McQuay WHR 100FA Installation Manual
Installation, Operation and Maintenance Manual IOMM WHR
Group: Chiller
Part Number: 330227701
Effective: June 2001
Supercedes: IM 224-5
Reciprocating Chillers
WHR 100FW to WHR 180FW, Packaged Water-Cooled
WHR 100FA to WHR 180FA, Remote Condenser
100 to 180 Tons, 350 to 630 kW
R-22, R134a
60 Hz
Table of Contents
Our facility is ISO Certified
Introduction..............................................3
General Description.................................................3
Nomenclature............................................................3
Inspection.................................................................3
Installation...............................................4
Handling....................................................................4
Moving the Unit.......................................................4
Location.....................................................................5
Space Requirements for Connections and
Servicing................................................................5
Placing the Unit........................................................5
Vibration Isolators....................................................6
Water Piping.............................................8
General.......................................................................8
Chilled Water Piping................................................9
Chilled Water Thermostat.....................................10
Flow Switch.............................................................10
Glycol Solutions.....................................................11
Condenser Water Piping.......................................12
Head Pressure Control, Tower System...............13
Head Pressure Control, Well Water System .......13
Water Pressure Drop.............................................14
Refrigerant Piping .................................16
Unit with Remote Condenser...............................16
Unit with Factory Mounted Condensers ...........19
Dimensional Data..................................20
Physical Data.........................................24
FW Water-Cooled..................................................24
FA Remote Condenser..........................................26
Wiring.....................................................29
Sequence of Operation..........................31
Electrical Data.......................................33
Control Center Layout, WHR 100F through
WHR 180F............................................................37
Start-Up and Shutdown..........................39
Pre Start-up.............................................................39
Start-up ....................................................................39
Weekend or Temporary Shutdown......................40
Start-up after Temporary Shutdown....................40
Extended Shutdown...............................................40
Start-up after Extended Shutdown.......................41
System Maintenance ............................42
General.....................................................................42
Control Center Service...........................................42
Electrical Terminals.................................................43
Operating Limits .....................................................43
Compressor Oil Level .............................................43
Oil Equalization.......................................................44
Refrigerant Sightglass and Moisture Indicator.44
Lead-Lag..................................................................44
Crankcase Heaters..................................................44
System Service......................................45
Filter-Driers..............................................................45
Liquid Line Solenoid Valve...................................45
Thermostatic Expansion Valve.............................46
Evaporator...............................................................47
Water Cooled Condenser......................................47
Standard Controls .................................48
Thermostat..............................................................48
Control Band...........................................................48
Oil Pressure Protection Control ............................49
Compressor Lockout..............................................50
High Pressure Control...........................................50
Low Pressure Control............................................51
Freezestat.................................................................51
Compressor Motor Protector ................................51
Optional Controls..................................52
Part Winding Start..................................................52
Low Ambient Start Timer (optional)....................52
Phase/Voltage Monitor (Optional).......................53
Alarm Bell (Optional).............................................53
High Return Water Control (Optional)................53
Hot Gas Bypass (Optional)...................................54
Controls, Settings and Functions..........55
Troubleshooting Chart ..........................57
2 WHR 100F through 180F IOMM WHR
"McQuay" is a registered trademark of McQuay International
"Illustrations and data cover McQuay International products at the time of publication and we reserve the right
to make changes in design and construction at anytime without notice".
2001 McQuay International
Introduction
General Description
McQuay Type WHR water chillers are designed for indoor installations and are compatible with either
air or water as a condensing medium. Each unit is completely assembled and factory wired before
evacuation, charging and testing. Each unit consists of accessible hermetic compressor(s),
replaceable tube shell-and-tube evaporator, water-cooled condenser (Model FW only), and complete
or partial refrigerant piping depending on the condensing medium.
Liquid line components that are included are manual liquid line shutoff valves, charging valves, filterdriers, liquid line solenoid valves, sightglass/moisture indicators, and balance port type thermal
expansion valves. Other features include compressor crankcase heaters, limited pumpdown during
“on” or “off” seasons, compressor lead-lag switch to alternate the compressor starting sequence, and
sequenced starting of compressors.
The electrical control center includes all equipment protection and operating controls necessary for
dependable automatic operation.
Compressor(s) are not fused, but can be protected by optional circuit breakers, or can rely on the field
installed fused disconnect for protection.
