Air-Cooled Scroll Compressor Water Chillers Installation, Operation and Maintenance Manual

Air-Cooled Scroll Compressor Water Chillers Installation, Operation and Maintenance Manual

Introduction

General Description

McQuay air-cooled water chillers are complete, self-contained automatic refrigerating units. Every unit is completely assembled, factory wired, charged, and tested. Each unit consists of air-cooled condensers, Copeland Compliant Scroll

hermetic compressor, brazed plate-to-plate evaporator, and complete refrigerant piping. Liquid line components include sight-glass/moisture indicator, solenoid valve, and thermal expansion valve. Other features include a compressor heater, and evaporator heater for chilled water freeze protection.

The electrical control center includes all equipment protection and operating controls necessary for automatic operation. Condenser fan motors are three-phase (except single-phase on No. 1 fan with

SpeedTrol option) and started by their own contactors and have inherent overload protection. The compressor has solid-state motor protection for inherent thermal overload protection except Model

AGZ 010 that has internal line breakage.

Inspection

Check all items carefully against the bill of lading. Inspect all units for damage upon arrival. Report shipping damage and file a claim with the carrier. Check the unit nameplate before unloading to be sure it agrees with the power supply available. Units are shipped FOB factory and McQuay is not responsible for physical damage after unit leaves the factory.

Note: Unit shipping and operating weights are listed on pages 13 and 14.

Installation

Note: Installation is to be performed by qualified personnel who are familiar with local codes

and regulations, especially concerning refrigerant release to the atmosphere.

WARNING

Sharp edges and coil surfaces are a potential hazard. Avoid contact with them.

Handling

Be careful to avoid rough handling of the unit. Do not push or pull the unit from anything other than the base. Block the pushing vehicle away from the unit to prevent damage to the sheet-metal cabinet

and end frame (see Figure 1).

To lift the unit, lifting slots are provided in the base of the unit. Arrange spreader bars and cables to

prevent damage to the condenser coils or cabinet (see Figure 2).

IOMM AGZ1 AGZ 010A through 034A

3

Figure 1, Suggested Pushing Arrangement

Blocking required across full width

Figure 2, Suggested Lifting Arrangement

4

Location

Unit Placement

AGZ units are for outdoor applications and can be mounted on a roof or at ground level. Set units on a solid and level foundation. For roof-mounted applications, install the unit on a steel channel or Ibeam frame to support the unit above the roof. For ground level applications, install the unit on a substantial base that will not settle. A one-piece concrete slab with footings extended below the frost line is recommended. Be sure the foundation is level (within 1/2” [13 mm] over its length and width).

The foundation must support the operating weights listed in the Physical Data Tables on pages 13 and

14.

Since its operation is affected by wind, the unit should be located so that its length is parallel with the prevailing wind. If this is not practical, use field fabricated wind deflectors.

Service Access

Each end of the unit must be accessible after installation for periodic service. Compressors, filterdriers, and liquid line solenoid valve are accessible from the end of the unit. High-pressure, lowpressure, and motor protector controls are on the compressor. Most operational, safety and starting controls are located in the unit control box.

The fan deck with the condenser fans and motors can be removed from the top of the unit.

AGZ 010A through 034A IOMM AGZ1

IOMM AGZ1

Clearances

The flow of air to and from the condenser coil must not be limited. Restricting airflow or allowing air recirculation will result in a decrease in unit performance and efficiency. There must be no obstruction above the unit that would deflect discharge air downward where it could be recirculated back to the inlet of the condenser coil. The condenser fans are propeller type and will not operate with ductwork on the fan outlet.

Install the unit with enough side clearance for air entrance to the coil and for servicing. Provide service access to the evaporator, compressors, electrical control panel and piping components as shown in

Figure 3. Do not block access to the unit

with piping or conduit.

Do not allow debris to accumulate near the unit. Air movement may draw debris into the condenser coil causing air starvation.

Give special consideration to low ambient operation where snow can accumulate.

Keep condenser coils and fan discharge free of snow or other obstructions to permit adequate airflow.

Figure 3, Clearance requirements

4 Ft.

(1220mm)

Clearance for

Service Access

4 Ft. (1220mm)

Clearance for Air Inlet

4 Ft. (1220mm)

Clearance for Air Inlet

4 Ft.

(1220mm)

Clearance for

Service Access

The recommended minimum side clearance between two units is 8 feet (2440mm).

Sound Isolation

The low sound levels of the AGZ chiller are suitable for most applications. When additional sound reduction is necessary, locate the unit away from sound sensitive areas. Avoid locations beneath windows or between structures where normal operating sounds may be objectionable. Reduce structurally transmitted sound by isolating water lines, electrical conduit and the unit itself. Use wall sleeves and rubber isolated piping hangers to reduce transmission of water or pump noise into occupied spaces.

Use flexible electrical conduit to isolate sound through electrical conduit. Spring isolators are effective in reducing the low amplitude sound generated by the Discus semi-hermetic compressors and for unit isolation in sound-sensitive areas.

The unit must not be installed in a pit or enclosure that is deeper or taller than the height of the unit unless extra space is provided. The minimum clearance on each side of the unit is 6 feet (1828mm) when installed in a pit. The pit cannot be deeper than the unit.

