McQuay PFS 155C Installation Manual

Installation Manual

Water-Cooled Dual Compressor Screw Chiller

Installation Manual PFS 155C through PFS 210C, R-22 PFS 235C through PFS 315C, R-410A 60 Hertz

IM 692-1

Group: Chiller Part Number: 629955 Effective: May 1997

Supersedes: IM663-1

IM683 IM692

Table of Contents

Introduction........................................................................................................... 3

Receiving and Handling...............................................................................................................3

Installation ............................................................................................................. 4

Location and Mounting................................................................................................................4

Compressor Condensation............................................................................................................4

Vibration Isolators .......................................................................................................................4

Evaporator and Condenser Water Piping ......................................................................................7

Water treatment ...........................................................................................................................7

Head pressure control, tower system.............................................................................................7

Head pressure control, well water system .....................................................................................8

Relief Valve Piping ......................................................................................................................8

Temperature and Water Flow Limitations.....................................................................................9

Evaporator Freeze Protection .......................................................................................................9

Condenser Protection and Design Considerations.........................................................................9

Chilled Water Thermostat............................................................................................................ 9

Refrigerant Charge ......................................................................................................................9

Detection of Loss of Flow...........................................................................................................10

Glycol Solutions.........................................................................................................................10

Evaporator and Condenser Water Flow and Pressure Drop..............................12

Physical Data........................................................................................................27

Dimensional Data.................................................................................................30

Field Wiring.........................................................................................................44

General Information ..................................................................................................................44

Pre-Start-up .........................................................................................................51

Sequence of Operation .........................................................................................51

Initial Conditions .......................................................................................................................51

Off Conditions...........................................................................................................................52

Alarm........................................................................................................................................52

Initial Start-up...........................................................................................................................52

Load Recycle .............................................................................................................................53

2 PFS 155C - 315C IM 692-1

Introduction

McQuay StarGate™ water-cooled chillers are completely assembled, factory wired, evacuated, charged, tested and ready for installation. Each unit consists of a water-cooled condenser with integral subcooler, twin accessible semi-hermetic single screw compressors, replaceable tube shelland-tube evaporator, and complete refrigerant piping. Liquid line components included are manual liquid line shutoff valves, charging valves, filter-dryers, liquid line solenoid valves, sightglass/moisture indicators, and electronic expansion valves. Other features include compressor heaters, and an advanced fully integrated microprocessor control system.

automatic operation, (the high and low pressure controls are external from the electrical control center). Compressors are protected by solid-state overload protection and over temperature protection. Field installed fused disconnect switch (furnished by others) offers additional protection.

Receiving and Handling

Inspect the unit immediately after receipt for possible damage. The unit is shipped FOB factory and all claims for handling and shipping damage are the responsibility of the consignee. Leave the shipping skid in place until the unit is in final position. This will aid in handling the equipment. Use extreme care when rigging the equipment to prevent damage to the control center, or refrigerant piping. See Dimensional Data for the center of gravity of the unit.

rigging eyes are located (see Figure 1). Use spreader bars between the rigging lines to prevent damage to the control center.

The electrical control center includes all safety and operating controls necessary for dependable

Lift the unit by fastening the rigging hooks to the four corners of the evaporator where the

Figure 1, Rigging Eyes

Rigging Eyes

IM 692-1 PFS 155C - 315C 3

Installation

CAUTION

Installation must be performed by qualified personnel who are familiar with local codes, regulations, and experienced with this type of equipment

Start-up by McQuayService is included on all units sold for installation within North America excluding Mexico. Two weeks prior notification of start-up is required. The contractor should obtain a copy of the Start-up Scheduled Request Form from the sales representative or from the nearest McQuayService office.

Location and Mounting

Mount the unit on level concrete or steel base. Service clearance (at either end of the unit) is 12 feet for units with 10 feet long shells, 14 feet for units with 12-feet long shells and 16 feet for units with 14 feet long shells. Evaporator and condenser tubes are rolled into the tube sheets to permit replacement. Clearance at all other points, including the top, is 3 feet.