Nomenclature
W H R 100 - F W
Water Cooled
Condensing
Hermetic
Reciprocating
Nominal Capacity (Tons) Design Vintage
W = Single Water Cooled
Condenser per Refrigerant
Circuit
A = Unit Less Condensers
Inspection
When the equipment is received, all items should be carefully checked against the bill of lading to
provide a complete shipment. All units must be carefully inspected for damage upon arrival. All
shipping damage must be reported to the carrier and a claim must be filed with the carrier. The unit
serial plate should be checked before unloading the unit to be sure that it agrees with the power
supply available. Physical damage to unit after acceptance is not the responsibility of McQuay.
Note: Unit shipping and operating weights are given in the physical data tables beginning on
page 24.
IOMM WHR WHR 100F through 180F 3
Installation
Note: Installation and maintenance are to be performed only by qualified personnel who are
familiar with local codes and regulations, and experienced with this type of equipment.
CAUTION
Avoid contact with sharp edges. Personal injury can result.
Handling
Every model WHR water chiller with water-cooled condensers is shipped with a full refrigerant charge
For shipment the charge is contained in the condenser and is isolated by the manual condenser liquid
valve and the compressor discharge service valve.
A holding charge is supplied in remote condenser models. The operating charge must be field
supplied and charged.
If the unit has been damaged, allowing the refrigerant to escape, there can be danger of suffocation in
the equipment area since the refrigerant will displace the air. Be sure to review Environmental
Protection Agency (EPA) requirements if damage has occurred. Avoid exposing an open flame to the
refrigerant.
Moving the Unit
The McQuay water chiller is mounted on heavy wooden skids to protect the unit from accidental
damage and to permit easy handling and moving.
Figure 1, Moving the Unit
It is recommended that all moving and handling be
performed with the skids under the unit when
possible and that the skids not be removed until the
unit is in the final location. When moving the unit,
dollies or simple rollers can be used under the skids.
Never put the weight of the unit against the control
box.
In moving, always apply pressure to the base on the
skids only and not to the piping or shells. A long bar
will help move the unit easily. Avoid dropping the
unit at the end of the roll.
If the unit must be hoisted, it is necessary to lift the
unit by attaching cables or chains at the lifting holes
in the evaporator tube sheets. Spreader bars must be
used to protect the control cabinet and other areas of
the chiller (see Figure 1).
Do not attach slings to piping or equipment. Move unit in the upright horizontal position at all times.
Set unit down gently when lowering from the trucks or rollers.
Note: There will be extension brackets attached to the evaporator tube sheets on units
ordered with the optional acoustical enclosure. These brackets will be used for hoisting the
unit and should be removed when unit is in place.
4 WHR 100F through 180F IOMM WHR
Location
Unit is designed for indoor application and must be located in an area where the surrounding ambient
temperatures are 40°F (4°C) above. A good rule of thumb is to place units where ambient
temperatures are at least 5°F (3°C) above the leaving water temperature.
Because of the electrical control devices, the units should not be exposed to the weather. A plastic
cover over the control box is supplied as temporary protection during shipment. A reasonably level
and sufficiently strong floor is all that is required for the water chiller. If necessary, additional
structural members should be provided to transfer the weight of the unit to the nearest beams.
Note: Unit shipping and operating weights are available in the physical data tables beginning
on page 24.
Space Requirements for Connections and Servicing
The chilled water piping for all units enters and leaves the cooler from the rear, with the control box
side being the front side of the unit. A clearance of 3 to 4 feet (914 to 1219mm) should be provided for
this piping and for replacing the filter-driers, for servicing the solenoid valves, or for changing the
compressors, if it ever becomes necessary.
Figure 2, Clearance Requirements
The condenser water piping enters and
leaves the shell from the one end. Work
space must be provided for water
regulating valves and for general
servicing. Clearance should be
provided for cleaning condenser tubes
or for removing cooler tubes on one end
of the unit as specified in Table 1. It is
also necessary to leave a work area on
the end opposite that used for
replacement of a cooler tube. The "A"
dimension is to allow for control panel
door opening.
Table 1, Minimum Recommended Clearance Requirements
WHR 100F through 180F
In. (mm)
A B* C D*
46 (1168) 120 (3048) 36 (914) 120 (3048)
Placing the Unit
The small amount of vibration normally encountered with the water chiller makes this unit particularly
desirable for basement or ground floor installations where the unit can be bolted directly to the floor.