The minimum clearance to a side wall or building taller than the unit height is 6 feet (1828mm) provided no solid wall above 6 feet (1828mm) tall is closer than 12 feet (3658mm) to the opposite side of the unit.

AGZ 010A through 034A

5

6

Vibration Isolators

Vibration isolators are recommended for all roof-mounted installations or wherever vibration transmission is a consideration. The isolators can be purchased from McQuay by the part numbers shown in the table.

The unit should be initially on shims or blocks at the listed free height. When all piping, wiring, flushing, charging, etc. is completed, the springs are adjusted upward to loosen the blocks or shims that are then removed.

A rubber anti-skid pad is part of the isolator. Installation of spring isolators requires flexible piping connections and at least three feet of flexible conduit to avoid straining the piping and transmitting vibration and noise.

Table 1, Recommended Vibration Isolators

AGZ UNIT

010A – 034A

ISOLATOR

TYPE

Rubber-in-shear

ISOLATOR

PART NO.

021639703

021639701

010A – 017A

020A – 034A

Spring Isolators

Spring Isolators

047792726

047792726

047792727

Note: See dimension drawing for location of isolators

NUMBER

REQUIRED

2

2

4

2

2

KIT of FOUR

PART NO.

350014857

350014835

350014839

LOCATION

LF, RF

LB, RB

All

LF, RF

LB, RB

ISOLATOR

DESCRIPTION

RP-3 Green

RP-3 Red

CP-1-26

CP-1-27

CP-1-26

Control

Panel

Corner Weights

AGZ

Unit

Model

010A

013A

017A

020A

025A

029A

034A

RF LF RB LB

261 367 159 223

372 526 184 260

402 568 200 282

484 621 226 291

499 646 232 301

621 647 326 339

678 784 334 386

Chilled Water System

Water Piping

Local authorities can supply the installer with the proper building and safety codes required for safe and proper installation.

Install piping with minimum bends and changes in elevation to minimize pressure drop. Consider the following when installing water piping:

1. Vibration eliminators to reduce vibration and noise transmission to the building.

2. Shutoff valves to isolate the unit from the piping system during unit servicing.

3. Manual or automatic air vent valves at the high points of the system. Install drains at the lowest points in the system.

AGZ 010A through 034A IOMM AGZ1

IOMM AGZ1

4. A means of maintaining adequate system water pressure (expansion tank or regulating valve).

5. Temperature and pressure indicators located at the unit to aid in unit servicing. Pressure gauge taps must be installed in the chilled water inlet and outlet piping or as shown in Figure 4.

6. A strainer or other means of removing foreign matter from the water before it enters the pump.

Place the strainer 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 keep system performance up.

7. A 40-mesh strainer is required in the water line just before the inlet of the evaporator. This will help prevent foreign material from entering and decreasing the performance of the evaporator.

CAUTION

If separate disconnect is used for the 110V supply to the evaporator heating cable, mark the disconnect clearly to ensure disconnect is not accidentally shut off during cold seasons. This could cause a failure of the evaporator.

8. The brazed plate evaporator has a thermostat and heating cable to prevent freeze-up down to

-20

°

F (-29

°

C). It is suggested that the heating cable be wired to a separate 110V supply circuit.

As shipped from the factory, the heating cable is wired to the control circuit. Protect all water piping to the unit from freezing.

9. If the unit is used as a replacement chiller on a previously existing piping system, flush the system thoroughly before unit installation. Regular water analysis and chemical water treatment on the evaporator is recommended immediately at equipment start-up.

10. When glycol is added to the water system for freeze protection, the refrigerant suction pressure will be lower, cooling performance less, and water side pressure drop greater. If the percentage of glycol is high, or if propylene is used 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 38

°

F (3.3

°

C). Reset the freezestat setting to approximately 4 to 5 degrees F (2.3 to 2.8 degrees C) below the leaving chilled water setpoint

temperature. See the section titled “Glycol Solutions” on page 9 for additional information

concerning glycol.

11. Perform a preliminary leak check before insulating the piping and filling the system.

12. Piping insulation should include a vapor barrier to prevent condensation and possible damage to the building structure.

Figure 4, Typical Field Evaporator Water Piping

Air

Vent

Strainer

Inlet

P

Vibration

Eliminators

Isolation

Valves

Outlet

Flow

Switch

Drain

NOTES:

1. Chilled water piping within the unit enclosure must be insulated in the field.

2. Piping should be supported independently of the unit and be installed per local codes.

AGZ 010A through 034A

7

8

System Volume

It is important to have adequate water volume in the system to provide an opportunity for the chiller to sense a load change, adjust to the change and stabilize. As the expected load change becomes more rapid, a greater water volume is needed. The system water volume is the total amount of water in the evaporator, air handling products and associated piping. If the water volume is too low, operational problems can occur, including rapid compressor cycling, rapid loading and unloading of compressors, erratic refrigerant flow in the chiller, improper motor cooling, shortened equipment life and other undesirable occurrences.

