“Scroll” Water-Cooled Packaged Unit - McQuay

CMWCP - 2004
“Scroll” Water-Cooled
Packaged Unit
Models: MWCP 18 A
MWCP 30 A
MWCP 35 A
MWCP 55 A
MWCP 70 A
MWCP 75 A
MWCP 85 A
MWCP 95 A
MWCP 105 A
MWCP 115 A
MWCP 125 A
MWCP 130 A
MWCP 160 A
MWCP 200 A

Contents
Description ....................................................................................................................2
Specification ............................................................................................................. 3- 7
Performance Table ........................................................................................................ 8
Outlines and Dimensions ...................................................................................... 9 - 12
Installation ............................................................................................................ 13 - 14
Piping Connections ............................................................................................. 15 - 16
Duct Connections ....................................................................................................... 17
Operation .....................................................................................................................18
Electrical Data ............................................................................................................. 19
Electronic Controller .......................................................................................... 20 – 21
Wiring Diagrams ................................................................................................... 22 - 31
Fan Curve ............................................................................................................. 32 – 36
Maintenance................................................................................................................. 37
Trouble Shooting......................................................................................................... 38
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: Sharp edges and coil surfaces are a potential injury hazard. Avoid contact with them.
Warning: Moving machinery and electrical power hazards. May cause severe personal injury or death.
Disconnect and lock off power before servicing equipment.
"McQuay" is a registered trademark of McQuay International. All rights reserved throughout the world.
©2003 McQuay International
"Bulletin illustrations cover the general appearance of McQuay International products at the time of publication
and we reserve the right to make changes in design and construction at any time without notice."
Page 1

Description
The McQuay “SCROLL” MWCP water-cooled packaged units are designed for duct type air-conditioning
system in commercial and industrial application. An optional plenum is available for MWCP18A-MWCP70A,
for free standing applications. The MWCP water-cooled packaged unit has single or multiple hermetic
compressors with independent refrigerant circuits. Each refrigerant circuit consists of a high efficiency
condenser, a sealed strainer, and capillary tubes. Every McQuay MWCP unit has been leak tested,
evacuated and fully charged with refrigerant R22 at the factory.
High Efficiency Hermetic Compliant Scroll Compressor (MWCP18A~MWCP125A)
• Quiet operation.
• Unmatched reliability with 70% fewer moving parts than comparably sized reciprocating compressors.
• Greater capability at handling liquid and debris in the system.
• High efficiency performance.
Enhanced Copper Tubes Condenser (MWCP70A~200A)
Extra-high efficiency is attained by special designed shell-and-tube condenser with “T” groove copper tube
surfaces for superior refrigerant-water heat transfer.
Anti-Corrosion Unit Casing
Unit casing is constructed of electro-galvanized steel sheet. Casing surface is finished with epoxy polyester
powder coating. Therefore, units are suitable for both commercial and industrial application.
Whisper- Quiet Operation
Each unit is divided into separate compartments such that compressor noise is kept away from the supply air
stream. Internal insulation of 1/2 inch thick fiberglass and double blowers design (only for MWCP85A~200A)
further reduce noise level.
Quality Assurance
Each unit is leak-tested, evacuated, fully charged with refrigerant and run tested in McQuay’s ISO9001
certified factory.
Page 2

Specifications
Specifications for 50Hz
MODEL MWCP18A MWCP30A MWCP35A MWCP55A MWCP70A
TOTAL COOLING CAPACITY
kcal/h 14620 22360 30100 45580 60370
Btu/h 58100 88800 119600 181000 240000
W 17000 26000 35000 53000 70200
ELECTRICAL HEATER W 6000 9000 12000 21000 27000
TOTAL POWER INPUT
COOLING kW 4.34 (4.16) 7.1 ( 7.1) 9.7 (9) 14.29 (13.49) 19 (18)
HEATING kW 6.55 (6.37) 10.1 (10.1) 14.2 (13.5) 24 (23.4) 31 (30)
POWER SOURCE V/Ph/Hz 380-415V / 3 / 50Hz
CAPACITY STEPS % 0 - 100 0 - 100 0 - 100 0-33-67-100 0 - 50 - 100
REFRIGERANT
REFRIGERANT CHARGE kg 1.45 2.5 3.1 1.7 + 3.3 3.7 x 2
REFRIGERANT CONTROL
EVAPORATOR
FAN
AIR FLOW
TYPE
R22
CAPILLARY TUBES
ALUMINIUM SLIT FINS / COPPER TUBES
ROWS 3 3 3 3 3
FPI 12 12 12 13 13
TYPE
DRIVE
EXTERNAL STATIC PRESSURE
CONDENSER
DIMENSIONS
DOUBLE SUCTION MULTI-BLADE CENTRIFUGAL TYPE
BELT DRIVE
MOTOR OUTPUT kW 0.55 (0.37) 1.1 2.2 (1.5) 3 (2.2) 4 (3)
TYPE
m³/h 2880 4200 5400 8100 10800
CFM 1694 2470 3176 4765 6353
inWg 0.31 (0) 0.39 (0) 0.39 (0) 0.59 (0) 0.59 (0)
Pa 80 (0) 100 (0) 100 (0) 150 (0) 150 (0)
TUBE IN TUBE
WATER FLOW m³/h 3.4 5.5 8.5 11 12.6
WATER HEADLOSS mH 2 O 3.5 3.7 3.8 4 4.2
LENGTH mm 1078 1078 1278 1722 1922
WIDTH mm 647 647 677 736 836
HEIGHT mm 1789 (2058) 1789 (2058) 1902 (2172) 1921 (2195) 2035 (2404)
NET WEIGHT kg 205 (220) 235 (250) 280 (300) 455 (485) 610 (650)
AIR FILTER
COMPRESSOR
DIMENSION mm 825 × 565 825 × 754 1025 × 775 725 × 725 825 × 825
QUANTITY 1 1 1 2 2
TYPE
SCROLL
QUANTITY 1 1 1 2 2
POWER OUTPUT kW 3.79 6 7.5 3.79 + 7.5 7.5 × 2
SOUND PRESSURE LEVEL dB(A) 52 63 65 67 70
Note:
1. The nominal cooling capacity is based on the following condition: entering air temperature 26.7ºC (80ºF) db, 19.5ºC (67ºF) wb, entering cooling
water temperature 29.4ºC (85ºF), leaving cooling water temperature 35ºC (95ºF).
2. Capacities are gross capacities which do not include a deduction for evaporator fan motor heat.
3. External static pressures are maximum allowable ESP based on standard motors at nominal airflow.
4. Specifications are subject to change without prior notice.
5. The numbers in the parentheses are applicable for the units with plenum.
Page 3