Make certain the floor or structural support is adequate to support the full operating weight of the complete unit. Optional rubber-in-shear pads, or spring isolators can be ordered for use under each corner of the base members. It is not necessary to bolt the unit to the mounting slab or frame work; although mounting holes are provided in the unit support at the four corners.

Compressor Condensation

Condensation occurs on the compressor surface when the temperature of the compressor surface is lower than the ambient dew point temperature. Drain pans with drain connections are provided underneath each compressor to collect the condensate. The compressor motor housing extends past the drain pans. Install a floor drain close to the unit to collect condensate from motor housing and condensate pans.

Vibration Isolators

Optional vibration isolator pads are shipped with the unit for field installation. These pads provide minimal isolation. Vibration isolators are recommended on all upper level installations where vibration transmission is a consideration. When vibration isolators are used, install springs under the main unit supports. Adjust spring so the upper housing clears lower housing by at least 1/4” (6mm) and not more than 1/2” (1 3mm). If hold-down bolts are not used, install a rubber anti-skid under isolators. Install vibration eliminators in water piping to reduce piping strain, vibration, and noise. Table 1 lists spring and rubber-in-shear isolators for all PFS unit sizes.

4 PFS 155C - 315C IM 692-1

Table 1, Vibration Isolators (PFS150B - 215B)

Isolator Isolator Per Location

1 2 3 4

Rubber-in-Shear

Spring

RP-4 RP-4 RP-4 RP-4

CP-4-28 CP-4-28 CP-4-28 CP-4-28

Figure 2, Isolator location

Table 2, Isolators (PFS150B - 215B)

Color Recom.

Isolator Type Of McQuay Max Ld

Stripe Part No. Lb. (Kg)

Rubber-In-

Shear

Spring CP-4-28 Green 0058051328 3600 (1633)

Note: The spring is fully compressed at about 5400 lb (2449 Kg).

RP-4 Green 0021639803 3300 (1497)

Figure 3 and Figure 4 give dimensions required to secure each McQuay isolator section to the mounting surface. The maximum loads for each unit are shown in Table 3.

Figure 3 , Rubber-in-Shear Isolator

IM 692-1 PFS 155C - 315C 5

Figure 4,Spring Flex Isolator

Table 3, Weights for Standard Shell Units

Unit U X V W

155-210

Short Shell

235-315

Short Shell

155-210

Standard Shell

235-315

Standard Shell

155-190

Long Shell

200,210

Long Shell

235-315

Long Shell

2007 2412 2213 2660 2292 2841 2498 3095 2105 2475 2477 2913 2564 3060 2935 3501 3236 3107 3819 3667 2988 3182 3339 3556 3153 3468 3480 3827

Figure 5, Corner Weight Locations

6 PFS 155C - 315C IM 692-1

Evaporator and Condenser Water Piping

PFS evaporators and condensers are equipped with either victaulic or flange connections. The installing contractor must provide matching connections.

CAUTION

Remove the solid-state temperature sensor and thermostat bulbs from the wells to prevent damage to those components when welding on the victaulic or flange connections.

Connect the condenser with the inlet water entering at the bottom to maximize subcooling. The

condenser water will discharge from the top connection.

Support piping to reduce weight and strain on the fittings and connections. Be sure piping is adequately insulated. Install a cleanable 20-mesh water strainer in evaporator and condenser water piping. Install enough shutoff valves to permit draining water from the evaporator or condenser without draining the complete system.

CAUTION

Freeze Notice: The evaporator and condenser are not self-draining. Both must be blown out.

Include thermometers at the inlet and outlet connections and air vents at the high points of piping. The water heads can be interchanged (end for end) allowing water connections to be made at either end of the unit. Use new head gaskets when interchanging water heads. When water pump noise is objectionable, use rubber isolation sections at both the inlet and outlet of the pump. Vibration eliminator sections in the condenser inlet and outlet water lines are not normally required. Where noise and vibration are critical, and unit is mounted on spring isolators, flexible piping connections are necessary.

Water treatment

If unit is operating with a cooling tower, clean and flush cooling tower. Make sure tower "blowdown" or bleedoff is operating. Atmospheric air contains many contaminants which increases the need for water treatment. The use of untreated water may result in corrosion, erosion, sliming, scaling, or algae formation. A water treatment service is recommended. McQuay International is not responsible for damage or faulty operation from untreated or improperly treated water.