For normal comfort cooling applications, where the cooling load changes relatively slowly, we recommend a minimum system volume of five minutes times the flow rate (GPM). For example, if the design chiller flow rate is 120 GPM, we recommend a minimum system volume of 600 gallons

(120 GPM x 5 minutes).

Since there are many other factors that can influence performance, systems may successfully operate below these suggestions. However, as the water volume decreases below these suggestions, the possibility of problems increases.

Variable Chilled Water flow

Variable chilled water flow systems are not recommended for this class of equipment due to limited unloading capability.

Flow Switch

Mount a water flow switch in the leaving water line to shut down the unit when water flow is interrupted.

Figure 5, Flow Switch Installation

A flow switch is available from McQuay

(part number 017503300). It is a “paddle” type switch and adaptable to pipe sizes down to 1 1/4” (32mm) nominal. Certain minimum flow rates are required to close

the switch and are listed in Table 2. Install

the switch as shown in Figure 5. Connect

the normally open contacts of the flow switch in the unit control center at terminals

4 and 5. There is also a set of normally closed contacts on the switch that can be used for an indicator light or an alarm to indicate when a “no-flow” condition exists.

Freeze protect any flow switch that is installed outdoors. Follow installation instructions provided with the flow switch. Calibrate the flow switch to open at one-half of nominal flow rate.

NOTE: Differential pressure switches are not recommended for outdoor installation.

Table 2, Flow Switch Settings

Pipe Size

Minimum

Adjustment

Maximum

Adjustment

Flow

No

Flow

Flow

No

Flow inch mm gpm

Lpm gpm

Lpm gpm

Lpm gpm

Lpm

1 1/4

32

4.8

18.2

3.0

11.3

7.7

29.1

5.9

22.3

1 1/2

38

6.3

22.7

3.6

13.6

10.0

37.9

7.0

26.5

2

51

9.9

37.5

5.9

22.3

15.8

59.8

11.0

41.6

2 1/2

63

15.3

57.9

9.5

36.0

23.7

89.7

17.0

64.3

3

76

24.4

92.4

15.4

58.3

35.5

134.4

29.2

110.5

4

102

33.3

126.0

21.1

79.9

61.4

232.4

37.7

142.7

AGZ 010A through 034A IOMM AGZ1

Water Connections

The unit has 3-inch holes for the chilled water piping to enter the unit. The connections are made to the evaporator water connections located within the unit. Water piping within the unit must be field insulated.

Refrigerant Charge

All units are designed with HCFC-22. See the nameplate for specific refrigerant used. Units are shipped with an operating charge. The operating charge (using HCFC-22) for each unit is shown in in

the Physical Data Tables on pages 13 and 14.

Unit Component Location

Control Panel

Tandem Scroll

Compressors

IOMM AGZ1

Evaporator

Charging Valve

Solenoid Valve, Expansion Valve

Optional Hot Gas Bypass Valve Filter Drier

Glycol Solutions

The use of glycol antifreeze solutions will decrease unit capacity and increase the pressure drop through the cooler. See Product Manual PM AGZ1 for specific ratings and correction factors.

CAUTION

Do not use automotive grade antifreeze. Industrial grade glycols must be used. Automotive antifreeze contains inhibitors that will cause plating on the copper tubes within the chiller evaporator. The type and handling of glycol used must be consistent with local codes.

Evaporator Water Flow and Pressure Drop

Evaporator flow rate must fall between the minimum and maximum values shown in the evaporator

pressure drop curve, Figure 6. Flow rates outside of these limits result in a chilled water Delta-T

outside the operating range of the controller.

Measure the chilled water pressure drop through the evaporator at field-installed pressure taps. It is important not to include the effect of valves or strainers in these readings.

Varying chilled water flow through the evaporator while the compressors are operating is not recommended.

AGZ 010A through 034A

9

Figure 6, Evaporator Water Pressure Drop Curve

AGZ 010

AGZ 020

AGZ 025

AGZ 029

AGZ 034

AGZ 013

AGZ 017

10

AGZ

Model

010

013

017

020

025

029

034

Minimum Flow

Flow Rate gpm L/s

Pressure Drop ft. kPa

15.0

0.9

2.4

7.1

19.5

1.2

24.0

1.5

30.0

1.9

34.5

2.2

1.5

1.7

2.3

1.8

4.5

5.0

6.8

5.3

40.7

2.6

49.8

3.1

1.7

1.6

5.0

4.7

Nominal Flow

Flow Rate gpm L/s

Pressure Drop ft. kPa

24.0

1.5

5.8

17.3

31.2

2.0

38.4

2.4

48.0

3.0

55.2

3.5

3.7

4.1

5.6

4.3

11.0

12.2

16.7

13.0

65.0

4.1

79.7

5.0

4.0

3.9

12.1

11.7

Maximum Flow

Flow Rate gpm L/s

Pressure Drop

ft. kPa

40.0

2.5

15.2

45.5

52.0

64.0

80.0

92.0

3.3

4.0

5.0

5.8

9.6

10.7

14.5

11.4

28.9

32.1

43.4

34.3

108.4

6.8

132.8

8.4

10.9

32.6

10.4

31.2

AGZ 010A through 034A IOMM AGZ1

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