Water-Cooled Packaged Chillerswith Helical Rotary Compressors

Installation, Operation, and Maintenance Instructions

Form 6186

WCOX056-107B

TABLE OF CONTENTS

PAGE1. GENERAL INFORMATION ........................................................................................................... 2

1.1 Receiving and Inspection ...................................................................................................... 21.2 Rigging and Moving ............................................................................................................... 21.3 Dimensional Data .................................................................................................................. 31.4 Application Precautions ......................................................................................................... 3

2. INSTALLATION............................................................................................................................. 32.1 Foundation ............................................................................................................................ 32.2 Vibration Isolation ................................................................................................................. 32.3 Water Piping Connections ..................................................................................................... 52.4 Electrical Wiring .................................................................................................................... 52.5 Controls ................................................................................................................................ 52.6 Request for Start-Up Representative ..................................................................................... 5

3. OPERATION ................................................................................................................................. 63.1 System Water Flow Rate ....................................................................................................... 63.2 Seasonal Shut-Down Procedure ............................................................................................ 63.3 Seasonal Start-Up Procedure ................................................................................................ 63.4 Safety Relief Valves .............................................................................................................. 63.5 Refrigeration Cycle ................................................................................................................ 63.6 Oil System .......................................................................................................................... 103.7 Hydraulic Capacity Control System ..................................................................................... 103.8 Freeze Protection ................................................................................................................ 10

4. ELECTRICAL .............................................................................................................................. 114.1 60 Hz Electrical Data .......................................................................................................... 114.2 Wiring Diagram .................................................................................................................... 124.3 Typical Operation ................................................................................................................ 124.4 Microcomputer Controller .................................................................................................... 124.5 Control & Safety Functions ................................................................................................. 17

5. MAINTENANCE ........................................................................................................................... 225.1 General ............................................................................................................................... 225.2 Periodic Inspection .............................................................................................................. 225.3 Monthly Inspection .............................................................................................................. 225.4 Water Side Cleaning of Vessels ........................................................................................... 235.5 Electrical Malfunction .......................................................................................................... 235.6 Charging .............................................................................................................................. 235.7 Troubleshooting ................................................................................................................... 245.8 Sample Log Sheet ............................................................................................................... 26

WCOX SERVICE PARTS LIST ........................................................................................................ 27

INTRODUCTION

This equipment is a factory built and tested packaged chillerdesigned for the purpose of cooling water or other non-corrosive liquid. The liquid to be cooled is to be circulatedthrough the tubes of a refrigerant evaporator (hereafterreferred to as a cooler) where the temperature is reduced tothe desired level. The heat absorbed by the refrigerant in thecooler is rejected via the condenser where it raises thetemperature of another liquid stream (usually water) beingcirculated through the tubes. This heat is usually rejected viaa cooling tower or closed circuit cooler.

To assure satisfactory operation and to avoid damage to theunit, the installation should be made by a qualified refrigera-tion mechanic. It is

assumed that the reader of this manual and those whoinstall, operate and maintain this equipment have a basicunderstanding of the principles of air conditioning, refrigera-tion and electrical controls. These instructions are general innature and are for standard catalog units. Non-standard unitsmay vary in some respects from these instructions.

Your Dunham-Bush packaged chiller has been manufacturedunder a careful quality control system. It has been perfor-mance tested at the factory at specified field operatingconditions as a final verification of reliability. If it is installed,operated and maintained with care and attention to theseinstructions, it will give many years of satisfactory service.

LIFT FROM THESE LOCATIONS ONLY!

CONDENSER

COOLER

NOTES:

DO NOT SKID UNIT UNLESS UNIT ISEQUIPPED WITH FACTORY INSTALLEDSKID OPTION.

FIGURE 1RIGGING INSTRUCTIONS

1. GENERAL INFORMATION

1.1 RECEIVING AND INSPECTION

The unit should be inspected immediately, in the presence of thecarrier’s representative, for any evidence of damage duringshipping. Any damage should be noted on the carrier’sdelivery receipt before it is signed. A damage claim shouldthen be filed by the purchaser against the delivering carrier as

all shipments are made at the purchaser’s risk. The receivinginspection instructions. (Form 9214), sent with the installationinstructions, should also be filled out at this time and forwardedto the Dunham-Bush, Inc., North American Service Department,Harrisonburg, VA 22801.

1.2 RIGGING AND MOVING

Each unit has been carefully tested and inspected at the factorywhere every precaution was taken to ensure that it reaches itsdestination in perfect condition. It is very important that theinstallers,

movers, and riggers use the same care in handlingthe unit. A forklift may only be used to move the unit whenequipped with the optional skid. The unit can be lifted by a cranefrom lifting holes provided on the vessel tubesheets. For properrigging, see Fig. 1.

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1.3 DIMENSIONAL DATA

Dimensional outline drawings of the packages are shown in Fig-ure 4. Note especially the space and

clearance requirements necessary for servicing the unit.

1.4 APPLICATION PRECAUTIONS

The following instructions are intended to help assure proper andsuccessful application of your water

chilling machines.