MODEL MWCP75A MWCP85A MWCP95A MWCP105A MWCP115A
kcal/h 68270 74820 83580 91160 98900
TOTAL COOLING CAPACITY
Btu/h 270910 297400 331640 362400 393160
W 79400 97000 97200 106000 115000
ELECTRICAL HEATER W 36000 36000 42000 42000 48000
TOTAL POWER INPUT
COOLING kW 22 23.5 26.5 28 32.5
HEATING kW 40 40 47.5 47.5 53.5
POWER SOURCE V/Ph/Hz 380-415V / 3 / 50Hz
CAPACITY STEPS % 0 - 50 - 100 0 - 50 -100 0-46-54-100 0 - 50 - 100 0-33-67-100
REFRIGERANT
R22
REFRIGERANT CHARGE kg 4.3 x 2 4.1 x 2 7.1 + 5.7 5 x 2 4.4 x 3
REFRIGERANT CONTROL
CAPILLARY TUBES
TYPE
ALUMINIUM SLIT FINS / COPPER TUBES
EVAPORATOR
ROWS 2 2 3 3 4
FPI 12 12 12 12 12
TYPE
DOUBLE SUCTION MULTI-BLADE CENTRIFUGAL TYPE
FAN
DRIVE
BELT DRIVE
MOTOR OUTPUT kW 4 4 5.5 5.5 5.5
AIR FLOW
m³/h 13600 13600 16000 16000 19800
CFM 8000 8000 9412 9412 11647
inWg 0.79 0.79 0.98 0.98 0.98
EXTERNAL STATIC PRESSURE
Pa 200 200 250 250 250
TYPE
SHELL & TUBE
CONDENSER
WATER FLOW m³/h 13.8 15 18.7 20.6 23
WATER HEADLOSS mH 2 O 4.3 4.3 4.5 4.5 4.5
LENGTH mm 1962 1962 1962 1962 2182
DIMENSIONS
WIDTH mm 1060 1060 1060 1060 1243
HEIGHT mm 1961 1961 1961 1961 2040
NET WEIGHT kg 720 800 930 940 1010
DIMENSION mm 529 x 660 593 x 686
AIR FILTER
QUANTITY 6 6
TYPE
SCROLL RECIPROCATE
COMPRESSOR QUANTITY 2 2 2 2 3
POWER OUTPUT kW 9 x 2 9.75 x 2 11.25 + 9.75 11.25 x 2 9 x 3
SOUND PRESSURE LEVEL dB(A) 72 72 74 74 75
Note:
1. The nominal cooling capacity is based on the following condition: entering air temperature 26.7ºC (80ºF) db, 19.5ºC (67ºF) wb, entering cooling
water temperature 29.4ºC (85ºF), leaving cooling water temperature 35ºC (95ºF).
2. Capacities are gross capacities which do not include a deduction for evaporator fan motor heat.
3. External static pressures are maximum allowable ESP based on standard motors at nominal airflow.
4. Specifications are subject to change without prior notice.
5. The numbers in the parentheses are applicable for the units with plenum.
Page 4

MODEL MWCP125A MWCP130A MWCP160A MWCP200A
kcal/h 109540 112660 141040 171020
TOTAL COOLING CAPACITY
Btu/h 434690 447800 560680 678030
W 127400 131000 164000 198720
ELECTRICAL HEATER W 48000 48000 60000 60000
TOTAL POWER INPUT
COOLING kW 34.5 36.75 48 61
HEATING kW 55.5 55.5 71 84
POWER SOURCE V/Ph/Hz 380-415V / 3 / 50Hz
CAPACITY STEPS % 0-33-67-100 0-33-67-100 0 - 50 -100 0-20-40-60-80-100
REFRIGERANT
R22
REFRIGERANT CHARGE kg 4.5 x 3 5.8 x 3 7.4 x 2 (14 x 2) + 12
REFRIGERANT CONTROL
CAPILLARY TUBES
TYPE
ALUMINIUM SLIT FINS / COPPER TUBES
EVAPORATOR
ROWS 4 4 4 4
FPI 12 12 12 12
TYPE
DOUBLE SUCTION MULTI-BLADE CENTRIFUGAL TYPE
FAN
DRIVE
BELT DRIVE
MOTOR OUTPUT kW 7.5 7.5 11 7.5x2
AIR FLOW
m³/h 22000 22000 26400 31800
CFM 12941 12941 15529 530
EXTERNAL STATIC PRESSURE
inWg 1.18 1.18 1.18 1.38
Pa 300 300 300 350
TYPE
SHELL & TUBE
CONDENSER
WATER FLOW m³/h 25.4 26.3 31 4
WATER HEADLOSS mH 2 O 4.6 4.6 4.6 5.7
LENGTH mm 2182 2182 2182 3012
DIMENSIONS
WIDTH mm 1243 1243 1243 1534
HEIGHT mm 2040 2040 2040 2083
NET WEIGHT kg 1030 1150 1210 1400
AIR FILTER
DIMENSION mm 593 x 686 593 x 686 629 x 673
QUANTITY 6 6 8
TYPE
SCROLL RECIPROCATE
COMPRESSOR
QUANTITY 3 3 2 3
POWER OUTPUT kW 9 x 3 9.75 x 3 18.5 x 2 (18.5 x 2) + 9
SOUND PRESSURE LEVEL dB(A) 76 76 77 79
Note:
1. The nominal cooling capacity is based on the following condition: entering air temperature 26.7ºC (80ºF) db, 19.5ºC (67ºF) wb, entering cooling
water temperature 29.4ºC (85ºF), leaving cooling water temperature 35ºC (95ºF).
2. Capacities are gross capacities which do not include a deduction for evaporator fan motor heat.
3. External static pressures are maximum allowable ESP based on standard motors at nominal airflow.
4. Specifications are subject to change without prior notice.
5. The numbers in the parentheses are applicable for the units with plenum.
Page 5