The floor construction should be such that the unit will not affect the building structure, or transmit
noise and vibration into the structure.
See vibration isolator for additional mounting information.
Note: The shipping bolts are used to secure the compressor rails to the evaporator brackets.
Remove these and discard after unit is mounted before unit is started.
IOMM WHR WHR 100F through 180F 5
Vibration Isolators
It is recommended that isolators be used on all upper level installations or areas in which vibration
transmission is a consideration.
Figure 3, Isolator Locations
Transfer the unit as indicated
under “Moving the Unit.” In all
cases, set the unit in place and
level with a spirit level. When
spring type isolators are
required, install springs running
under the main unit supports.
Adjust spring type mountings
so that upper housing clears
lower housing by at least ¼”
(6mm) and not more than ½” (13mm). A rubber anti-skid pad should be used under isolators if holddown bolts are not used.
Vibration eliminators in all water piping connected to the water chiller are recommended to avoid
straining the piping and transmitting vibration and noise.
Table 2, Weights & Mountings
Unit
Size
WHR100F
WHR110F
WHR120F
WHR135F
WHR150F
WHR165F
WHR180F
WHR100F
WHR110F
WHR120F
WHR135F
WHR150F
WHR165F
WHR180F
Opr.
Wt.
Lbs
(kg)
6170
(2799)
6340
(2876)
6480
(2939)
7195
(3264)
9195
(4171)
9290
(4214)
9300
(4218)
4705
(2134)
4730
(2146)
5245
(2379)
5440
(2468)
6080
(2754)
6500
(2944)
6900
(3130)
Corner Weight Lbs (kg) Neoprene-In-Shear Mountings Spring-Flex Mountings
1 2 3 4 1 2 3 4 1 2 3 4
ARRANGEMENT W – WHR WITH WATER COOLED CONDENSERS
1473
1386
1605
1706
(668)
(629)
(728)
1513
1424
1650
(686)
(646)
(749)
1530
1453
1703
(694)
(659)
(773)
1665
1634
1929
(755)
(741)
(875)
2171
2201
2362
(985)
(999)
(1072)
(1117)
2191
2227
2388
(994)
(1010)
(1083)
(1127)
2195
2225
2390
(996)
(1009)
(1084)
(1130)
ARRANGEMENT A – WHR WITHOUT WATER-COOLED CONDENSERS
1082
1035
1270
(491)
(470)
(576)
1088
1041
1277
(494)
(472)
(579)
1206
1154
1416
(547)
(524)
(642)
1251
1197
1469
(568)
(543)
(666)
1399
1337
1641
(634)
(606)
(743)
1495
1431
1756
(677)
(648)
(795)
1535
1565
1870
(696)
(710)
(848)
4-Red 4-Red 4-Red 4-Red CP2-32 CP2-32 CP2-32 CP2-32
(774)
1753
4-Red 4-Red 4-Red 4-Red CP2-32 CP2-32 CP2-32 CP2-32
(795)
1794
4-Red 4-Red 4-Red 4-Red CP2-32 CP2-32 CP2-32 CP2-32
(814)
1967
4-Green4-Green
(892)
2461
4-Gray 4-Gray 4-Gray 4-Gray CP4-31 CP4-31 CP4-31 CP4-31
2484
4-Gray 4-Gray 4-Gray 4-Gray CP4-31 CP4-31 CP4-31 CP4-31
2490
4-Gray 4-Gray 4-Gray 4-Gray CP4-31 CP4-31 CP4-31 CP4-31
1318
4-Red 4-Red 4-Red 4-Red CP2-31 CP2-31 CP2-31 CP2-31
(598)
1324
4-Red 4-Red 4-Red 4-Red CP2-31 CP2-31 CP2-31 CP2-31
(601)
1469
4-Red 4-Red 4-Red 4-Red CP2-31 CP2-31 CP2-31 CP2-31
(666)
1523
4-Red 4-Red 4-Red 4-Red CP2-32 CP2-32 CP2-32 CP2-32
(691)
1703
4-Red 4-Red 4-Red 4-Red CP2-32 CP2-32 CP2-32 CP2-32
(771)
1820
4-Green4-Green
(824)
1930
4-Green4-Green
(876)
4-
4-Green CP4-27 CP4-27 CP4-27 CP4-27
Green
4-
4-Green CP4-28 CP4-28 CP4-28 CP4-28
Green
4-
4-Green CP4-28 CP4-28 CP4-28 CP4-28
Green
6 WHR 100F through 180F IOMM WHR
Table 3, Spring Flex Isolators
Dimensions
In. (mm)
2¾
(70)
2¾
(70)
5
(127)
5
(127)
5
(127)
5
(127)
5
(149)
5
(149)
6
(156)
6
(156)
6
(156)
6
(156)
Part Number
886-477929A-31
886-477929A-32
886-580513A-27
886-580513A-28
886-580513A-31
886-580513A-32
Type Color
CP-2-31 Gray
CP-2-32 White
CP-4-27 Orange
CP-4-28 Green
CP-4-31 Gray
CP-4-32 White
Max.