1.4.1 Chilled Water Flow

The Dunham-Bush WCOX Packaged Water Chiller is designed fora constant chilled water flow rate, even when the cooling load isvarying. The machine will generally perform satisfactorily with steadyflow rates deviating from design by as much as +10% / -50%. How-ever, varying water flow rates can cause control instability whichwill result in undesirable system effects, particularly poor control ofleaving chilled water temperature. If two-way valves are used tocontrol flow through cooling coils, some means such as an auto-

matic modulating valve should be provided in the system tomaintain steady flow through the cooler.

If the chilled water system is arranged for the dual purpose of cool-ing and heating, the cooler must incorporate valves to prevent theflow of hot water through it. This can be done with either manual orautomatic shutoff valves, but the method of control must be suchthat water temperature entering the cooler never exceeds 90 F.

1.4.2 Water Cooled Condensers

The water cooled condenser is also designed for constant waterflow rate, and should be supplied with the design GPM ±10%. Thecondenser must be protected from rapid changes in temperatureas well. Fluctuating flow rate or temperature will cause unstablecontrol of the machine, resulting in poor control of leaving chilledwater temperature. If a cooling tower is used to reject heat from thecondensing water loop, it must be controlled to provide an enteringcondensing water temperature which does not change rapidly anddoes not go below 60 F. One or more of the following methods maybe used to control the tower:

1.4.2.1 A modulating three-way valve which by-passes towersprays at low load and low ambient temperature.

1.4.2.2 Tower fan staging in response to a thermostat in the towersump. Fan thermostat should have a differential of at least 20 F toavoid short-cycling.

1.4.2.3 A modulating three-way valve which by-passes the cool-ing tower to blend warm leaving condenser water with cold towerwater.

1.4.3 Condensing Water Treatment

Condensing water tends to leave silt, algae and mineral deposits inthe condenser tubes. This fouling gradually decreases unit efficiency.For this reason, a program of water treatment should be employed.

Also, at regular intervals depending on water quality, the unit shouldbe shut down, condenser heads removed and tubes cleaned. SeeSection 5.4.

2. INSTALLATION

2.1 FOUNDATION

A flat, level concrete foundation or floor capable of supporting theweight of the unit must be provided.

Weights are given in Table 1. The unit must be levelled to within1/16" per foot for proper operation

Where structure-borne vibration may be of concern, it is recom-mended that the unit be mounted on vibration isolators. Springisolators are available for this unit as optional equipment. If springisolators are installed, it is also necessary to provide isolation in

condenser water and chilled water pipes by means of flexibleconnectors and in main power supply conduit through use offlexible conduit. Isolation of piping and electrical conduit isdesirable in any event, to avoid noise transmission.

2.2 VIBRATION ISOLATION

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Table 1 PHYSICAL SPECIFICATIONS

WCOX 056-108 Unit Model WCOX056 WCOX066 WCOX080 WCOX089 WCOX107 Compressor 2510 2512 2515 2516 2519 60 Hz RPM 3550 3550 3550 3550 3550 Shipping Wt. (lb) - Std. Vessels 23,620 26,914 31,764 34,962 40,975 Operating Wt. (lb) - Std. Vessels 25,670 29,394 34,754 38,282 44,965 Approx. R-22 Charge, lbs. 1100 1200 1400 1500 1600 Standard Vessel Nomenclature B5 C5 D5 E5 G5

Standard Cooler Model EF30163 EF34163 EF37163 EF39163 EF43163 Design press. Water Side (PSIG) 200 (Non Code) 200 (Non Code) 200 (Non Code) 200 (Non Code) 200 (Non Code)Design Press. R-22 Side (PSIG) 255 255 255 255 255 Min. GPM/PD (Ft., 1 Pass) 852/0.9 1021/0.9 1234/0.9 1366/0.9 1645/0.9 Min. GPM/PD (Ft., 2 Pass) 426/1.7 510/1.7 617/1.7 683/1.7 823/1.7 Min. GPM/PD (Ft., 3 Pass) 286/2.7 349/2.8 433/2.9 462/2.7 561/2.7 Max. GPM/PD (Ft., 1 Pass) 4260/17.3 5104/18.2 6169/17.9 6830/17.2 8225/18.1 Max. GPM/PD (Ft., 2 Pass) 2130/32.0 2552/32.7 3084/32.0 3415/32.4 4113/32.3 Max. GPM/PD (Ft., 3 Pass) 1303/43.5 1560/43.1 1908/43.9 2165/44.6 2624/45.1 Standard Condenser Model CD30163 CD34163 CD37163 CD39163 CD43163 Design Press. Water Side (PSIG) 200 (Non Code) 200 (Non Code) 200 (Non Code) 200 (Non Code) 200 (Non Code)Design Press. R-22 Side (PSIG) 300 300 300 300 300 Min. GPM/PD (Ft., 1 Pass) 884/1.1 1064/1.1 1278/1.1 1416/1.0 1687/1.1 Min. GPM/PD (Ft., 2 Pass) 442/2.0 532/2.0 639/2.0 708/2.0 844/2.0 Max. GPM/PD (Ft., 1 Pass) 4420/20.1 5318/21.1 6391/20.8 7079/20.0 8436/21.0 Max. GPM/PD (Ft., 2 Pass) 2210/37.4 2659/38.2 3196/37.5 3539/37.8 4218/37.8