Specifications For 60Hz
MODEL MWCP18A MWCP30A MWCP35A MWCP55A MWCP70A
TOTAL COOLING CAPACITY
kcal/h 14450 19780 27520 42140 55040
Btu/h 57320 78630 109400 167520 218800
W 16800 23000 32000 49000 64000
TOTAL POWER INPUT COOLING kW 4.09 (3.91) 6.14 8.95 (8.25) 13.11(12.31) 17.5 (16.5)
POWER SOURCE V/Ph/Hz 460V / 3 / 60Hz
CAPACITY STEPS % 0 - 100 0 - 100 0 - 100 0-33-67-100 0 - 50 - 100
REFRIGERANT
REFRIGERANT CHARGE kg 1.5 1.8 3 1.5 + 2.8 3.1 + 3.6
REFRIGERANT CONTROL
R22
CAPILLARY TUBES
EVAPORATOR TYPE ALUMINIUM SLIT FINS / COPPER TUBES
FAN
AIR FLOW
TYPE
DRIVE
EXTERNAL STATIC PRESSURE
CONDENSER
DIMENSIONS
DOUBLE SUCTION MULTI-BLADE CENTRIFUGAL TYPE
BELT DRIVE
MOTOR OUTPUT kW 0.55 (0.37) 1.1 2.2 (1.5) 3 (2.2) 4 (3)
m³/h 2880 4200 5400 8100 10800
CFM 1694 2470 3176 4765 6353
inWg 0.31 (0) 0.39 (0) 0.39 (0) 0.59 (0) 0.59 (0)
Pa 80 (0) 100 (0) 100 (0) 150 (0) 150 (0)
TYPE TUBE IN TUBE SHELL & TUBE
WATER FLOW m³/h 3.4 5.5 8.5 11 12.6
WATER HEADLOSS mH 2 O 3.5 3.7 3.8 4 4.2
LENGTH mm 1078 1078 1278 1722 1922
WIDTH mm 647 647 677 736 836
HEIGHT mm 1789 (2058) 1789 (2058) 1902 (2172) 1921 (2195) 2035 (2404)
NET WEIGHT kg 205 (220) 235 (250) 280 (300) 455 (485) 610 (650)
AIR FILTER
COMPRESSOR
DIMENSION mm 825 × 565 825 × 754 1025 × 775 725 × 725 825 × 825
QUANTITY 1 1 1 2 2
TYPE
SCROLL
QUANTITY 1 1 1 2 2
POWER OUTPUT kW 3.54 5.04 6.75 3.54 + 6.75 6.75 × 2
SOUND PRESSURE LEVEL dB(A) 52 63 65 67 70
Note:
1. The nominal cooling capacity is based on the following condition: entering air temperature 26.7ºC (80ºF) db, 19.5ºC (67ºF) wb, entering cooling
water temperature 29.4ºC (85ºF), leaving cooling water temperature 35ºC (95ºF).
2. Capacities are gross capacities which do not include a deduction for evaporator fan motor heat.
3. External static pressures are maximum allowable ESP based on standard motors at nominal airflow.
4. Specifications are subject to change without prior notice.
5. The numbers in the parentheses are applicable for the units with plenum.
Page 6

MODEL MWCP85A MWCP105A MWCP115A MWCP130A MWCP160A
kcal/h 68800 79120 92880 103200 130720
TOTAL COOLING CAPACITY
Btu/h 273500 314530 369230 410260 519660
W 80000 92000 108000 120000 152000
TOTAL POWER INPUT COOLING kW 22 25 28 34.5 41
POWER SOURCE V/Ph/Hz 460V / 3 / 60Hz
CAPACITY STEPS % 0 - 50 -100 0 - 50 - 100 0-33-67-100 0-33-67-100 0 - 50 -100
REFRIGERANT
R22
REFRIGERANT CHARGE kg 5.2 × 2 5.3 × 2 3.7 x 3 4.1 + 4.4 + 4.4 7.0 × 2
REFRIGERANT CONTROL
CAPILLARY TUBES
EVAPORATOR TYPE ALUMINIUM SLIT FINS / COPPER TUBES
TYPE
DOUBLE SUCTION MULTI-BLADE CENTRIFUGAL TYPE
FAN
DRIVE
BELT DRIVE
MOTOR OUTPUT kW 4 5.5 5.5 7.5 11
AIR FLOW
m³/h 13600 16000 19800 22000 26400
CFM 8000 9412 11647 12941 15529
EXTERNAL STATIC PRESSURE
inWg 0.79 0.98 0.98 1.18 1.18
Pa 200 250 250 300 300
TYPE
SHELL & TUBE
CONDENSER
WATER FLOW m³/h 15 20.6 23 26.3 31
WATER HEADLOSS mH 2 O 4.3 4.5 4.5 4.6 4.6
LENGTH mm 1962 1962 2182 2182 2182
DIMENSIONS
WIDTH mm 1060 1060 1243 1243 1243
HEIGHT mm 1961 1961 2040 2040 2040
NET WEIGHT kg 800 940 1010 1150 1210
AIR FILTER
DIMENSION mm 529 × 660 593 × 686
QUANTITY 6 6
TYPE
SCROLL RECIPROCATE
COMPRESSOR
QUANTITY 2 2 3 3 2
POWER OUTPUT kW 9 × 2 9.75 × 2 7.5 × 3 9 × 3 15 × 2
SOUND PRESSURE LEVEL dB(A) 72 74 75 76 77
Note:
1. The nominal cooling capacity is based on the following condition: entering air temperature 26.7ºC (80ºF) db, 19.5ºC (67ºF) wb, entering cooling
water temperature 29.4ºC (85ºF), leaving cooling water temperature 35ºC (95ºF).
2. Capacities are gross capacities which do not include a deduction for evaporator fan motor heat.
3. External static pressures are maximum allowable ESP based on standard motors at nominal airflow.
4. Specifications are subject to change without prior notice.
5. The numbers in the parentheses are applicable for the units with plenum.
Page 7

