steps are offered as a general guide to start-up: a. With a voltmeter, check to see that the voltage to be
applied to the unit is correct. If it is low by more than 10%, consult the power company before starting the unit. If it is high, watch carefully to see that it does not remain more than 10% high during full load running conditions.
b. ALL UNITS ARE EQUIPPED WITH COMPRESSOR CRANKCASE HEATERS, WHICH MUST BE ENERGIZED AT LEAST 12 HOURS PRIOR TO START-UP.
Before turning power on to the unit, see that the thermostat switch is in the OFF position. Then turn power on. Allow it to remain on at least prior to starting the unit.
c. Feel the compressor crankcase. It should be warm, since the heaters have been on at least 12 hours. This will assure that no refrigerant liquid is present in the crankcase. If the crankcase is allowed to contain liquid refrigerant, compressor damage or failure can occur on start-up.
d. Install suction and discharge gauge set on compressor, to read suction and discharge pressure.
e. Turn the thermostat Fan Switch to the ON position. The supply air blower should operate. Observe that airflow is present. Measure that airflow in order to determine if it is as specified for the particular application. Normal methods of measurement should be used, as with any commercial installation. Since blower motor is three-phase, check to be sure it is not running backwards. If it is, interchange any two of the three power leads to the unit, after first stopping the unit and opening the disconnect to remove power from the unit.
f. Be sure that water flow to the unit is correct. Section VIII gives correct pressure drop readings across the condenser; Schrader fittings are provided to read that pressure drop. Water flow should be as specified for the job.
Page 12 of 24 / IM 1056
Installation
g. After being satisfied that airflow and water flow are correct, turn the temperature setting on the thermostat as high as it will go. Then turn the system switch to COOL. The unit compressor should not come on yet. Then, slowly turn the temperature setting down until the thermostat contacts make, calling for cooling. The compressor should now come on. Check to see that it is operating correctly. If compressor is equipped with an oil level sight glass, check for proper oil level.
h. With a voltmeter, check to see that the unit is receiving rated voltage while running. If it remains more than 10% low or high during full load running conditions, consult the power company.
i. With an ammeter, check to see that the unit is drawing approximately rated current in amps.
j. Check pressure readings on the suction and discharge gauges. While these will vary with start-up conditions, suction pressure will usually be from 65 to 80 psig, and the discharge pressure will usually be from 210 to 240 psig. Not until the room temperature conditions have been brought to normal can you check pressures closer.
k. Check superheat at the suction line just before the compressor ... it should be about 15 degrees during normal operation.
l. After checking the cooling operation, turn the thermostat to the OFF position, and listen for the unit reversing valve to shift. Then, turn the temperature setting as low as it will go. Switch to the HEAT position. Then, gradually raise the temperature setting until the compressor comes on. See that the unit is providing heat. The unit cannot be properly checked for pressures, etc., on the heating cycle until the heating season has started and room return conditions are in the normal range of 70 degrees dry bulb. However, since the unit was factory operated in both cooling and heating, if you have correct operation in cooling, the heating operation should be satisfactory. Do not run the unit too long in heating, with high summer-time return air temperatures. Return at the beginning of the heating season to check the operation.
m. With room return air of 70 degrees dry bulb, on the heating cycle, compressor operating pressures should be: suction pressure from 60 to 70 psig, and discharge pressure from 250 to 325 psig.
n. Check to see that filters are properly positioned, and that they are clean.
o. Finally, check to see that all panels are on and correctly positioned, and that the unit seems to be operating normally, and that the owner's representative is instructed in unit operation and precautions.
Mechanical AdjustmentsSet Fan RPMAll evaporator motor sheaves are set when tested and shipped from the factory. Actual rpm must be set and verified with a tachometer. Refer to the following Blower Performance Chart for basic unit fan rpm.With disconnect switch open, place a jumper wire across Terminals R and G at TS1 Terminal Block. Close discon-nect switch; evaporator fan motor will operate so rpm can be checked.
Fan Rotation CheckCheck that fan rotates clockwise when viewed from the drive side of unit and in accordance with rotation arrow shown on blower housing. If it does not, reverse two incoming power cables at TB Terminal Block.Do not attempt to change load side wiring. Internal wiring as-sures all motors will rotate in correct direction once evapora-tor fan motor rotation check has been made.Figure 10: Fan Rotation Arrow
Forward Curve
Figure 11: Plenum Fan
Motor Sheave
Wheel Rotation
IM 1056 / Page 13 of 24
Installation
Note: To increase the blower speed, turn the outer half of the adjustable pulley clockwise. To decrease the blower speed, turn the outer half of the adjustable pulley counter clockwise.