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2.3 WATER PIPING CONNECTIONS

After the unit has been levelled and isolators (if any) installed and adjusted, connect cooler and condenser water piping. Piping must be properly supported to avoid stress on unit water connections. Install air vent valves in all high connections on cooler and condenser heads. Install drain valves in similar low points to facilitate gravity draining of the system. It is important that water systems be cleaned before start-up to avoid collecting debris in cooler and condenser.

The best way to do this is to install wye strainers in both systems upstream of the unit. After filling systems with water, bleed trapped air from the various vent valves. Check for proper flow rates by measuring water pressure drop across heat exchangers and reading GPM from charts, Figure 2. Compare measured GPM's with values specified on purchase order.

2.4 ELECTRICAL WIRING

In connecting power wiring to the unit, the following precautions should be taken: All field wiring is to be in accordance with the

National Electric Code and must comply with state and local codes.

Check unit wiring for damage and all terminal connections for tightness. Unit terminal blocks are to be connected with copper conductors only, sized per ampacity listed on unit data plate.

Connections to unit should match the unit nameplate in volts, phase, and Hertz. Voltage must not vary beyond ±10% of nameplate value and voltage imbalance between phases must not exceed 2% at any time during operation of the unit.

Phase sequence to connections L1 L2 L3 shall be in that order. Check with Amprobe phase sequence adapter PSA-1 or equivalent. For minimum circuit ampacity and fuse size, consult unit nameplate. All units have running overload protection as standard. When the transformer option is not supplied, a direct connected 115 VAC ±10% circuit must be supplied. The over current protection for the circuit must be 30A. Use #10AWG copper conductors. Wire to terminal block 1TB. Use terminal #2 for connection of the ground supply conductor.

2.5 CONTROLS

2.5.1 Connections

Controls which are to be field installed should be connected in accordance with the appropriate wiring diagram accompanying the unit. The following connections should be made where applicable: 2.5.1.1 Connect a set of normally open auxiliary contacts

from chilled water pump contactor into unit controls as shown on unit wiring diagram.

2.5.1.2

2.5.1.2 Install a chilled water flow switch (paddle type recommended) in straight length of chilled water piping to avoid turbulence. Connect in same electrical circuit as 2.5.1.1. 2.5.1.3 For control of condensing water pumps, connect contacts supplied in unit in series with condensing water pump starter coil.

2.5.2 Settings All controls are factory set, however operating control settings are not always applicable under all operating conditions. For recommended control settings, se

wiring diagram accompanying unit. Safety controls must be set to factory recommendations.

2.6 REQUEST FOR START-UP REPRESENTATIVE

After the installation has been completed and checked, Form 9180 must be filled out and sent to North American Service Department of Dunham-Bush, Inc. for authorized start-up representative to perform the initial start-up of the Dunham-Bush packaged chiller. The purchaser will have competent service and operating personnel in attendance to assist in the work involved, and also to be trained in the service and maintenance of this unit. (During the warranty period, the manufacturer is responsible for parts only upon proof of defective workmanship or manufacture). Following receipt of the signed Form 9180, a representative will be sent to the customer. He will

inspect the installation to determine whether it meets specified customer personnel in its operation and maintenance for the length of time specified in the purchase contract. NOTE: Sump oil heaters should be energized for a minimum of 24 hours and the oil sump temperature must be at a minimum of 100 F (38 C) prior to arrival of start-up representative. This will ensure that the oil is warm enough to vaporize any dissolved refrigerant and that the oil is within the normal operating temperature range.

WARNING

The compressor(s) should be started initially ONLY under the direct supervision of an Authorized Dunham-Bush, Inc., Start-Up Representative.

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3. OPERATION

3.1 SYSTEM WATER FLOW RATE The quantity of chilled water being circulated can be measured quite accurately (±5%) by determining the water pressure drop through the cooler and reading GPM from cooler pressure drop curve, Figure 2. Connect reliable pressure gauges to valves installed in cooler entering and leaving water vent connections

and read pressure difference with chilled water pump in operation. Condenser water flow rate can be measured in the same way. An alternate method of determining GPM is to measure pressure difference from pump inlet to outlet and read GPM from pump curve.

3.2 SEASONAL SHUT-DOWN PROCEDURE

3.2.1 If the unit is to be shut down for a prolonged period (a month or more), the power supply to the unit may be de-energized to conserve energy. 3.2.2 The cooling tower may be drained to avoid

freezing. If the unit is located in an area where the ambient temperature constantly remains above freezing, the condenser need not be drained. It is better to leave the condenser and cooler filled with water during shutdown period. If the unit is located where ambient temperature will be below freezing, drain all water thoroughly, removing all vent and drain

3.2.3

plugs from both heads of each vessel, and blow out tubes with compressed air. NOTE: Simply draining is not sufficient. Stagnant water may cause serious corrosion. 3.2.3 It is recommended that an oil sample be taken from the compressor and submitted for laboratory analysis. Dunham-Bush offers this service in its Oil Kare Program. This analysis should be done at the beginning and end of each operating season, or every six months if the unit is used year round.