Performance Table
AIR ON EVAPORATOR
WATER TEMPERATURE OFF CONDENSER
21ºC 35ºC 40ºC
MODEL
NOMINAL AIR
FLOW m 3 /h
DB TEMP ºC
WB TEMP ºC
TOTAL
CAPACITY
(kW)
SENSIBLE
CAPACITY
(kW)
INPUT
(kW)
TOTAL
CAPACITY
(kW)
SENSIBLE
CAPACITY
(kW)
INPUT
(kW)
TOTAL
CAPACITY
(kW)
SENSIBLE
CAPACITY
(kW)
INPUT
(kW)
MWCP18A 2880
21 15 15.42 9.82 3.46 14.53 9.58 4.24 14.25 9.66 4.56
27 19 16.99 11.49 3.56 16.00 11.12 4.34 15.61 11.18 4.71
32 23 18.32 13.08 3.66 17.59 12.96 4.45 17.57 13.28 4.83
MWCP30A 4200
21 15 23.13 14.90 5.71 21.79 14.27 6.94 21.37 14.34 7.45
27 19 25.48 17.35 5.87 24.00 16.70 7.10 23.42 16.89 7.69
32 23 27.48 19.81 6.02 26.39 19.48 7.28 26.36 20.06 7.88
MWCP35A 5400
21 15 30.84 20.39 9.43 29.05 18.94 9.01 28.49 19.12 8.88
27 19 33.97 22.69 10.16 32.00 22.02 9.70 31.22 22.29 9.52
32 23 36.63 25.97 10.79 35.18 25.54 10.45 35.14 26.32 10.44
MWCP55A 8100
21 15 47.23 31.46 11.67 44.49 30.61 13.99 43.63 30.98 14.95
27 19 52.02 36.73 11.97 49.00 35.57 10.29 47.81 36.00 15.40
32 23 56.10 41.79 12.27 53.87 41.26 14.63 53.81 42.62 15.76
MWCP70A 10800
21 15 62.65 40.60 15.52 59.01 39.06 18.60 57.88 39.71 19.88
27 19 69.01 47.34 15.92 65.00 45.70 19.00 63.42 45.85 20.47
32 23 74.41 54.24 16.31 71.46 53.09 19.45 71.38 54.25 20.95
MWCP75A 13600
21 15 70.85 47.61 17.82 66.73 46.18 21.52 65.45 46.73 23.05
27 19 78.03 55.32 18.30 73.50 53.58 22.00 71.71 54.00 23.77
32 23 84.14 63.02 18.77 80.81 62.06 22.54 80.72 64.09 24.34
MWCP85A 13600
21 15 79.04 53.11 18.97 74.45 51.52 22.98 73.02 52.14 24.64
27 19 87.06 61.73 19.49 82.00 59.78 23.50 80.00 60.24 25.41
32 23 93.88 70.32 20.00 90.15 69.24 24.09 90.05 71.50 26.04
MWCP95A 16000
21 15 86.75 59.34 21.63 81.71 57.28 25.95 80.14 58.34 27.73
27 19 95.55 68.99 22.18 90.00 66.69 26.50 87.81 67.35 28.56
32 23 103.03 78.51 22.74 98.95 77.28 27.13 98.84 79.47 29.23
MWCP105A 16000
21 15 96.39 65.93 22.78 90.79 63.64 27.41 89.05 64.83 29.32
27 19 106.17 76.65 23.37 100.00 74.10 28.00 97.57 74.84 30.21
32 23 114.48 87.23 23.97 109.94 85.86 28.68 109.82 88.30 30.93
MWCP115A 19800
21 15 106.03 69.66 26.23 99.87 67.11 31.79 97.95 68.37 34.08
27 19 116.78 81.05 26.95 110.00 78.32 32.50 107.32 78.99 35.15
32 23 125.93 92.56 27.66 120.93 91.18 33.32 120.80 93.86 36.02
MWCP125A 22000
21 15 113.74 74.84 28.23 107.13 72.53 33.79 105.08 73.24 36.08
27 19 125.28 87.45 28.95 118.00 84.37 34.50 115.13 84.85 37.15
32 23 135.09 100.51 29.66 129.73 97.95 35.32 129.58 100.42 38.02
MWCP130A 22000
21 15 118.56 78.01 29.96 111.67 75.60 35.98 109.53 76.34 38.46
27 19 130.58 91.14 30.73 123.00 87.95 36.75 120.01 88.45 39.62
32 23 140.81 104.76 31.51 135.23 102.10 37.63 135.08 104.69 40.56
MWCP160A 26400
21 15 146.51 97.72 39.41 138.00 93.70 47.02 135.35 95.42 50.16
27 19 161.37 113.44 40.39 152.00 109.29 48.00 148.30 109.89 51.63
32 23 174.01 129.46 41.37 167.11 126.67 49.12 166.92 130.36 52.82
MWCP200A 31800
21 15 177.36 118.30 50.32 167.06 111.93 59.78 163.85 109.78 63.69
27 19 195.35 130.30 51.54 184.00 123.28 61.00 179.52 120.28 65.51
32 23 210.65 141.14 52.75 202.29 135.53 62.39 202.06 137.80 66.99
Note:
1. Cooling capacity based on Nominal Airflow Rate under given conditions.
2. Direct interpolation is permissible but extrapolation is not recommended.
3. Ratings are gross capacities. For net capacities, deduct evaporator blower motor heat.
4. The kW input ratings listed above are compressor kW.
Page 8

••••
••••
Outlines and Dimensions
MWCP18A/30A
PLENUM
CONDENSATE DRAI N 1"
INSTALLATION
CLEARANCES
1
WATER OUTLET 4"
WATER I NLET 1
4"
CABLE ENTRY 2"
EMERGENCY DRAIN 1"
FRONT: 900
REAR: 600
LEFT: 900
RIGHT: 900
Dimension in mm
MWCP35A
PLENUM
CONDENSATE DRAI N 1"
INSTALLATION
CABLE ENTRY 2" CLEARANCES
1 WATER I NLET 1/ 4 "
EMERGENCY DRAIN 1"
1
WATER OUTLET 1/ 4"
FRONT: 900
REAR: 600
LEFT: 900
RIGHT: 900
Dimension in mm
Page 9

••••
CABLE
••••
MWCP55A
PLENUM
WATER I NLET 2"
WATER OUTLET 2"
CONDENASATE RRAI N 1"
ENTER 2"
INSTALLATION
CLEARANCES
EMERGENCY DRAI N 1"
FRONT: 900
REAR: 600
LEFT: 900
RIGHT: 900
Dimension in mm
MWCP70A
PLENUM
CONDENSATE DRAI N 1"
INSTALLATION
CLEARANCES
WATER OUTLET 2"
WATER I NLET 2"
CABLE ENTER 2"
EMERGENCY DRAI N 1"
FRONT: 900
REAR: 600
LEFT: 900
RIGHT: 900
Dimension in mm
Page 10

TEMP UP TEMP DOWN
COOL
HEAT
MODE
••••
W- PUMP
FAN
COMP2
AUTO
COMP1
COMP3
COMP
RESET
ON/OFF
EG SAVER
TI ME
TEMP UP TEMP DOWN
COOL AUTO W-PUMP
HE AT COMP1 FAN
COMP2
COMP3
MODE
COMP
••••
RESET
ON/ OFF
EG SAVER
TI ME
MWCP75A/85A/95A105A
INSTALLATION
CLEARANCES
FRONT: 900
REAR: 1500
LEFT: 900
RIGHT: 900
MODEL
MWP25B/ 25A
MWP30B/ 30A
N ( DI MENSI ON)
2"
2- 1/ 2"
Dimension in mm
AI R FI LTER
COOLI NG COIL
WATER OUTLET N
EMERGENCY DRAI N 1"
WATER INLET N
CONDENSATE DRAI N 1"
CABLE ENTRY 2"
MWCP115A/125A/130A
INSTALLATION
CLEARANCES
FRONT: 900
REAR: 1500
LEFT: 900
RIGHT: 900
Dimension in mm
AI R FI LTER
COOLI NG COIL
CONDENSATE DRAIN 1"
WATER OUTLET 2 1/ " 2
WATER I NLET 2 1/ 2 "
EMERGENCY DRAI N 1"
CABLE ENTRY 2"
Page 11

MWCP160A
INSTALLATION
CLEARANCES
FRONT : 900
REAR : 1500
LEFT : 900
RIGHT : 900
Dimensions in mm
MWCP200A
INSTALLATION
CLEARANCES
FRONT : 900
REAR : 1500
LEFT : 900
RIGHT : 900
Dimensions in mm
Page 12

