Introduction

McQuay StarGateTM 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, multiple accessible semi-hermetic single screw compressors. replaceable tube shell-and-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.

The electrical control center includes all safety and operating controls necessary for dependable 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 S w itch (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.

Lift the unit by fastening the ri gging hooks to the four corners of the evaporator where the rigging eyes are located (see Figure I ). Use spreader bars between the ri gging lines to prevent damage to the control center.

Figure I, Rigging Eyes

Rigging eyes

Rigging eyes

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3

Installation

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 a level concrete or steel base. Service clearance (at either end of the unit) is 14 feet for units with 12-foot long standard shells and 18 feet for units with 16-foot long optional 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

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 l lists spring and rubber-in-shear isolators for all PFS unit sizes

4 IM 663

Evaporator and Condenser Water Piping

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

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.

CAUllUN

I

Freeze Notice: Neither the evaporator nor the condenser is 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 (2

I _

1°C).

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

663 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

8

Figure 7, Well Water System

Loop required when no regulating valve is used

r-

/

V-d

H f

Kl- ld

Service valve

Y

From main

+ condenser pump

Direct acting water regulating valve

Relief Valve Piping

Follow the requirements of ANSUASHRAE 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.

IM 663

Temperature and Water Flow Limitations

PFS units are designed to operate in conditions from 2 1 “F (-8.9”C) to 55°F (1O’C) leaving water temperature on the evaporator side and 70°F (2

I.

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 10j°F (40.6”(Z). The non-operating leaving condenser water temperature maximum is 115°F

(46.1 “C). Flow rates below the minimum values may cause freeze-up problems, scaling and poor control. Flow rates above the maximum values 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 HCFC-22 and are shipped with a full operating charge. The operating charge for each unit is shown in the Physical Data Table.

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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 ofthe evaporator and condenser. Certain minimum flow rates are required to close the switch and are listed in Table 5.

Installation should be as shown in Figure 8.

Figure 8. Flow Switch

Connect the normally open contacts ofthe flow switch in the unit control center at terminals 62 and 63. Flow switch contact must be suitable for 23 VAC. low current ( I bma).

Table 5, Flow Switch Minimum Flow Rates

Nominal Pipe Size

(inches)

5

6

Min. Required Flow to

Activate Switch

- GPM (L/s)

58.7 (3.7)

79.2 (5)

Glycol Solutions

Note: The procedure does not specify the type of glycol. Use

ihe

der& factors found in Table 6 for corrections when using ethylene glycol and those

in Table 7

for

propylene glycol.

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 flou rate for the evaporator in CPM (L/s). and pressure drop through the cooler, use the following formulas and tables.

3

-.

1. Capacity - Multiply the chiller’s capacity with water b>, the capacity correction factor (Cap) to tind the chiller’s capacity with glycol.

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

Gl~col

<iPM =

73 x to/?s( &m/)

llelm - 7‘ x j70M$from talk)

10

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For metric applications:

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

UI’

Glycol L : s =

4. IX x nvllL1 - r x ,/10lr’

(from

tahlc)

3. Pressure Drop - To determine pressure drop through the cooler when using glycol, enter the appropriate water pressure drop curve (begin on page

I2 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 of2590 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 6, Adjustment factors for ethylene glycol

Tab/e 7, Adjustment factors for propylene glycol

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 pressure drop (2-pass and 3-pass)

Flow Rate (Us)

12

I

1 Standard Shall B-pass/

/

I hi i i i t

200 WI3 a0

Flow Rate (GPM)

saoaoo7moo~lom

IM 663

Field Wiring

CAUtlON

PFS unit compressors are single direction rotation compressors. For this reason proper phasing of electrical power is essential. Electrical phasing must be A, B, C clockwise for electrical phases 1, 2 and 3 (A=L1 ,B=L2,C=L3) The unit is supplied with single point factory power connection and includes one MotorSaver phase failure, phase reversal protective device that will prevent operation of the unit with incorrect power phasing. The MotorSaver is factory wired and tested. Do not alter the wiring to the MotorSaver.

General Information

Wiring must comply with all applicable codes and ordinances. Warranty is void if wiring is not in accordance with specifications.

Copper wire must be used for all wiring

The PFS is supplied standard with the main power wirin g for single point power connection. A single large power terminal block is provided. Wiring within the unit is sized according to the National

Electrical Code. A single field-mounted disconnect (supplied by others) is required. An optional factory mounted transformer for the 1

15

volt control circuit may have been provided.

Main power must enter the control panel at the location indicated on the unit illustration.

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21

Pre-Start-up

3.