12. Replace key if unit has keyway type pulley.13. Tighten set screw(s).14. Put on belt.15. Turn motor adjustment bolt clockwise until the belt has
enough tension at the proper deflection. Use one of the commercially available belt tension gauges to set the correct tension at the proper deflection.
16. Use a straight edge (angle iron, straight piece of board or anything with a straight surface or edge) to check the alignment of the blower pulley with blower motor pulley.
18. It may be necessary to back the tension off the belt temporarily and tighten one of the motor mount bolts before it is possible to adjust the angle of the blower motor.
19. Tighten all four blower motor mount boltFigure 12: Check Pulley Alignment
1/4" (6.4mm)*
1/4" (6.4mm)*
* Maximum Misalignment Allowed
Figure 13: Check Tension and Deflection
Drive Belt Tension and AlignmentFor ease of service RWA, RWC, RGA, RGC units are equipped with a slide out fan assembly. Two screws must be removed and the wire harness wire tie must be cut to allow the fan to slide forward.
WARNING The fan can slide completely out of the cabinet so use extreme
care not to slide fan out to a point where it could fall out of the cabinet causing severe personal injury and or equipment and roof damage. Leave at least 12 inches of the fan slide flanges engaged to the blower box rails to allow for proper support of the fan. Never apply additional weight or stand on the blower as a step!
Fan belt alignment and tension should be checked. Tension should be 3/4" depression per foot of belt span between pul-leys.
CAUTION Use extreme care during the following procedures and obey
Safety Information. Failure to do so may result in personal in-jury. The following safety rules MUST always be followed when working near belt drive.
Always Turn The Power Off1. Turn the power to the unit OFF before you begin working
on it.Always Wear Protective Clothing2. NEVER wear loose or bulky clothes, such as neckties,
exposed shirttails, loose sleeves, or lab coats around belt drives. Wear gloves while inspecting sheaves to avoid nicks, burrs, or sharply worn pulley edges.
The blower speed is changed by adjusting the variable speed pulley mounted on the blower motor.
3. Turn electric power OFF.4. Remove the side blower access panel. Loosen the four
motor mount bolts5. Turn the motor adjustment bolt counterclockwise until the
belt is slack enough to come off easily.6. Remove the belt. Do NOT pry off belt.7. Loosen set screw(s) on the outer half of the adjustable
pulley.8. The unit has one of two different types of adjustable
pulleys.9. Remove key if unit has a keyway type pulley.10. To set the blower for a desired CFM (L/s), first turn the
outer half of the adjustable pulley clockwise until it meets the inner half of the pulley.
11. Turn the outer half of the adjustable pulley counter clockwise the correct number of turns to obtain the desired CFM (L/s).
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Electrical Systems OptionsAirflow Switch – Designed to prevent system operation un-less there is proof of blower operation. A differential pressure switch measures the air pressures at the suction and discharge of the blower.Clogged Filter Indicator – Dirty or clogged filters are indi-cated when the preset pressure differential across the filters is reached. The indicator is factory installed and is manually reset. It includes contacts for remote indication.Convenience Outlet (Field Wired) – A 115V GFCI recep-tacle mounted in a 2" × 4" enclosure and is furnished with a 15 amp circuit breaker. Separate 115-volt power source and ground is required.Convenience Outlet (Factory Wired) – A 115V GFCI receptacle mounted in a 2" × 4" enclosure may be furnished with a 15 amp circuit breaker, disconnect and 1500 Watt transformer. The transformer will be field connected to the line side of the unit disconnect switch.Exhaust Fan Interlock – A relay installed in the unit control panel is energized when the blower is energized to interlock the unit with building exhaust fan(s).Power Through the Curb – A chase is installed in the curb, directly under the electrical control section to bring power wiring inside the curb, preventing a separate roof penetration. The sleeve must be sealed after wiring is completed with suit-able mastic to prevent water from entering the space.
Wiring Diagrams
Firestat – This control, mounted in the return air section, de-energizes the unit when return air reaches 135°F. The firestat is a manual reset control.Sure-Trip™ – This control automatically stops the unit whenever a phase is lost, when phases are out of sequence, or when supply voltage drops too low. Restart is automatic with a 5-minute delay after proper power supply conditions are restoredUnit Controller – A multi-function PLC controller is installed, in which complete unit operation is established through inputs of temperature, pressure, humidity sensors as well as other analog and digital inputs. The controller will provide a complete operating and monitoring system.
Wiring DiagramsThe wiring diagrams on the following pages are typical of those furnished with each unit, mounted on the inside of the unit control panel. For wiring diagrams of specific units not covered by these typical diagrams, consult our engineering department.