Installation
General
CAUTION
To protect warranty, this equipment must be installed and serviced by authorized McQuay service personnel or a qualified
service person experienced in air conditioning equipment installation. Installation must comply with all applicable codes,
particularly in regard to electrical wiring and other safety elements such as relief valves, HP cutout settings, design working
pressures and ventilation requirements consistent with the amount and type of refrigerant charge.
Inspection
As soon as the unit is received, it should be inspected for any damage that may have occurred in transit. If
damage is evident, it should be noted on the carrier’s freight bill. A separate request for inspection by the
carrier’s agent should be made in writing at once.
Concealed damage must be reported within 15 days of receipt of shipment. Check shipment against the bill
of lading to verify that all items were delivered. Any shortages should be noted on the delivery receipt, and a
claim filed immediately.
Limitations
1. An excessively high waterflow and a low water temperature may cause condensate to freeze on the
surface of the evaporator coil.
2. An excessively low waterflow and a high water temperature may cause the unit to shut down on its highpressure
cutout.
3. These units are not suitable for outdoor installation.
4. These units should be installed in accordance with:
a) Regulations of local utility or other authorities having jurisdiction.
b) Wiring must conform to provisions of local ordinances.
Handling
Each unit is skidded at the factory. Care should be used during handing to avoid damage to the unit and
components.
Normally, the unit can be moved into position using a lift truck or pipe roller and under no circumstances
should they be “walked” on the corners of the crate.
The skids should not be removed till the unit is set in position. If the unit must be lifted by a crane or hoist,
spreader bars and pads must be used to prevent damage. (See Table 1 for shipping weights.)
Location and Clearances
The packaged unit is designed for installation on a flat and level concrete foundation. It must be capable of
supporting the operating weight of the unit.
Table 1 –Shipping Weights
MODEL WEIGHT(kg) MODEL WEIGHT (kg)
MWCP18A 295 (315) MWCP95A 1095
MWCP30A 325 (345) MWCP105A 1105
MWCP35A 375 (400) MWCP115A 1200
MWCP55A 560 (600) MWCP125A 1220
MWCP70A 725 (780) MWCP130A 1340
MWCP75A 885 MWCP160A 1400
MWCP85A 965 MWCP200A 1590
NOTE: Make sure there is adequate clearances and floor strength through doors and passageways.
Page 13

The units are constructed of general purpose, indoor application and are not intended for wet, corrosive or
explosive atmospheres. ON INSTALLATIONS WHERE THE UNIT OR COOLING TOWER COULD BE
EXPOSED TO LOW AMBIENT CONDITIONS, FREEZE PROTECTION IS THE RESPONSIBILITY OF
OTHERS.
Installation should allow for water drain, ventilation and clearances for service, including removal of
compressor(s) and condenser. Recommended minimum clearances are shown on the unit dimensions
drawing (See page7~11.)
Acoustical Considerations
With any mechanical system, a certain amount of vibration and noise is generated. To insure a successful
installation of these units, McQuay has provided the following:
1. Internal vibration isolators for compressors.
2. Acoustically treated fan section (standard).
If return air duct is to be used, a flex connector must be field supplied.
Care must be exercised to isolate the unit and piping from walls and ceiling.
Besides vibration which is transmitted by conduction, radiated noise and fan noise must also be addressed.
Compressors, pumps etc., all generated noise can be radiated to the occupied space. The most common
approach to reducing this possibility is to locate the units in least sensitive areas. This could be near stairs,
elevators or lavatories.
Good acoustical practices should be employed when designing the walls between the machine room and the
occupied space. All openings around doors should be sealed. The return air opening must be acoustically
treated.
Noise will also be carried through the fan and supply ductwork to the occupied space. When the sound
attenuation package is required, you should consider installing sound attenuation in the supply ductwork.
Page 14

Piping Connections
General
All system piping should be installed in accordance with local code ordinances. The piping should be
designed with a minimum number of bends and changes in elevation to keep costs to a minimum and unit
performance to a maximum.
A good installation should include the following:
1. Vibration eliminators to reduce vibration and noise transmission to the building.
2. Shut-off valves to isolate the unit from the piping system during service.
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., regulating valve and/or expansion
tank).
5. Install temperature and pressure indicators at the unit to aid in servicing and trouble shooting.
6. Installation of a strainer to remove foreign matter from the water before it enters the pump. It should be
located far enough upstream of the pump to prevent cavitation at the inlet.
Consider Water Piping
All internal condenser water piping is completed factory assembled. Field piping should be connected to the
pipes that are stubbed out at the panels. Supply water must be connected to the factory piping as indicated
by the markings on the unit.
FIG.1-CONDENSER WATER PIPING COOLING TOWER
Water Cooling Tower Piping
When installing these units with a cooling tower, some means of controlling head pressure must be
provided.
Water flow through the cooling tower should be constant at the same time. It must be possible to vary the
water flow through the condenser to keep the condensing pressure and temperature constant according to
load and outside temperature and wet bulb conditions to assure proper operation of the thermal expansion
valve or valves. This may be accomplished by installing a 3-way water-regulating valve as shown in Fig.1.
The valve should be set to maintain 65ºC minimum leaving condenser water temperature.
The use of a three way water regulating valve with bypass is highly recommended since it maintains
constant condensing pressure regardless of outside temperature conditions and insures proper operation of
the evaporator expansion valve.
It is important to follow the instructions of the water regulating valve manufacturer in regard to installation
recommendations and valve adjustment procedures.
Thermometer wells should be located at the condenser inlet and outlet to and in performance and service
work.
Page 15

Condensate Drain
Two standard drain connections:
1. On the drain pan that forms the partition between the coil and condensing section.
2. On the auxiliary drain pan that forms the unit base.
A trap should be placed in the evaporator condensate drain line to prevent hot outside air from being pulled
into the evaporator section and to allow the condensate to drain away. The trap can be placed at any
location in the drain line as long as it has a minimum of 2" head as shown in Fig.2.
Drain lines running to the outside of the building should be extended beyond the wall to prevent condensate
from running down the building surface.
Condensate Drain insulation: The drain should be insulated where water drippage, due to condensation.
FIG.2-CONDENSATE DRAIN TRAP
Page 16

Duct Connections
Supply Air
The standard McQuay MWCP unit is provided with a fan outlet collar for connection of supply ductwork.
McQuay recommends that a straight duct having the same dimensions as the fan outlet be used. This duct
should be at least 3 duct diameters in length prior to installing any elbows or transition. See Table 2 for the
minimum length of straight duct required for your particular unit.
Table 2 – Duct Connection Sizes
MODEL
FAN SUPPLY
SIZE (mm)
MINIMUM LENGTH
STRAINGT DUCT (mm)
MWCP18A 225 675
MWCP30A 250 750
MWCP35A 300 900
MWCP55A 380 1140
MWCP70A 460 1380
MWCP75A 380 1140
MWCP85A 380 1140
MWCP95A 380 1140
MWCP105A 380 1140
MWCP115A 460 1380
MWCP125A 460 1380
MWCP130A 460 1380
MWCP160A 460 1380
MWCP200A 560 1680
If the required length of straight ductwork is not used and transitions or elbows are installed close to the fan
outlet, extra pressure losses will occur. These losses are referred to as "system effects". For more details on
this subject refer to A.M.C.A. Standard 210, titled "Fan and System".
Return Air
The McQuay MWCP units are designed for "free air return". The minimum returns air temperature is 55ºC.
The equipment room serves as the return air plenum. If the return air is ducted to the unit, a flex connection
must be supplied. Only return air should be ducted to the unit. Outside air should not be brought into the
return area.
Insulation
Insulate ductwork that passes through unconditioned space during cooling. Insulation should include a
vapour barrier to prevent absorption of moisture.
Page 17