3.3 SEASONAL START-UP PROCEDURE

When the unit is to be started up after being shut down for a prolonged period: 3.3.1 Check unit for evidence of rust or corrosion. Clean surfaces and repaint as necessary. Repair insulation if necessary. 3.3.2 Energize power supply to unit. Unit must be energized for 24 hours in order to warm up oil sump before starting. Control circuit power switch should be off during this period to prevent compressor operation. Clean water side heat transfer surface of condenser and cooler by removing heads and brushing tubes. 3.3.3 Check water circuits to see that cooling tower is ready for operation, and both circuits are filled. 3.3.4

Start pumps and check for flow in both cooler and condenser. 3.3.4 Turn control circuit power switch on, turn compressor switch on, and press reset on computer keyboard. Compressor should start after start-up clock times out and leaving water temperature should be automatically controlled. Check refrigerant charge and check for normal suction and discharge pressures. 3.3.5 Have a trained service mechanic check the function of all control setpoints. Check signal lights for proper operation. 3.3.6 Take oil sample from the sump and submit it for laboratory analysis.

3.4 SAFETY RELIEF VALVES

Each pressure vessel is protected by a safety relief valve as required by ASME Code. The condenser has a dual manifold. One valve in this manifold is active, the other standby. If the active valve starts to

leak, simply screw the manifold valve to the opposite extreme, which will activate the standby valve. Local codes may require that all safety relief valves be piped to the outdoors. Never install a hand valve in a safety relief vent line.

3.5 REFRIGERATION CYCLE

Following is the normal sequence of operation for a unit installed in a typical air conditioning system and served by a cooling tower. Refer to Figure 4, the piping schematic for a WCOX 056-107 unit. The large screw compressor discharges warm, high pressure gas through a discharge service valve (1) into the condenser, where the oil is separated. The gas is condensed outside tubes, rejecting heat to cooling tower water flowing inside the tubes. The liquid refrigerant drains to the bottom of the condenser and exits into the liquid line. The refrigerant flows by a charging valve (2), past a condenser drain sight glass (3), and through a modulating ball valve (4) which is

driven by a modutrol motor (5). The motor adjusts the valve to maintain an appropriate level in the cooler, determined by a liquid level float switch (6), and measurement of compressor discharge superheat. From the modulating valve, liquid refrigerant flows into the flooded cooler, where it boils, cooling the water flowing inside the cooler tubes. Vapor from the boiling refrigerant flows up the suction pipe through a suction check valve (7) into the compressor where it is compressed and starts the cycle again.

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Figure 2Water Pressure Drop Data

Two Pass

One Pass

FLOW (GPM)

FLOW (GPM)

PR

ES

SU

RE

DR

OP,

FE

ET

OF

WA

TE

RP

RE

SS

UR

E D

RO

P, F

EE

T O

F W

AT

ER One Pass

Three Pass

CONDENSER

FLOODEDEVAPORATORS

7

Two Pass

Figure 3Dimensional Data

8

9

CONDENSER

COOLER

REFRIGERATION CIRCUIT

PUMPED OIL CIRCUIT

OIL RETURN CIRCUIT

UNLOADER CIRCUIT

Figure 4Typical Piping Schematic

3.6 OIL SYSTEM

3.6.1 Oil Supply System The compressor's oil is supplied from a sump in the condenser by an external pump. This oil is used to actuate the slide valve and lubricate the bearings, rotors, and seals in the compressor. Figure 4 illustrates oil from the condenser sump feeds past an oil charging port (8), through an isolation valve (9), a suction strainer (10), and the oil pump (11). From there it passes through a filter (12), another isolation valve (9), and into the compressor's main oil port. Seal oil leaves the injection manifold to be cooled in the seal oil cooler (16) in the condenser. A check valve (14) prevents backflow. A bypass valve (15) should be adjusted to keep oil returning to the compressor below 120 F at all times. Pressurized oil is also fed from another port on the compressor to the main oil injection supply for the rotors

through a main oil injection adjusting valve (13) which is usually fully open, and must be open at least one full turn during operation to lubricate the rotors. Electric resistance heaters are located in the oil sump in the condenser vessel and serve to vaporize excess refrigerant that would otherwise dilute the oil during shutdown by heating the oil to a suitable temperature. The heaters must be energized a minimum of 24 hours prior to start up of the unit. Two oil sump sight glasses are provided. During normal operation or shutdown, the bottom glass should indicate a partial oil level. The top glass should always be empty.