IM 1056 / Page 15 of 24
Wiring DiagramsFigure 14: Standard Recirculation Wall Thermostat, 208-230-460/60/3, Unit Sizes 096-300Note: See Figure 18 on page 19 for wire sizes
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Figure 15: Standard Recirculation Wall Thermostat, 208-230-460/60/3, Unit Sizes 096-300
Wiring Diagrams
IM 1056 / Page 17 of 24
Wiring Diagrams
Figure 16: Wiring Diagram Legend
Page 18 of 24 / IM 1056
Wiring Diagrams
Figure 17: Wiring Diagram Legend – Items Inside & Outside Control Panels
IM 1056 / Page 19 of 24
Figure 18: General Wiring Diagram Information
Wiring Diagrams
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Figure 19: Compressor Control Module Functional Operation
Wiring Diagrams
IM 1056 / Page 21 of 24
General Service Guide
Maintenance ProceduresProper, regularly scheduled maintenance is important to insure the most efficient operation and longest life for your equipment. The following points are to serve as a general guide. Always consult with your maintenance contractor with regard to the specific requirements of your own installation.a. Filters – Check the air filters at least once each month.
Wash or replace as required.b. Bearings – Only sealed bearings are used in the
evaporator blower motors. Therefore, bearing oiling is not required.
c. Paint Finish – Unit is primed and painted giving a durable finish. If paint lifting or peeling occurs, scrape and sand the affected area and touch up with paint obtained from the factory for this purpose.
d. Water system – The pump should be checked whenever filters are cleaned, to assure that it is operating normally. Clogged coils lead to high pressures and inefficient operation. Abnormal pressures may indicate liming or scaling. If so cleaning is necessary. Condenser coils should be checked yearly for liming or clogging.
e. Refrigerant Pressure – Check at any time unit does not seem to be performing at top efficiency. These should be checked only by a competent service contractor.
f. Contractor Points – Check contactor points twice a year, to be sure they are not badly burned or pitted as a result of low voltage, lightning strikes, or other electrical difficulties.
g. Condensate Drains – Always check to see that condensate is draining properly from the unit, whenever you check the filters.
h. Evaporator Fans – Be alert for any noise that would indicate blower wheels loose, motors or bearing failing.
i. Condensate Drain Pan – Each 6 months, clean and flush evaporator condensate drain pan.
j. Belts and Pulleys – Check whenever filters are changed, to make sure belts are tight and pulleys are not loose.
Trouble DiagnosisA. Symptom: Compressor will not run – no hum. Possible Causes: 1. Disconnect switch open. 2. Blown fuse(s). 3. Thermostat not calling. 4. Open control contacts – defective control. 5. High or low pressure control open or defective. 6. Oil pressure control open or defective (larger units
with semi-hermetic compressors). 7. Overload protector tripped or defective. 8. Defective wiring.
B. Symptom: Compressor will not start – hums but cycles on overload.
Possible Causes: 1. Low voltage. 2. Wiring incorrect or loose connections. 3. Blown fuse. 4. Compressor motor defective. 5. Bearings or pistons tight – low oil charge. 6. Defective compressor motor controller.C. Symptom: Compressor starts and runs but cycles on
overload protector. Possible Causes: 1. Low voltage. 2. Defective overload protector. 3. Defective high pressure control or lock-out circuit. 4. Compressor motor partially grounded. 5. Bearings or pistons tight – low oil pressure. 6. Improper refrigerant charge.D. Symptom: Head pressure too high. Possible Causes: 1. Refrigerant overcharge. 2. Air or other non-condensable gases in system. 3. Dirty or clogged condenser (cool cycle). 4. Defective fan motor (heat cycle). 5. Restriction in strainer or drier. 6. Restriction in discharge or liquid line. 7. Clogged air filter in unit (heat cycle). 8. Insufficient water flow (cool cycle). 9. Loose blowers, pulleys or belts (heat cycle). 10. Restricted air flow (heat cycle). 11. Defective expansion valve. 12 Indoor blower(s) running backwards (heat cycle).E. Symptom: Head pressure too low. Possible Causes: 1. Insufficient refrigerant charge. 2. Refrigerant leak in system. 3. Defective compressor. 4. Insufficient water flow (heat cycle). 5. Dirty or clogged water coil (heat cycle). 6. Leaking check valves. 7. Clogged air filter in unit (cool cycle). 8. Defective or improperly adjusted expansion valve. 9. Defective reversing valve.