Load
Each
Lbs. (kg)
2200
(998)
2600
(1180)
3000
(1361)
3600
(1633)
4400
(1996)
5200
(2359)
Defl.
In. (mm)
0.83
(21)
0.70
(17.8)
1.10
(27.9)
1.00
(25.4)
0.80
(20.3)
0.70
(17.8)
A B C D E
10¼
(260)9¼(235)8(203)
10¼
(260)9¼(235)8(203)
10¼
(260)9¼(235)7½(191)
10¼
(260)9¼(235)7½(191)
10¼
(260)9¼(235)7½(191)
10¼
(260)9¼(235)7½(191)
Table 4, Neoprene-in-Shear Isolators
Dimensions
In. (mm)
9
⁄16
(14.3)
(14.3)
(6.4)1¾(44.4)5½(165)3(85.7)
9
⁄16
(6.4)1¾(44.4)5½(165)3(85.7)
¼
¼
Type
Max. Load
Each
Lbs. (kg)
Defl.
In.
(mm)
A B C D E H L W
Black 250 (113) 216397A-04
Red 525 (238) 216397A-01
RP-3
Green 750 (340) 216397A-03
0.25
(6.4)2½(63.5)½(12.7)4(104.8)
Gray 1100 (499)
Black 1500 (681) 216398A-04
Red 2250 (1021) 216398A-01
RP-4
Green 3300 (1497) 216398A-03
0.25
(6.4)3¾(95.3)(15.9)5(14.3)
Gray 4000 (1815)
McQuay
McQuay
Part Number
216397A-05
216398A-05
Figure 4, Spring Flex Mountings Figure 5, Single Neoprene-in-Shear
Mounting
IOMM WHR WHR 100F through 180F 7
Water Piping
General
Due to the variety of piping practices, it is advisable to follow the recommendations of local
authorities. They can supply the installer with the proper building and safety codes required for a
safe and proper installation.
Basically, the piping should be designed with a minimum number of bends and changes in elevation to
keep system cost down and performance up. It should contain:
1. All piping should be installed and supported to prevent the unit connections from bearing any
2. Vibration eliminators to reduce vibration and noise transmission to the building.
3. Shutoff valves to isolate the unit from the piping system during unit servicing.
4. Manual or automatic air vent valves at the high points of the system. Drains should be placed at
5. Some means of maintaining adequate system water pressure (e.g., expansion tank or regulating
6. Temperature and pressure indicators located within 3 feet (0.9 meters) of the inlet and outlet of the
7. A strainer or some means of removing foreign matter from the water before it enters the pump is
8. A cleanable strainer should also be placed in the water lines just prior to the inlets of the
9. Any water piping to the unit must be protected to prevent freezing. Consult the ASHRAE
10. If the unit is used as a replacement chiller on a previously existing piping system, the system
11. The total quantity of water in the system should be sufficient to prevent frequent “on-off”
12. In the event glycol is added to the water system, as an afterthought for freeze protection,
13. A preliminary leak check of the water piping should be made before filling the system.
14. Many installations can realize considerable energy savings by reducing the chilled water flow
strain or weight of the system piping.
the lowest points in the system.
valve).
vessels to aid in unit servicing.
recommended. 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 prolong pump life
and thus keep system performance up.
evaporator and condenser. This will aid in preventing foreign material from entering and
decreasing the performance of the evaporator and condenser.
handbook for standard industry practice.
should be thoroughly flushed prior to unit installation and then regular water analysis and
chemical water treatment on the evaporator and condenser is recommended immediately at
equipment start-up.
cycling. The total quantity of water, in the system, turnover rate should not be less than 7
minutes.
recognize that the refrigerant suction pressure will be lower, cooling performance less, and water
side pressure drop is greater. If the percentage of glycol is large, or if propylene is employed
instead of ethylene glycol, the added pressure drop and loss of performance could be substantial.