Operation
General
The McQuay MWCP unit is designed for single power source connection. No separate supply is required for
the controls. The units are supplied for use on 380/415V-3Ph-50Hz or 460V-3Ph-60Hz power supply. The
control voltage for the control panel operation is 220~240V-1Ph-50Hz/60Hz.
Caution!
• The unit must not be restarted within 3 minutes after shutting down.
• Make sure that the unit is properly grounded by checking the ground terminal.
• Each system contains factory mounted, wired, adjusted and tested controls required to operate and
protect the unit.
• The control system includes compressor overload protection, motor winding protection, high and low
pressure cutouts, to guard against compressor damage due to high discharge head pressure and
system leakage.
• The unit has a single point power connection with each compressor circuit being individually fused. This
will permit additional compressors to operate when on compressor are down.
Page 18

Electrical Data
Install electrical wiring in accordance with the National Electric Code and/or local regulations. A fused
disconnect switch must be used in a separate circuit from the main power panel. The switch should be
reasonably close to the unit for convenience in servicing.
Field and elementary wiring diagrams associated with the McQuay MWCP units are shown in page 17~22.
The electrical data is shown in the wiring diagrams.
NOTE: Elementary wiring diagrams are subject to change without notice.
Table 3 - Motor Size
MODEL MOTOR SIZE (kW) MODEL MOTOR SIZE (kW)
MWCP18A 0.55 (0.37) MWCP95A 5.5
MWCP30A 1.1 MWCP105A 5.5
MWCP35A 2.2 (1.5) MWCP125A 7.5
MWCP55A 3(2.2) MWCP130A 7.5
MWCP70A 4(3) MWCP160A 11
MWCP75A 4 MWCP200A 7.5 X 2
MWCP85A 4
Table 4 – Motor Electrical Data
MOTOR 380V-3P-50Hz 415V-3P-50Hz 460V-3P-60Hz
SIZE
(kW) FLA LRA FLA LRA FLA LRA
0.37 1.17 5.57 1.07 5.1 0.94 4.47
0.55 1.53 7.65 1.40 6.86 1.26 6.55
1.1 2.94 16.16 2.69 14.80 2.24 14.54
1.5 3.70 21.30 3.39 19.50 2.92 19.14
2.2 5.08 32.10 4.65 29.40 4.20 32.50
3 6.72 43.90 6.15 40.20 5.40 46.00
4 8.70 59.40 8.00 54.50 7.20 60.00
5.5 11.90 81.60 10.90 74.40 9.49 67.38
7.5 15.70 104.00 14.40 95.00 11.90 85.68
11 22.60 153.00 20.70 140.00 17.80 122.82
After Installation But Prior To Start Up
1. Visually check power wiring for size and type. It must meet all local codes and N.E.C. codes.
2. Verify that field wiring matches the 3-phase power requirements of the unit. See caution on schematic
diagram in the control panel.
3. Check the unit visually for indication of leaks in the refrigerant circuit.
4. Check the drive alignment of the pulleys using the four-point method prior to adjusting belt tension (see
page 23 for alignment and belt tension).
5. Check the fan wheel position in the scroll, by rotating the fan manually. If any rubbing occurs, make
necessary corrections.
6. Install all panels on the air side of the unit after internal unit inspection is completed.
7. Be sure all sensors are installed in the ductwork (supply and return) and in the cooling water lines.
Check to see that all piping such as cooling water and drains are completed and tested. The steam and
drain traps must be installed.
9. Verify that water pumps (cooling) function properly and that proper flows have been set.
10. Are recommended pressure taps and temperature wells installed for trouble shooting, if required.
11. Be sure cooling tower fans are wired correctly and fans are turning in the right direction.
12. Check settings of high pressure, low pressure and low limit controls. Push all manual reset buttons to
assure that controls are functional.
Page 19

Electronic Controller
1. Function Instruction
Cool / Heat / Fan Mode
Pre-select the compressor: Auto (COMP1&2&3) COMP1 COMP2 COMP3
COMP1&2 COMP1&3 COMP2&3 Auto.
Temperature setting ranging from 16ºC ~ 30ºC.
Programmable On/Off timer with 1 hour interval.
Energy saver function.
Alarm function.
A LED indicates the states of the unit.
2. Controller Panel Instruction
LED Di spl ay
Temp. Down Setting. Preset temp minimum 16℃
R
Temp. Up Setting. Preset temp maxi mum 30℃
MODE
Pressing this button will advance the mode
i n t he f ol l owi ng sequence:
COOL→ HEAT→ FAN
•••
Mai n Power ON/ OFF
Energy Saving Selection.
Ener gy Savi ng or nor mal r unni ng st at us can
be sel ect ed.
Compr essor Runni ng Mode Sel ect i on But t on
Any of t he r unni ng mode can be sel ect ed:
AUTO(COMP1&2&3) → COMP1→ COMP2→ COMP3
COMP2&3← COMP1&3← COMP1&2←
Ti me Set t i ng.
Pr eset t i me 1 t o 15 hour
Reset
FIG.3 – CONTROLLER PANEL
3. Operation
a) Finish checking all the items (after installation but prior to start up).
b) Press MODE button to select the Cool/ Heat/ Fan.
c) If required, press TIMER button to preset time.
d) Under the cooling mode, press COMP button to pre-select the compressor.
e) Press ON/OFF button to start up the unit.
In cooling, the start sequence is, switch ON 2s water pump 10s fan 1 min COMP1(if selected)
1 min COMP2(if selected) 1 min COMP3(if selected)
In heating, the start sequence is, switch ON 2s fan 5s electric heater.
In fanning, the start sequence is, switch ON 2s fan.
f) When the unit runs, you can press TEMP button or EG-SAVER button, so that the indoor temperature is
according to your requirement.
g) Shut off the unit.
In the heating mode, the sequence is, switch OFF 2s electric heater shuts off 30s fan motor shuts
off.
Page 20