4.

5.

1.

2.

Open all electrical disconnects and check electrical connections are tight.

Verify water piping flow directions are correct and properly connected at the evaporator and condenser.

Using a phase tester, verify electrical phasing is A-B-C clockwise (A=L I, B=L2.C=L3).

Verify unit power supply is within

1 0 %

of nameplate rating.

Verify power supply wiring is the correct size and has a minimum temperature insulation rating of

75°C.

6.

7.

Verify all mechanical and electrical inspections have been completed according to local code.

Make certain all auxilliary control equipment is operative and an adequate cooling load is available.

Check all compressor valve connections for tightness.

8.

9.

10.

Open compressor suction valve until backseated. (This is an optional valve)

Open discharge shutoff valve until backseated

I 1.

Vent air from the evaporator and condenser water system piping.

12.

Open all water tlow valves and start chilled water pump.

13.

14.

Check all piping for leaks.

Flush the evaporator and condenser system piping.

Sequence of Operation

The following sequence of operation is typical for McQuay models PFS 150B through PFS2 15B rotary screw water chillers. The sequence may vary depending on the software revision or various options that may be installed on the chiller.

Initial Conditions

Before energizing the control box do the following:

1. Verify the two control circuits are powered through the primary fuses FU1 and FU2 and the secondary fuse FU3.

2.

Verify the power developed through the transformer CPT in the starter is 120 Vac on the secondary.

3. Verify front panel switch is in the off position.

When applying power to the control for the first time do the following:

1.

Open the left door and the top door to each control box.

2. Observe when power is applied the display lights up and when the Unit Status screen appears the

EXV board lights rapidly sequence closed.

3. Listen for the stepper motors closing with a ratcheting sound.

IM 663 25

4. The Unit Status Screen on the display should indicate Off: Front Panel SW.

5.

Verify the control setup for the network of two control boxes as follows:

26

*** 1s unit Model size

Move Master control communication connector fi-oni B to A port and disconnect the RSX2 connector (the one with the

juniper

from pin 2 - pin 6)

Second Screen Nevt Item

Slave

Address

Mode= Auto:Local Auto- Network

Note. If address switches were changed then reset power off

/ on for both boxes

Off Conditions

With power to the controller there are several “off’ states as follows:

Off: Manual

When the setpoint in menu “I

I

Control Mode” is set to the Mode= Manual Off to change set the Mode= Auto: Network or any other running mode.

Off: Front Panel SW When the panel switch is in the “Stop” position. To change move the switch to “Auto” position.

Off Alarm

Remove the alarm state then clear the alarm to remove this

off

state.

Alarm

The alarm light on the front panel illuminates when the particular control receives an active alarm state. That particular control will be locked out of compressor start or operation. The other control will still be able to start.

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Initial Start-up

CAUTION

Initial start-up must be performed by McQuayService personnel.

4.

5.

1.

2.

3.

6.

Set up control as described in the initial conditions.

Turn front panel switch to Auto position (chilled water flow pump relay will energize).

If the field installed flow indicator does not indicate chilled water flow after 30 seconds, the alarm output wi

I l be

energized.

The chiller will start w hen the leaving water temperature is 3’F above the Active Setpoint.

The controller starts the compressor W ith the least starts while in auto Iead-lag setting. energizes the liquid in_jection solenoid and motor coolin g solenoid. energizes the suction injection solenoids. and de-energizes the crank case heaters.

Suction injection will turn off when the following conditions have been met:

The discharge superheat drops below 3r “F. the Liquid Presence sensor shows liquid, and the

Absolute Pres. ratio is greater than I.2 (

Abs. Condenser Psia i Abs. Evaporator Psia)

7.

The unit status moves from:

EvapOn-Recirc **Sec to All Systems Off to MCR Started to Pre-purge to Open

Solenoid to Running Min Amp Lim to Running: % Cap 50

If additional cooling capacity is required then the controllers will add capacity by changing the capacity control solenoids outputs 7. 8. and 9 and maintaining a close balance in amp capacity between compressors after both compressor are running. The lag compressor will come on after the lead compressor amps have exceeded the setpoint to turn on the lag for the defined lag time (see menu

23 on the master controller).

Load Recycle

As the load drops. the controls will unload the compressors until the compressors amps drop below the lag cutoff point for the delay time required. The control will then shut off the lag compressor and further reduction in load will cause the leaving water ternperature to drop 3 ’ F below the active setpoint which will cause the compressor to turn off on Load Recycle and the display will show

Waiting For Load and the chilled water pump will remain on.

I

I

27