Reset the freezestat and low leaving water alarm temperatures. The freezestat is factory set to
default at 36°F (2.2°C). Reset the freezestat setting to approximately 4° to 5°F (2.3° to 2.8°C)
below the leaving chilled water setpoint temperature. See the section titled “Glycol Solutions” for
additional information concerning glycol.
proportional to load and thereby reducing pump power input. Variable flow systems are
approved for WHR units provided
• The minimum flow does not go below the value shown in Table 6.
• The rate of flow change does not exceed 10 percent per minute.
8 WHR 100F through 180F IOMM WHR
Note: A water flow switch or pressure differential switch must be mounted in the evaporator
water lines to signal that there is water flow before the unit will start.
Figure 6, Typical Field Evaporator Water Piping
Note: Chilled water piping should be insulated.
Chilled Water Piping
The system water piping must be flushed thoroughly prior to making connections to the unit
evaporator. It is recommended that a strainer of 40 mesh be installed in the return water line before the
inlet to the chiller. Lay out the water piping so the chilled water circulating pump discharges into the
evaporator inlet.
The return water line must be piped to the evaporator inlet connection and the supply water line must
be piped to the evaporator outlet connection. If the evaporator water is piped in the reverse direction,
which is not recommended, a substantial decrease in capacity and efficiency of the unit will be
experienced.
A flow switch must be installed in the horizontal piping of the supply (evaporator outlet) water line to
provide water flow before starting the unit.
Drain connections should be provided at all low points in the system to permit complete drainage of
the system. Air vents should be located at the high points in the system to purge air out of the
system. A vent connection, located on top of the evaporator vessel, permits the purging of air out of
the evaporator. Air purged from the water system prior to unit start-up provides adequate flow
through the vessel and prevents safety cutouts on the freeze protection. System pressures can be
maintained by using an expansion tank as a combination pressure relief and reducing valve.
Pressure gauges should be installed in the inlet and outlet water lines to the evaporator. Pressure
drop through the evaporator should be measured to calculate proper gpm (L/s) as specified in the
Physical Data section tables. Vibration eliminators are recommended in both the supply and return
water lines.
Chilled water piping should be insulated to reduce heat loss and prevent condensation. Complete
unit and system leak tests should be performed prior to insulating the water piping. Insulation with a
vapor barrier would be the recommended type of insulation. If the vessel is insulated, the vent and
drain connections must extend beyond the proposed insulation thickness for accessibility. Chillers
not run in the winter should have their water systems thoroughly drained to protect against freezing.
If the chiller operates year-round, or if the system is not drained for the winter, the chilled water piping
exposed to outdoor ambient should be protected against freezing by wrapping the lines with a heater
cable. Also, an adequate percentage of glycol should be added to the system to further protect the
system during low ambient periods.
IOMM WHR WHR 100F through 180F 9
Chilled Water Thermostat
The chilled water sensor is factory installed in the leaving water connection on the evaporator. Care
should be taken not to damage the sensor cable or leadwires when working around the unit. It is also
advisable to check the leadwire before running the unit to be sure that it is firmly anchored and not
rubbing on the frame or any other component. If the sensor is ever removed from the well for
servicing, care must be taken as not to wipe off the heat conducting compound supplied in the well.
Note: See page 48 for additional thermostat information.
CAUTION
The thermostat bulb should not be exposed to water temperatures above 125°F
(51.7°C) since this will damage the control.
Table 5, Models and Sensor Locations
Installation
Model Number
Johnson UNT 33n-1 IOM UNT33n X
MicroTech, Control Manual OM RCPMICRO X
Figure 7, Thermostat Well Installation
Manual Name
Sensor LocationVendor
Return Leaving
Flow Switch
A water flow switch must be mounted in either the entering or leaving water line to provide adequate
water flow and cooling load to the evaporator before the unit can start. This will safeguard against
slugging the compressors on start-up. It also serves to shut down the unit in the event that water
flow is interrupted to guard against evaporator freeze-up.
A flow switch is available from McQuay under ordering number 01750330. It is a “paddle” type switch
and adaptable to any pipe size from 1” (25mm) to 6” (152mm) nominal. Certain minimum flow rates are
required to close the switch and are listed in Table 6. Installation should be as shown in Figure 8.