4. ALARM FUNCTION
1). The controller board is designed with 10 alarm signals input and 1 alarm output AL1-AL2.
NO. Input Defect Description
Defect
Code
Defect
Respondence
Defect Indicator
1 FL-SW Flow switch open E9 System stops COOL indicator flashes quickly
2 OV-PUMP Water pump overload E8 System stops W – PUMP indicator flashes
3 OV-FAN Fan motor overload E7 System stops FAN indicator flashes quickly
4 OV-COMP3 COMP3 overload E6 COMP3 stops COMP3 indicator flashes quickly
5 OV-COMP2 COMP2 overload E5 COMP2 stops COMP2 indicator flashes quickly
6 OV-COMP1 COMP1 overload E4 COMP1 stops COMP1 indicator flashes quickly
7 HL-COMP3
8 HL-COMP2
9 HL-COMP1
10 TH (cool)
11 TH (heat)
COMP3 high/low
pressure switch open
COMP2 high/low
pressure switch open
COMP1 high/low
pressure switch open
Thermistor sensor short
or open
Thermistor sensor short
or open
E3 COMP3 stops COMP3 indicator flashes quickly
E2 COMP2 stops COMP2 indicator flashes quickly
E1 COMP1 stops COMP1 indicator flashes quickly
E0
E0
System stops
Heater off,
30s, fan
stops
COOL, HEAT indicator flashes
quickly
COOL, HEAT indicator flashes
quickly
2). When it alarms, the digital segment displays the related defect code, the alarm output AL1-AL2 is
closed with it (normal open), the buzzer beeps for a long time, the ON/OFF indicator and other related
indicator flashes quickly with it.
3). When 2 or more than 2 defects are detected at the same time, the system will do with each defect and
keep the memory, but the defect code displays the super class E0~E9.
4). When alarm signal output, press RESET switch to clear away the alarm output for convenient repair,
press RESET switch again, the system will check all kinds of alarm signals and alarm output with the
defect.
5). The system still remains the defective state when the defect is eliminated; only after pressing RESET
switch, the system recovered to the operation state.
Page 21

Wiring Diagrams
Wiring Diagrams for 50Hz
MODEL : MWCP18A/30A/35A
MODEL: MWCP55A/70A
Page 22

MODEL: MWCP75A
MODEL: MWCP95A
Page 23

MODEL: MWCP85A/105A
MODEL: MWCP115A
Page 24

MODEL: MWCP130A
MODEL: MWCP160A
Page 25

MODEL: MWCP200A
Page 26

Wiring Diagrams for 60Hz
MODEL: MWCP18A/30A/35A
MODEL: MWCP55A/70A/85A
Page 27

MODEL: MWCP105A
MODEL: MWCP115A/130A
Page 28

MODEL: MWCP160A
Page 29

Electrial Parameter (50Hz)
Model
Power Source
Power
Supply
Wire
Power Wire
(R/S/T)
Neutral
Wire
Earth Wire
MWCP
18A
MWCP
30A
MWCP
35A
MWCP
55A
380V/3N~/50Hz
MWCP
70A
MWCP
75B
MWCP
85A
Section Area
(mm 2 )
4 4 4 6 10 10 10
Quantity 3
Section Area
(mm 2 )
1.5 1.5 1.5 1.5 1.5 1.5 1.5
Quantity 1
Section Area
(mm 2 )
2.5 2.5 2.5 2.5 2.5 2.5 2.5
Quantity 1
Model
Power Source
Power
Supply
Wire
Power Wire
(R/S/T)
Neutral
Wire
Earth Wire
MWCP
95B
MWCP
105A
MWCP
115A
MWCP
125B
MWCP
130A
MWCP
160A
MWCP
200A
380V/3N~/50Hz
Section Area
(mm 2 )
16 16 16 16 16 25 25
Quantity 3
Section Area
(mm 2 )
4 4 4 4 4 6 6
Quantity 1
Section Area
(mm 2 )
4 4 4 4 4 4 4
Quantity 1
Electrical Wiring Connection (50Hz)
Thermostatic
controller
Contactor
Cooling tower
fan motor
Overload(OL1)
Breaker
Water pump
motor
Overload(OL2)
Contactor
Terminal
block
Control panel
OL1
PCB(OV-PUMP)
PCB(W-PUMP)
PCB(FL-SW)
OL2
Water flow
switch
L
L
Note:
Cooling water pipe
Operate cooling in winter,We suggest adding a Thermostatic
controller for cooling water to control the cooling tower
fan motor.Wiring connection as drawing.
Page 30

Electrial Parameter (60Hz)
Model
Power Source
Power
Supply
Wire
Model
Power Source
Power
Supply
Wire
MWCP
18A
MWCP
30A
MWCP
35A
MWCP
55A
460V/3N~/60Hz
MWCP
70A
MWCP
85A
Power Section Area
(mm 2 4 4 4 6 10 10
Wire
)
(R/S/T) Quantity 3
Section Area
(mm 2 2.5 2.5 2.5 2.5 2.5 2.5
Earth Wire
)
Quantity 1
MWCP
105A
MWCP
115A
460V/3N~/60Hz
MWCP
130A
MWCP
160A
Power Section Area
(mm 2 16 16 16 25
Wire
)
(R/S/T) Quantity 3
Section Area
(mm 2 4 4 4 6
Earth Wire
)
Quantity 1
Electrical Wiring Connection (60Hz)
Thermostatic
controller
Contactor
Cooling tower
fan motor
Overload(OL1)
Breaker
Water pump
motor
Overload(OL2)
Contactor
Terminal
block
Control panel
OL1
PCB(OV-PUMP)
PCB(W-PUMP)
PCB(FL-SW)
OL2
Water flow
switch
L
L
Note:
Operate cooling in winter,We suggest adding a Thermostatic
controller for cooling water to control the cooling tower
fan motor.Wiring connection as drawing.
Cooling water pipe
31

Fan Performance Curve
Supply Air Blower Adjustment
The RPM of the supply air blower will depend on the required CFM, the unit accessories and the static
resistance of both the supply and the return air duct system. With this information, the RPM for the supply air
blower can be determined from the fan performance curves.
Knowing the required blower RPM and the blower motor HP, the supply air motor pulley can be determined.
After the supply air blower motor is operating, adjust the resistance in both the supply and the return duct
systems to balance the air distribution throughout the conditioned space.
Drive Alighment
Belt Adjustment
FIG.4 – ALIGNMENT AND BELT TENSION
To determine the deflection force required use the formula: Deflection = Belt Span/64
CAUTION: 1. Do not over tighten the belts or the bearings may be come damaged. The best tension for a
belt drive is the lowest tension at which the belts will not slip under the highest required load.
2. The belts should be checked at a certain time in case too loose.
Table 5-Belt Tensioning Information
SUPER GRIPBELTS
Belt Cross
Section
SPZ
SPA
Small P.D. Deflection Force (N)
Range (mm) Min. Max
56~95
100~140
80~132
140~200
13
20
25
35
20
25
35
45
SPB
112~224
236~315
45
65
65
85
32