3.6.2 Oil Return System The oil separator discharges a very small amount of oil mist along with refrigerant. This oil is carried into the cooler. As shown in Figure 4, oil-rich refrigerant is returned from the cooler through taps in the cooler shell through an oil return valve (19), filter drier (20), into a jet pump (18) installed on

the suction line which received high pressure gas from the discharge line through a hot gas valve (17), which should be fully open. This forces the oil-rich mixture from the cooler into the suction line of the compressor. A sight glass (21) can be used to observe oil return rate.

3.7 HYDRAULIC CAPACITY CONTROL SYSTEM (SEE FIGURE 4)

The compressor has a hydraulic control system to supply the proper force necessary to actuate the capacity control slide valve, thereby regulating compressor loading. It is controlled by the NC25-4 microcomputer, which provides

signals to the load solenoid valve (25) and unload solenoid valve (22) to provide pressure to move the slide valve. Angle valves (13, 23, and 24) provide access to the solenoid valves, as well as factory adjustment of control rates.

3.8 FREEZE PREVENTION If water (or brine) is allowed to freeze within the tubes and heads of the cooler or condenser, severe damage will result; split and leaking tubes and cracked and leaking heads.

Since this damage can be extremely costly and is not covered by warranty, it is important to be mindful of freeze prevention. Three cases deserve particular attention:

3.8.1 Standby at Low Ambient Temperatures If the unit is to stand idle at ambient temperatures below 32° F, the water should be drained from cooler and condenser. A head should be removed from each vessel and the tubes blown dry with compressed air.

Gravity draining the vessel through drains in heads may not be sufficient. If cooler or condenser are served with a glycol solution, make sure the freeze temperature of the solution is lower than expected minimum ambient temperature.

3.8.2 In Operation Freezing of water in cooler tubes is a possibility if chilled water flow stops and if the low suction pressure cutout (normally set for 58 psig, or 32 F saturation) and the low water temp cutout both fail. If the chilled water flow switch and pump interlock are properly applied (See 2.5.1.1 and

2.5.1.2) the unit has four protective devices which must all fail to produce freezing of the cooler in operation. While this is unlikely, it is important to see that all these devices are functional and properly calibrated.

3.8.3 During Maintenance In transferring refrigerant within the unit, or releasing refrigerant from the unit for maintenance purposes, it is possible to freeze cooler or condenser tubes. Remember that whenever the pressure in a vessel is reduced below

58 psig, if water is not flowing, it is possible to freeze tubes. For this reason, it is a good precaution to have water flowing in both vessels whenever transferring refrigerant.

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4. ELECTRICAL 4.1 ELECTRICAL DATA

Compressor Motor Oil Pump Data Circ #1 Circ #2WCOX Line Voltage `460V'

Motor Size Volts HZ RLA LRA HP FLA Volts/PH/HZ MCA MFS MCA MFSDesignation

(1) (2) (4) (14) (15) (5) (6) (21) (22)