Head pressure control, tower system

The minimum entering water temperature to the condenser must not be lower than 70°F (21.1°C) at full tower water flow. If lower temperature water is used, the flow must be reduced proportionally. Use a three-way bypass valve around the tower to modulate the condenser water flow. Figure 6 shows a three-way pressure actuator water regulating valve used for cooling applications. This regulating valve will assure an adequate condensing pressure if the inlet condenser water temperature falls below 70°F). An optional AOX-4 board located in the MicroTech panel will control a cooling tower bypass valve or a varible speed condenser pump.

IM 692-1 PFS 155C - 315C 7

Head Pressure Control, Well Water System

When using city or well water for condensing refrigerant, install a normally closed direct acting water regulating valve in the outlet piping of the condenser. This regulating valve will assure an adequate condensing pressure if the inlet condenser water temperature falls below 70°F. The condenser service valve provides a pressure tap for the regulating valve. The valve can modulate in response to head pressure. On shutdown, the valve closes, preventing water from siphoning out of the condenser. Siphoning causes condenser waterside drying and accelerates fouling. If a valve is not used, Figure 7 illustrates the recommendation of a loop at the outlet. Size the loop height (H) to offset the negative pressure caused by the siphoning effect. A vacuum breaker may be required.

Figure 6, Bypass valve

Figure 7, Well Water System

Relief Valve Piping

Follow the requirements of ANSI/ASHRAE Standard 15-1994 for relief valve piping. The condenser relief valve assembly consists of a tree valve and two relief valves. The tree valve must be fully front or back seated to ensure only one relief valve is available for discharge.

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Temperature and Water Flow Limitations

PFS units are designed to operate in conditions from 20°F (-6.7°C) to 50°F (10°C) leaving water temperature on the evaporator side and 70°F (21.1°C) to 95°F (35°C) entering water temperature on the condenser side.

Glycol in the evaporator is required on all applications below 40°F (4.4°C) leaving evaporator fluid temperature. The maximum allowable water temperature to the cooler in a non-operating cycle is 105°F (40.6°C). The non-operating leaving condenser water temperature maximum is 115°F (46.1°C). Flow rates below the minimum values shown in the evaporator and condenser pressure drop curves may cause freeze-up problems, scaling and poor control. Flow rates above the maximum values shown in the evaporator and condenser pressure drop curves will result in unacceptable pressure drops, excessive nozzle and tube erosion and possibly cause tube failure.

Evaporator Freeze Protection

When freeze protection is a concern, do the following:

1. If the unit will not be operated during the winter, drain and flush the evaporator and chilled

water piping with glycol . Drain and vent connections are provided on the evaporator.

2. When using a cooling tower, add glycol solution to the chilled water system. Freeze point

should be approximately 10°F (5.6°C) below minimum design ambient temperature.

Note: Freeze damage is not considered a warranty failure and is not the responsibility of McQuay International.

3. Insulate field water piping, especially on the chilled water side.

Condenser Protection and Design Considerations

If pond or river water is used as a condensing medium and the water valves leak, the condenser and liquid line refrigerant temperature could drop below the equipment room temperature on the "off" cycle. This problem occurs when cold water continues to circulate through the condenser and the unit remains off due to satisfied cooling load. If this occurs:

1. Cycle the condenser pump off with the unit.

2. Verify the liquid line solenoid valves are operating properly.

Chilled Water Thermostat

The PFS water-cooled chiller is equipped with the MicroTech leaving water controller. Be careful when working around the unit to avoid damaging lead wires and sensor cables. Check lead wires before running the unit. Avoid rubbing the lead wires on the frame or other components. Verify the lead wires are firmly anchored. If the sensor is removed from the well for servicing, do not wipe off the heat conducting compound supplied in the well.

Refrigerant Charge

All units are designed for use with R-22 or R-410A and are shipped with a full operating charge. The operating charge for each unit is shown in the Physical Data Table.

IM 692-1 PFS 155C - 315C 9

Detection of Loss of Flow

NOTE: Water pressure differential switches are not recommended for outdoor applications.