Electrical connections in the unit control center should be made at terminal 18 and B14. The normally
open contacts of the flow switch should be wired between these two terminals. There is also a set of
normally closed contacts on the switch that could be used for an indicator light or an alarm to indicate
when a “no flow” condition exists.
10 WHR 100F through 180F IOMM WHR
1. Apply pipe sealing compound to only the threads of the switch and screw unit into D” x D” x 1
(25mm) reducing tee (see Figure 8). The flow arrow must be pointed in the correct direction.
2. Piping should provide a straight length before and after the flow switch of at least five times the
pipe diameter.
3. Trim flow switch paddle if needed to fit the pipe diameter. Make sure paddle does not hang up in
pipe.
CAUTION
Make sure the arrow on the side of the switch is pointed in the direction of flow. The
flow switch is designed to handle the control voltage and should be connected
according to the wiring diagram (see wiring diagram inside control box door).
Incorrect installation will cause improper operation and possible evaporator damage.
Table 6, Flow Switch Minimum Flow Rates
Nominal Pipe Size
Inches (mm)
4 (101.6) 39.70 (2.50)
5 (127.0) 58.70 (3.70)
6 (152.4) 79.20 (5.00)
Minimum Required Flow to
Activate Switch – GPM (l/s)
Figure 8, Flow Switch
Glycol Solutions
The system glycol capacity, glycol solution flow rate in gpm (lps), pressure drop through the cooler,
and system pressure drop can be calculated using the following formulas and table.
1. Capacity — Capacity is reduced from that with plain water. To find the reduced value multiply the
chiller’s water system capacity by the capacity correction factor C to find the chiller’s capacity in
the glycol system.
2. Gpm —To determine evaporator gpm (or ∆T) knowing ∆T (or gpm) and capacity:
GPMGlycol
24
=
For Metric Applications — To determine evaporator lps (or ∆T) knowing ∆T (or lps) and kW:
LpsGlycol
IOMM WHR WHR 100F through 180F 11
kW
=
18.4
CapacityGlycolx
T
∆
Tx
∆
( )
FromTablesGx
TablesfromGFlowx
3. Pressure Drop — To determine glycol pressure drop through the cooler, enter the water pressure
drop graph on page 14 at the water flow. Multiply the water pressure drop found there by P to
obtain corrected glycol pressure drop.
4. To determine glycol system kW, multiply the water system kW by factor K.
Test coolant with a clean, accurate glycol solution hydrometer (similar to that found in service
stations) to determine the freezing point. Obtain percent glycol from the freezing point table below. On
glycol applications the supplier normally recommends that a minimum of 25% solution by weight be
used for protection against corrosion.
Note: The effect of glycol in the condenser is negligible. As glycol increases in temperature,
its characteristics have a tendency to mirror those of water. Therefore, for selection purposes,
there is no derate in capacity for glycol in the condenser.
Table 7, Ethylene Glycol
Freezing PointPercent
Glycol
10 26 -3 0.991 0.996 1.013 1.070
20 18 -8 0.982 0.992 1.040 1.129
30 7 -14 0.972 0.986 1.074 1.181
40 -7 -22 0.961 0.976 1.121 1.263
50 -28 -33 0.946 0.966 1.178 1.308
°F °C
C (Capacity) K (Power) G (Flow)
P (Pressure
Drop)
Table 8, Propylene Glycol
Freezing PointPercent
Glycol
10 26 -3 0.987 0.992 1.010 1.068
20 19 -7 0.975 0.985 1.028 1.147
30 9 -13 0.962 0.978 1.050 1.248
40 -5 -21 0.946 0.971 1.078 1.366
50 -27 -33 0.929 0.965 1.116 1.481
°F °C
C (Capacity) K (Power) G (Flow)
P (Pressure
Drop)
CAUTION
Do not use an automotive grade antifreeze. Industrial grade glycols must be used.
Automotive antifreeze contains inhibitors which all cause plating on the copper tubes
within the chiller evaporator. The type and handling of glycol used must be
consistent with local codes.
Condenser Water Piping
Arrange the condenser water so the water enters the bottom connection of the condenser. The
condenser water will discharge the condenser from the top connection. Failing to arrange the
condenser water as stated above will negatively affect the capacity and efficiency.