J 400 50 460 2900 3 6.0 400/3/50 581 1000 -- --J 460 60 460 2900 3 4.4 460/3/60 580 1000 -- --J 575 60 368 2320 3 3.6 575/3/60 464 800 -- --J 2300 60 87 560 3 4.4 460/3/60 109 175 13 15J 4160 60 51 339 3 4.4 460/3/60 64 110 13 15K 400 50 525 3250 3 6.0 400/3/50 663 1000 -- --K 460 60 525 3250 3 4.4 460/3/60 661 1000 -- --K 575 60 420 2600 3 3.6 575/3/60 529 800 -- --K 2300 60 102 668 3 4.4 460/3/60 128 225 13 15K 4160 60 59 382 3 4.4 460/3/60 74 125 13 15L 400 50 585 3625 3 6.0 400/3/50 738 1200 -- --L 460 60 585 3625 3 4.4 460/3/60 736 1200 -- --L 575 60 468 2900 3 3.6 575/3/60 589 1000 -- --L 2300 60 112 728 3 4.4 460/3/60 140 250 13 15L 4160 60 65 420 3 4.4 460/3/60 82 125 13 15M 400 50 655 4300 3 6.0 400/3/50 825 1200 -- --M 460 60 655 4300 3 4.4 460/3/60 824 1200 -- --M 575 60 524 3450 3 3.6 575/3/60 659 1000 -- --M 2300 60 120 770 3 4.4 460/3/60 150 250 13 15M 4160 60 71 450 3 4.4 460/3/60 89 150 13 15N 400 50 720 4600 3 6.0 400/3/50 906 1600 -- --N 460 60 720 4600 3 4.4 460/3/60 905 1600 -- --N 575 60 576 3700 3 3.6 575/3/60 724 300 -- --N 2300 60 140 910 3 4.4 460/3/60 175 305 13 15N 4160 60 80 518 3 4.4 460/3/60 100 175 13 15P 400 50 778 5550 3 6.0 400/3/50 979 1600 -- --P 460 60 778 5550 3 4.4 460/3/60 977 1200 -- --P 575 60 624 4056 3 3.6 575/3/60 784 300 -- --P 2300 60 150 990 3 4.4 460/3/60 188 175 13 15P 4160 60 88 580 3 4.4 460/3/60 110 1600 13 15Q 400 50 824 5600 3 6.0 400/3/50 1036 1600 -- --Q 460 60 824 5600 3 4.4 460/3/60 1035 1600 -- --Q 575 60 671 4361 3 3.6 575/3/60 843 1200 -- --Q 2300 60 168 1070 3 4.4 460/3/60 210 350 13 15Q 4160 60 94 625 3 4.4 460/3/60 118 200 13 15R 400 50 901 5800 3 6.0 400/3/50 1133 2000 -- --R 460 60 901 5800 3 4.4 460/3/60 1131 2000 -- --R 575 60 726 4719 3 3.6 575/3/60 912 1600 -- --R 2300 60 179 1170 3 4.4 460/3/60 224 400 13 15R 4160 60 102 660 3 4.4 460/3/60 128 225 13 15S 400 50 955 6310 3 6.0 400/3/50 1200 2000 -- --S 460 60 955 6310 3 4.4 460/3/60 1199 2000 -- --S 575 60 778 5057 3 3.6 575/3/60 977 1600 -- --S 2300 60 190 1198 3 4.4 460/3/60 238 400 13 15S 4160 60 109 670 3 4.4 460/3/60 137 225 13 15T 400 50 1030 6780 3 6.0 400/3/50 1294 2000 -- --T 460 60 1030 6780 3 4.4 460/3/60 1292 2000 -- --T 575 60 830 5395 3 3.6 575/3/60 1042 1600 -- --T 2300 60 203 1248 3 4.4 460/3/60 254 450 13 15T 4160 60 117 750 3 4.4 460/3/60 147 250 13 15U 400 50 -- -- 3 6.0 400/3/50 -- -- -- --U 460 60 -- -- 3 4.4 460/3/60 -- -- -- --U 575 60 -- -- 3 3.6 575/3/60 -- -- -- --U 2300 60 215 1397 3 4.4 460/3/60 269 450 13 15U 4160 60 124 806 3 4.4 460/3/60 155 250 13 15V 400 50 -- -- 3 6.0 400/3/50 -- -- -- --V 460 60 -- -- 3 4.4 460/3/60 -- -- -- --V 575 60 -- -- 3 3.6 575/3/60 -- -- -- --V 2300 60 228 1482 3 4.4 460/3/60 285 500 13 15V 4160 60 131 852 3 4.4 460/3/60 164 250 13 15

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4.2 WIRING DIAGRAM Figure 6 is a typical wiring diagram for a WCOX056-107. This may not be an accurate representation of your unit. It is best to use the wiring diagram

mounted in the package control panel. A copy of that diagram is furnished with the unit owner's manual.

4.3 TYPICAL OPERATION

In order to start a unit, the following conditions must be met: - chilled water pump running - chilled water flow switch made - customer control contact (optional) closed - control switch and compressor switch on - circuit breakers on - all safety conditions satisfied - reset pressed on microcomputer keypad - the compressor has not started within the last 20 minutes - leaving chilled water temperature 2 F or more above setpoint

- oil sump temperature is greater than 70 F.

The microcomputer starts the oil pump by energizing 4CP. If capacity indicator is below 8% and a minimum of 27 psid oil pressure is established, 15 seconds later the microcomputer signals 2CR which starts the compressor motor. Oil pressure and standby discharge pressure are then monitored to insure that a differential of at least 27 psid is maintained for 15 seconds. (The capacity indicator must also unload to less than 8%). The microcomputer then signals 2CR, which starts the compressor motor. When the compressor starts, the microcomputer monitors leaving water temperature, ramp schedule, and load limiting to control load and unload solenoids. The refrigerant level sensor and discharge temperature are used to control the refrigerant modulating motor (See 4.5.9). When minimum compressor capacity exceeds system load and water temperature falls below setpoint, the compressor and oil pump shut down.

4.4 MICROCOMPUTER CONTROLLER This unit is controlled by a microcomputer control system. The system is composed of four microcomputer boards, a display board and analog and digital sensors. The following sections describe the system and how to operate it. The display board has a 20-key keypad and a 2 x 40 LCD display. The keypad and display can be used to determine the status of the compressor, oil pump, and

refrigeration system. Various setpoints can also be displayed and altered. The status of the machine can also be monitored by a computer terminal either locally or remotely by a modem. The terminal must be able to handle RS232 communications. For more information, order Form #6372.

4.4.1 TO DISPLAY DATA FROM THE MENU 1. Press the MENU key. 2. Use the up or down arrow keys to select the type of

information desired. The main menu items are: DATE & TIME SET CONTROL POINTS ANALOG SENSORS DIGITAL SENSORS SETPOINTS A & B ALARMS AUTHORIZATION

3. Press the ENTER key. 4. Use the up or down arrow keys to select the desired data.

For control points, additional data can be viewed with the right and left arrow keys.

NOTE: When displaying analog sensors, the PAGE MODE key can be pressed to display two new analog inputs after each arrow key is pressed. Press PAGE MODE again to return to displaying one new analog in put.