The preferred means for detecting loss of flow is the use of factory-mounted pressure differential switches for the evaporator and condenser.

A flow switch is available from McQuay (part number 00175033-00). It is a “paddle” type switch and adaptable to any pipe size from 3” (76mm) to 8” (203mm) nominal. Two flow switches are required. Mount the flow switch in either the entering or leaving water line of the evaporator and condenser. Certain minimum flow rates are required to close the switch and are listed in Table

4. Installation should be as shown in Figure 8.

Figure 8, Flow Switch

Flow direction

marked on

switch

1" (25mm) NPT

Tee

Note: The procedure does not specify the type of glycol. Use the derate factors found in Table 5 for corrections when using ethylene glycol and those in Table 6 for propylene glycol.

5" (127mm)

Connect the normally open contacts of the flow switch in the unit control center at terminals 62 and 63. Flow switch contact must be suitable for 24 VAC, low current (16ma).

Table 4, Flow Switch Minimum Flow Rates

Nominal Pipe Size Min. Required Flow to

(inches) Activate Switch - GPM (L/s)

5 58.7 (3.7) 6 79.2 (5)

Glycol Solutions

CAUTION

Use industrial grade glycols only. Do not use an automotive grade antifreeze. 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.

To determine flow rate for the evaporator in GPM (L/s), and pressure drop through the cooler, use the following formulas and tables.

1. Capacity - Multiply the chiller's capacity with water by the capacity correction factor (Cap) to

find the chiller's capacity with glycol.

2. GPM - To determine evaporator GPM (or Delta-T) knowing Delta-T (or GPM) and tons:

24 ×

tons glycol

Glycol GPM = (from table)

( )

−

Delta T

flow

10 PFS 155C - 315C IM 692-1

For metric applications: L/s - To determine evaporator L/s (or Delta-T) knowing Delta-T (or L/s) and kW:

Glycol L / s = (from table)

Delta T

418. × −

flow

3. Pressure Drop - To determine pressure drop through the cooler when using glycol, enter the appropriate water pressure drop curve (begin on page 12 at the actual glycol flow. Multiply the water pressure drop found there by pressure drop adjustment factor (PD) to obtain corrected glycol pressure drop.

4. To determine the unit power consumption, multiply the unit kW/TR with water by the (kW/TR) factor. 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. A minimum of 25% solution by weight should be used for protection against corrosion.

Note: The effect of glycol in the condenser is negligible. As glycol increases in temperature, its properties approach those of water. For selection purposes, there is no derate in capacity for glycol in the condenser.

Table 5, Adjustment factors for ethylene glycol

% Freeze Point

E.G. °F °C CAP. kW/TR COP Flow PD

10 26 -3 0.991 1.005 0.995 1.013 1.070 20 18 -8 0.982 1.010 0.990 1.040 1.129 30 7 -14 0.972 1.014 0.986 1.074 1.181 40 -7 -22 0.961 1.016 0.984 1.121 1.263 50 -28 -33 0.946 1.021 0.979 1.178 1.308

Table 6, Adjustment factors for propylene glycol

% Freeze Point

P.G. °F °C CAP. kW/TR COP Flow PD

10 26 -3 0.987 1.005 0.995 1.010 1.068 20 19 -7 0.975 1.010 0.990 1.028 1.147 30 9 -13 0.962 1.017 0.983 1.050 1.248 40 -5 -21 0.946 1.026 0.975 1.078 1.366 50 -27 -33 0.929 1.039 0.962 1.116 1.481

Application Considerations

The chilled water loop must contain an adequate volume of water to prevent short cycling the chiller. Minimum water volume can be determined using the following formula:

Design GPM X 15 Minutes

Number of Compressors

Volume of Water=

IM 692-1 PFS 155C - 315C 11

Evaporator and Condenser Water Flow and Pressure Drop

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 cutouts. Flow rates exceeding the maximum values shown can cause erosion on the evaporator water connections and tubes.

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.

Do not vary the water flow through the evaporator while the compressor(s) are operating. MicroTech control setpoints are based on constant flow.

Figure 9 , Evaporator 2-pass (short shell)

12 PFS 155C - 315C IM 692-1