Pressure gauges should be installed in the inlet and outlet water lines to the condenser. Pressure drop
through the condenser should be measured to calculate proper gpm (L/s) as specified on page 15.
Vibration eliminators are recommended in both the supply and return water lines.
Water cooled condensers can be piped for use with cooling towers, well water, or heat recovery
applications. Cooling tower applications should be made with consideration to freeze protection and
scaling problems. Contact the cooling tower manufacturer for equipment characteristics and
limitations for the specific application.
12 WHR 100F through 180F IOMM WHR
Head Pressure Control, Tower System
Some means of controlling operating head pressure must be provided. Fan cycling and/or modulating
discharge dampers on the cooling towers are often used as shown in Figure 10. A three-way bypass
valve around the tower as shown in Figure 9 is also very common. The minimum entering tower
condenser water temperature is 60°F (16°C). In Figure 10 the capacity of the cooling tower is
controlled through damper and/or fan modulation. These typical systems, depending on the specific
application, must maintain a constant minimum condensing pressure, regardless of temperature
conditions and must provide enough head pressure for proper thermal expansion valve operation.
Note also that both systems provide full water flow to the condenser.
Head Pressure Control, Well Water System
When using city or well water for condensing refrigerant, a direct acting water regulating valve should
be installed in the outlet piping of each condenser (see Figure 11). The condenser purge valve
provides a convenient pressure tap for the regulating valve. The valve can modulate in response to
head pressure. On shutdown it closes, preventing water from siphoning out of the condenser.
Siphoning causes condenser water side drying and accelerates fouling. Figure 11 illustrates the
recommendation of a loop at the outlet end when no valve is used.
Figure 9, Three-way Water Valve Figure 10, Fan Modulation
Cooling
Tower
Condenser
Cooling
Tower
Condenser
Figure 11, Well Water Cooling System
IOMM WHR WHR 100F through 180F 13
Water Pressure Drop
The vessel flow rates must fall between the minimum and maximum values shown on the appropriate
evaporator and condenser curves. Flow rates below the minimum values shown will result in laminar
flow that will reduce efficiency, cause erratic operation of the electronic expansion valve and could
cause low temperature cutoffs. On the other hand, flow rates exceeding the maximum values shown
can cause erosion on the evaporator water connections and tubes.
McQuay encourages a minimum glycol concentration of 25% be provided on all glycol applications.
Glycol concentrations below 25% have too little inhibitor content for long-term corrosion protection
of ferrous metals.
Measure the chilled water pressure drop through the evaporator at field installed pressure taps. It is
important not to include valves or strainers in these readings.
Figure 12, Evaporator Water Pressure Drop, WHR 100F through 180F
110-120
100
135
150-165-180
Flow Rates: Evaporator flow rates must be within the flow limits set by the pressure
drop curve for each unit.
14 WHR 100F through 180F IOMM WHR
Figure 13, Condenser Water Pressure Drop, WHR 100F through 180F
100-110
120-135
165-180
150
Flow Rates: Condenser flow rates must be within the flow limits set by the pressure drop curve for
each unit.
IOMM WHR WHR 100F through 180F 15
Refrigerant Piping
Unit with Remote Condenser
General
For remote condenser application such as an air cooled condenser, the chillers are shipped containing
a Refrigerant 22 holding charge. It is important that the unit be kept tightly closed until the remote
condenser is installed, piped to the unit and the high side evacuated.
Refrigerant piping, to and from the unit, should be sized and installed according to the latest ASHRAE
Handbook. It is important that the unit piping be properly supported with sound and vibration
isolation between tubing and hanger and that the discharge lines be looped at the condenser and
trapped at the compressor to prevent refrigerant and oil from draining into the compressor discharge
manifold. Looping the discharge line also provides greater line flexibility.
The discharge gas valves, liquid line solenoids, filter-driers, moisture indicators, and thermostatic
expansion valves are all provided as standard equipment with the water chiller.
A liquid line shutoff valve must be added in the field on remote condenser units (Arrangement A)
between the liquid line filter-drier and remote condenser.
After the equipment is properly installed, the unit can be charged with Refrigerant 22, then run at
design load conditions, adding charge until the liquid line sightglass is clear, with no bubbles flowing
to the expansion valve. Total operating charge will depend on the air-cooled condenser used. The
charge for water-cooled units is shown in Table 9 through Table 12.
Note: On the Arrangement A units (units with remote condensers), the installer is required to
record the refrigerant charge by stamping the total charge and the charge per circuit on the
serial plate in the appropriate blocks provided for this purpose.