4.4.2 TO RESET ALL CONTROL POINTS TO COMPUTER CONTROL

1. Press the RESET key. The display will show RESET

ALL CPs to COM MODE? N Y 2. Press the right arrow key to select Y.

3. Press the ENTER key. The reset will not be accepted if a lockout control point is active. Resolve the problem and reset again.

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Figure 6Typical Wiring Diagraml

013048A113

013048B114

4.4.3 TO DISPLAY ALARMS

1. Press the MENU key.2. Use the up or down arrow to select ALARMS.3. Press ENTER.4. The day, time, and alarm code is displayed. Alarm 1 is the

most recent alarm.5. Press the down arrow to view previous alarms.

6. To view the name of the alarm, display the digital input thatcorresponds to the alarm number. If the digital input name isSPARE, then display the control point that corresponds tothe alarm number. EX: If alarm code 29 has occurred thendisplay digital input 29 or control point 29 to determine the

failure.

4.4.4 TO BECOME AUTHORIZED

1. Select AUTHORIZATION on the main memo. Press ENTER.2. If the current status shown is VIEW, press the

authorization code (64) on the number keys.3. Press ENTER. the current status will change to PRG (pro-

gram) if accepted

1. You must be authorized and in the PROG mode. See section4.4.4.

2. Select SETPOINTS A & B on the main menu. Press ENTER.3. Use the up or down arrow keys to select the setpoint to be

changed. Press ENTER. A cursor will flash over the setpointA value.

4.4.5 TO ALTER SETPOINT DATA

4. a) If you want to change setpoint A, press in the desired newvalue and press ENTER. if the new value is within limits, it willbe stored in memory. The cursor will then move to setpoint B.b) If you do not want to change setpoint A, press ENTER.

5. Repeat 5.4 for Setpoint B

4.4.6 TO CALIBRATE TEMPERATURE AND PRESSURE SENSORS

1. You must be authorized and in the PROG mode. See Section4.4.4.

2. Display the analog sensor to be calibrated on thetop line of the display.

3. Press ENTER to show ZERO CALIBRATION value.4. Use an accurate gauge to measure the analog value when

it is stable and near design conditions.5. Determine the revised zero calibration required as follows:

Meter Reading - AI Display + Zero Calibration = New ZeroCalibration. The new zero calibration must be rounded tothe nearest whole number.

6. Press ENTER to place the cursor on the zero calibration value.7. Enter the new value from 6.5. Negative values are entered by

pressing LOWER FUNCTION +/- before the number.8. Press ENTER to store the revised zero calibration.

For example, if a suction pressure gauge shows 58 psig andthe computer displays 60.3 psig with a zero calibration of -1,then new calibration would be 58 - 60.3 + (-1) = -3.3 (-3). Sothe zero calibration should be changed to -3.

4.4.7 TO SET DATE AND TIME

1. You must be authorized. See Section 4.4.4.2. Select DATE & TIME SET on the main menu. Press ENTER to

display current date and time.3. Press ENTER key to move cursor to each date/time item.4. As each item flashes, use the number keys to enter revised

data if necessary.

5. Press ENTER to continue. The last ENTER will store the newdate and time.

WARNING: Setting the clock will cause a system reset. Theentire unit will shut down and start over again. If the change wasstarted inadvertently, press MENU key before completing thechange.

4.4.8 TO DISPLAY DATA WITHOUT ACCESSING MENU

1. Press LOWER FUNCTION.2. Press function desired (blue sub-script)3. Press item number to be displayed.

4. Press ENTER.EX: To display analog input #5, press LOWERFUNCTION< ANALOG INPUT, 5, ENTER

15

Figure 7Instruction Label

16

4.4.9 TO REVISE SCHEDULES

1. See Section 4.5.29

4.5 CONTROL AND SAFETY FUNCTIONS

4.5.1 Chilled Water Pump Interlock And Flow Switch (CWP AND CWFS)

These are field installed switches, both of which are used to en-sure chilled water flow before the unit is allowed to start. Failure ofeither one during operation will cause the compressor and oil pumpto shutdown.

A water flow alarm will be generated and RESET must be pressedto clear the alarm. NOTE: The flow switch or pump interlock cannotbe used for normal control of the unit. (See 4.5.2).

4.5.2 Customer Control Interlock

Control contacts from an external controller can be used to enableor disable operation of the unit. The wiring diagram specifies theterminals to which the contacts must be wirted.

To enable the unit, the contacts must be closed. To disable the unit,the contacts must be opened.

4.5.3 Anti-Recycle Timer (Microcomputer)

The compressor motor requires an anti-recycle time delay whichprevents restart for 20 minutes after a start. The purpose of thisfeature is to avoid frequent starts which tend to elevate the motorwinding temperature and impose undue wear on contactors.

The microcomputer will not restart the compressor motor until the20 minutes have elapsed. COFF is displayed when the compres-sor control point (1CP) is addressed, and when other conditions forcompressor start are satisfied. See Section 4.3.