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I. Symptom: Running cycle too long or unit operates continuously. Possible Causes: 1. Refrigerant undercharge – possible leak. 2. Dirty or restricted air coil (cool cycle) 3. Scaled or otherwise clogged water coil (heat cycle). 4. Control contacts stuck. 5. Air or other non-condensable gasses in system. 6. Restriction in suction or liquid line. 7. Unit too small for application. 8. Defective compressor. 9. Insufficient water flow (heat cycle) or insufficient
airflow (cool cycle). 10. Room thermostat malfunction or improper location. Incorrect heat anticipator setting.J. Symptom: Supply air temperature too low. Possible Causes: 1. Shortage of refrigerant or leak in system (cool cycle). 2. Restriction in strainer or drier (cool cycle). 3. Coil plugged with ice or dirt. 4. Defective compressor. 5. Restricted airflow (heat cycle). 6. Restricted water flow (cool cycle). 7. Maladjusted or defective expansion valve causing
high suction superheat and low suction pressure (cool cycle).
8. Defective reversing valve (cool cycle).K. Symptom: Supply air temperature too low. Possible Causes: 1. Compressor not running (heat cycle). 2. Refrigerant undercharge (heat cycle). 3. Insufficient water flow or temperature (heat cycle). 4. Malfunctioning or defective expansion valve (heat
cycle). 5. Defective (or stuck) reversing valve (heat cycle). 6. Insufficient airflow (cool cycle). 7. Dirty air filters (cool cycle). 8. Return air temperature too low.
General Service Guide
F. Symptom: Suction pressure too high. Possible Causes: 1. Refrigerant overcharge. 2. Defective compressor discharge valves. 3. Leaking check valve. 4. Defective expansion valve. 5. Expansion valve bulb not secured to suction line. 6. System overload – too much air or excessive temperatures (cool cycle) – too much water or excessive temperatures (heat cycle). 7. Defective reversing valve.G. Symptom: Suction pressure too low. Possible Causes: 1. Refrigerant undercharge. 2. Restriction in suction or liquid line. 3. Defective or improperly adjusted expansion valve. 4. Check valve not fully opening. 5. System underload – too little air or low entering temperature (cool cycle) – too little water or low entering temperature (heat cycle). 6. Clogged air filter in unit (cool cycle). 7. Loose blower(s), pulley(s) or belts (cool cycle). 8. Blower(s) running backwards (cool cycle).H. Symptom: Compressor short cycles. Possible Causes: 1. Room thermostat malfunction or improper location. Improper heat anticipator setting. 2. Refrigerant undercharge or overcharge and defective high or low pressure control or lockout
circuit. 3. Cycling on overload protector due to tight
bearings,stuck piston, high head pressure, or leaking discharge valves.
4. Defective expansion valve. 5. Insufficient water flow (both cycles). 6. Defective reversing valve. 7. Poor air distribution causing short circuiting.
IM 1056 / Page 23 of 24
L. Symptom: Noisy unit. Possible Causes: 1. Defective compressor. 2. Blower(s) out of balance. 3. Fan motor bearings worn. 4. Tubing rattle. 5. Loose parts (belts, pulleys, etc.) 6. Air velocity too high.M. Symptom: Liquid line too hot. Possible Causes: 1. Refrigerant undercharge or leak in system. 2. Excessive head pressure.N. Symptom: Liquid line frosted. Possible Causes: 1. Restriction upstream of point of frosting.
O. Symptom: Suction line frosted. Possible Causes: 1. Malfunctioning or defective expansion valve. 2. Refrigerant undercharge. 3. Restriction in suction or liquid line. 4. Insufficient evaporator air flow or temperature (cool
cycle). 5. Insufficient water flow or temperature (heat cycle).P. Symptom: Blower motor not running. Possible Causes: 1. Improper wiring. 2. Defective motor or controller. 3. Defective thermostat or control circuit. 4. Motor off on overload protective device.
General Service Guide
©2011 McQuay International • 800.432.1342 • www.mcquay.com IM 1056 / Page 24 of 24 / (7-11)
®
Warranty
All McQuay equipment is sold pursuant to its standard terms and conditions of sale, including Lim-ited Product Warranty. Consult your local McQuay Representative for warranty details. Refer to Form 933-43285Y. To find your local McQuay Representative, go to www.mcquay.com.
This document contains the most current product information as of this printing. For the most up-to-date product information, please go to www.mcquay.com.
Products Manufactured in an ISO Certified Facility.
McQuay Training and Development
Now that you have made an investment in modern, efficient McQuay equipment, its care should be a high priority. For training information on all McQuay HVAC products, please visit us at www.mcquay.com and click on training, or call 540-248-9646 and ask for the Training Department.