Water chillers without condensers require field piping to a remote condenser of some type. The
design of refrigerant piping when using air-cooled condensers involves a number of considerations
not commonly associated with other types of condensing equipment. The following discussion is
intended for use as a general guide to sound, economical and trouble-free piping of air-cooled
condensers.
Discharge lines must be designed to handle oil properly and to protect the compressor from damage
that can result from condensing liquid refrigerant in the line during shutdown. Total friction loss for
discharge lines of 3 to 6 psig (20.7 to 41.4 kPa) is considered good design. Careful consideration must
be given for sizing each section of piping to insure that gas velocities are sufficient at all operating
conditions to carry oil. If the velocity in a vertical discharge riser is too low, considerable oil can
collect in the riser and the horizontal header, causing the compressor to lose its oil and result in
damage due to lack of lubrication. When the compressor load is increased, the oil that had collected
during reduced loads can be carried as a slug through the system and back to the compressor, where a
sudden increase of oil concentration can cause liquid slugging and damage to the compressor.
Any horizontal run of discharge piping should be pitched away from the compressor approximately
1/8 inch (6.4mm) per foot (meter) or more. This is necessary to move by gravity any oil lying in the
header. Oil pockets must be avoided as oil needed in the compressor would collect at such points and
the compressor crankcase can become starved.
It is recommended that any discharge lines coming into a horizontal discharge header rise above the
center line of the discharge header. This is necessary to prevent any oil or condensed liquid from
draining to the top heads when the compressor is not running.
It is important that the liquid reach the expansion valve with no presence of flash gas since this gas
will reduce the capacity of the valve. Because “flashing” can be caused by a pressure drop in the
16 WHR 100F through 180F IOMM WHR
liquid lines, the pressure losses due to friction and changes in static head should be kept to a
minimum.
A check valve must be installed in the liquid line in all applications where the ambient temperature can
get below the equipment room temperature. This prevents liquid migration to the condenser, helps
maintain a supply of refrigerant in the liquid line for initial start-up and keeps liquid line pressure high
enough on “off” cycle to keep the expansion valve closed.
On systems as described above, a relief valve or relief type check valve must be used in the liquid line
as shown in piping systems Figure 14 to relieve dangerous hydraulic pressures that could be created
as cool liquid refrigerant in the line between the check valve and expansion or shutoff valve warms up.
A relief device is also recommended in the hot gas piping at the condenser coil as shown in Figure 14
and Figure 15.
Typical Arrangements
Figure 14 illustrates a typical piping arrangement involving a remote air cooled condenser located at a
higher elevation than the compressor and receiver. This arrangement is commonly encountered when
the air-cooled condenser is on a roof and the compressor and receiver are on grade level or in a
basement equipment room.
In this case, the design of the discharge line is very critical. It must be properly sized for full load
condition and have sufficient gas velocity at reduced loads to carry oil up through the discharge line
and condenser coil.
Notice in all illustrations that the hot gas line is looped at the bottom and top of the vertical run. This
is done to prevent oil and condensed refrigerant from flowing back into the compressor and causing
damage. The highest point in the discharge line should always be above the highest point in the
condenser coil; it is advisable to include a purging vent at this point to release noncondensables from
the system.
The inverted loop shown at the top of the riser is not required as long as the horizontal run to the
condenser is sloped downward to the condenser
The optional receiver is desirable in cases when the condenser cannot hold the entire refrigerant
charge or when a back-flooding type of head pressure control is used. The receiver is usually
bypassed during normal operation (except for back-flooding designs). It is important that the
refrigerant pass through the subcooler just prior to going to the expansion valve so that maximum
subcooling is in effect.
Figure 15 illustrates another common application where the air-cooled condenser is located on
essentially the same level as the compressor and receiver. The discharge line piping in this case is not
too critical. The principal program encountered with this arrangement is that there is frequently
insufficient vertical distance to allow free drainage of liquid refrigerant from the condenser coil to the
receiver.
NOTE : The illustrations show only one refrigerant circuit for the sake of clarity. All WHR units will
have two refrigerant circuits going to the condenser.
IOMM WHR WHR 100F through 180F 17
Figure 14, Condenser Above Compressor and Receiver
Figure 15, Condenser and Compressor on Same Level
18 WHR 100F through 180F IOMM WHR
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