Panel Checks
A. Verify 3 phases’ power to unit.
B. Close units disconnect and verify that crankcase heaters are energized. Allow the heater to remain on a
minimum of 24 hours before attempting startup. This is important to assure no refrigerant is in the oil
startup. Fail to do this could cause compressor failure.
Initial Start Up
After the operator has familiarized itself with the sequence of operation for the unit and all options provided,
the unit can be put in operation. Proceed as follows.
1. Energize cooling tower water pump and tower fans.
2. Turn the fan switch to the ON position.
3. The “Sequence of Operation” instruction covered are shown in the control wiring diagrams.
4. If no unusual noise or adverse conditions exist allow the unit to run. If these conditions do exist, turn off
the unit and investigate cause.
Take an air flow measurement in the straight duct off the unit discharge using a pitot tube. This
measurement should be taken about three quarters (3/4) of the way down the straight duct off the fan, just
before any transition or elbow. If a condition of low or high air flow exists, a pulley change may be required.
Once it is ascertained that the air quantity leaving the unit is at the design, the thermostats should be set to
the desired space temperature. The system should now function as designed.
33

MODEL : MWCP18A
TOTAL PRESSURE - Pa
RPM
SUPPLY AIR VOLUME – CMH(1000’S)
VELOCITY PRESSURE -Pa
MODEL : MWCP30A
TOTAL PRESSURE - Pa
RPM
SUPPLY AIR VOLUME – CMH(1000’S)
VELOCITY PRESSURE -Pa
Page 34

MODEL : MWCP35A
TOTAL PRESSURE - Pa
RPM
SUPPLY AIR VOLUME – CMH(1000’S)
VELOCITY PRESSURE -Pa
MODEL: MWCP55A/75A/85A/95A/105A
(MWCP75A/85A/95A/105A Use Double Blowers)
TOTAL PRESSURE - Pa
RPM
SUPPLY AIR VOLUME – CMH(1000’S)
VELOCITY PRESSURE -Pa
Page 35

MODEL : MWCP70A/115A/125A/130A/160A
(MWCP115A/125A/130A/160A Use Double Blowers)
TOTAL PRESSURE - Pa
RPM
SUPPLY AIR VOLUME – CMH(1000’S)
VELOCITY PRESSURE -Pa
MODEL : MWCP200A Use Double Blowers
TOTAL PRESSURE - Pa
RPM
SUPPLY AIR VOLUME – CMH(1000’S)
VELOCITY PRESSURE -Pa
Page 36

Maintenance
General
At initial startup and periodically during operation, it will be necessary to perform certain routine service
checks to assure the unit functions properly. This is also the best way to avoid unnecessary downtime and
expense.
Routine maintenance should include the following:
1. Tighten all belts, screws, and wire connections.
2. Clean evaporator coils mechanically or with cold water, if necessary. Usually any fouling is only matted
on the entering air face of the coil and can be removed by brushing.
3. Align or replace belts if needed.
4. Clean or replace filters as needed.
5. Check for blockage of condensate drains.
6. Check power and control voltages.
7. Check running amperage.
8. Check operating temperatures and pressures.
9. Check and adjust temperature and pressure controls.
10. Check operation of all safety controls.
Condensers
The frequency of cleaning depends on so many variables that it is impossible to recommend a schedule.
Some will need cleaning once a year and in rare cases, cleaning will be required several times a year. The
shell & tube condensers can be cleaned not only by mechanical methods but also by chemical methods due
to its construction.
McQuay does not recommend any particular chemical preparation. The same treatment may not be
applicable to all installations. But in any case:
a) Use only preparations from an established, reliable source.
b) Follow directions exactly, particularly regarding amounts to use and flushing or neutralizing procedure
after cleaning.
Proper operation cooling tower overflow rate should be checked frequently. If a tower is operated with
insufficient overflow, the resulting mineral concentration in the water can cause rapid and heavy fouling
inside the condenser tubes. This condition will necessitate frequent cleaning and could lead to severe
corrosion. Chemical additives, including those to stop algae and related growths, should be obtained only
from a reputable, established supplier, and use specifically according to directions. Excessive treatment of
the water can cause more harm than none at all. Pumps, piping, and the tower any damaged in addition to
the condenser.
Double check the system to make sure that fouling is actually causing the trouble. High head pressure alone
does not mean a fouled condenser. The following possibilities should always be checked before cleaning is
undertaken.
1. Refrigerant overcharge.
2. Air in system or faulty head pressure gauge; (check standby pressures against refrigerant tables)
3. Incorrectly set, or defective, water regulating valve; (check its setting)
4. High water temperatures entering condenser; (check tower fan and system)
Page 37

Trouble Shooting
PROBLEM POSSIBLE CAUSE ACTION
Lack of Cooling
Effect
1. Faulty compressor or lack of
compression.
2. Temperature of air entering
evaporator too high.
3. Fouled condenser and/or
evaporator tube surface.
4. Low refrigerant charge.
5. Improper air flow through
evaporator.
6. Room thermostat not operating
properly.
1. Check discharge pressure for
compression. Inspect compressor
and replace if necessary.
2. Reduce load to design kW value.
3. Inspect surfaces and clean.
4. Repair refrigerant leak, add
refrigerant.
5. Determine flow and adjust correctly
belt tension.
6. Inspect thermostat and replace if
necessary.
Tripping of
Compressor(s)
A. Due to Low Pressure Cut-out
1. Reduced air flow through
evaporator.
2. Low refrigerant charge.
3. Restricted refrigerant line.
4. Faulty low-pressure cut-out or
improper setting.
B. Due to High Pressure Cut-out
1. Air in refrigerant system.
2. Excess refrigerant charge.
3. Faulty high-pressure cut-out or
improper setting.
C. Due to Compressor Overload Protector tripping
1. Inspect surface & clean, check
evaporator fan drive.
2. Repair refrigerant leak, add
refrigerant.
3. Determine the cause of restriction
and repair.
4. Readjust or replace.
1. Re-evacuate refrigerant system and
charge with new refrigerant.
2. Bleed off excess refrigerant.
3. Readjust or replace.
Excessive belt
"scream" when
fans start up
1. Compressor over-current, under
voltage or single phasing.
2. Excessive discharge pressure.
3. Compressor over-heating due to low
refrigerant.
4. Compressor motor has a winding
shorted.
5. Liquid refrigerant in compressor
causing valve plate damage and
lack of compression.
6. Defective overload protector.
1. Slipping belts.
1. Check electrical supply, contractors,
wires and rectify fault.
2. See section B above.
3. Check refrigerant charge (fix leak),
add if necessary.
4. Replace compressor.
5. Check that crankcase heater is
functioning properly.
6. Replace protector.
1. Apply 'Grako Sprazon' belt
dressing.
Note:
This condition service which should be attempted only by qualified service personnel. Contact
your nearest McQuay service representative.
Page 38

REGISTERED
S&E
ISO 9002
©2003 McQuay International +1 (800) 432-1342 www.mcquay.com