4.5.4 Load Control (Microcomputer)

The microcomputer controls the leaving water temperature withina narrow deadband by pulsing load and/or unload solenoids onthe compressor. The load and unload solenoids position the slidevalve within the compressor to control its capacity. The microcom-puter determines a desired level of loading and varies pulse dura-tion depending on difference between load target and actual load.The load target is varied based on rate of approach to desiredtemperature preventing significant temperature oscillations. Thecurrent limit function (see Section 4.5.7) overrides the temperaturecontrol.

The status of the compressor can be observed by displayingthe compressor control point (1/CONTROL POINT). One ofthe following messages will be displayed:

COMP 1 LOAD Automatic loadCOMP 1 HOLD Automatic holdCOMP 1 UNLD Automatic unloadCOMP 1 OFF Off on temperature or customer

controlCOMP 1 COFF Off on timer (C lock off)COMP 1 LOFF Manual off or safety shutdown

4.5.5 Unload Start (Microcomputer)

On packages with wye-delta starters, a refrigerant bypass is re-quired at start. The microcomputer turns the bypass solenoid on

when the oil pump starts and turns it off 30 second after the com-pressor starts.

4.5.6 Ramp Control (Microcomputer)

Another feature of the microcomputer is ramp control, which is theability to vary load time of the machine from start. Often when themachine is started, the water in the chilled water circuit is warm,and the unit will go to full load quickly. With ramp control, the usercan program the computer so that it loads at a predetermined rate.This is a valuable tool, since it can help reduce power consumptionand demand charges. Two variables are used to define the rampprofile: Ramp rate and start point. Ramp rate defines the length

of time the unit takes to load from start point to full load. Startpoint is the percent of full load at which the ramp begins. Theramp rate A setpoint can be set anywhere from 0.1 to 0.4, smallervalues producing slower loading rates. The ramp start B setpointcan be set anywhere between 10 and 50%. The compressor willload quickly to this value and then follow the ramp slope fromthere. See Table 4 for ramp rates at various settings.

17

TABLE 4 Ramp Rates for Several Setpoints (in Minutes)

Ramp Start Point Setpoint RateSetpoint 10% 20% 50%

.1 30 27 17

.2 15 13 8

.3 10 9 5

.4 8 7 4

4.5.7 Current Limiting (Microcomputer)

A maximum desired current is specified by amp limit B setpoint forthe compressor. Above the B setpoint, the compressor will not load.If the amps rise above the A setpoint, the computer will give an

unload command to the compressor until the current drops belowthe A setpoint. The amp value in the A setpoint should be 10% ofRLA higher than the B setpoint.

4.5.8 Hot Gas Bypass (Factory-installed option)

When hot gas bypass has been supplied with the package, anoutput from the computer controls the solenoid. The solenoid isturned on if the target percent capacity of the compressor drops

below the hot gas bypass B setpoint. If the target percentcapacity then climbs above the hot gas bypass A setpoint, thesolenoid is turned off. Typical setpoints are 25% for the Bsetpoint and 60% for the A setpoint.

4.5.9 Refrigerant Management

The liquid line ball valve is controlled by a modulating motor (4MTR).The mod motor is positioned by the microcomputer, which is re-sponding to cooler refrigerant level via a liquid level transducer,and compressor discharge superheat by means of the dischargepressure and temperature measurements

If cooler level is sensed to be low by the transducer, the modmotor is driven open. If the level is high, the mod motor drivesthe valve closed. A drop in discharge superheat below a valuedetermined by the microcomputer causes the modulating valveto close, lowering the liquid level in the cooler.

4.5.10 High Sump Temperature Alarm

If sump temperature rises above the sump temperature limit (220°F) for 10 seconds, an alarm is generated.

The compressor is locked off and the alarm light is turned on.Resolve the problem and press RESET.

4.5.11 Control Power Loss

The microcomputer can be set up to start automatically or manuallyafter a power failure to the microcomputer. The power loss B setpointis factory set to 0.0 to allow automatic start after a control power

loss. To select manual reset, set power loss B setpoint to 1.0. Inthis case, a power loss alarm will be stored by the microcomputerand RESET must be pressed to start.

4.5.12 Low Pressure Cut-off (Microcomputer)

This function protects the unit from operating at abnormally lowcooler refrigerant pressure. The microcomputer will shut down thecompressor when cooler pressure falls below the low pressuresetpoint and turn on the alarm pilot light. A low pressure alarm

will be recorded by the microcomputer. Reset by pressing theRESET button on the microcomputer. Standard setpoint is 58psig for water systems.

4.5.13 Cooler Freeze Shutoff (Microcomputer)

If the leaving chilled water temperature drops below the freezesetpoint, the microcomputer will shut down the unit and store the

freeze alarm. After solving the problem, press RESET on themicrocomputer to clear the alarm.

4.5.14 High Pressure Cut-off (Microcomputer)

This function protects the compressor from operating at abnor-mally high discharge refrigerant pressures. The microcomputer willshut down the compressor when condenser pressure reaches thehigh pressure setpoint, and turn on the alarm indicator lamp on

the control box. The high discharge pressure alarm will be re-corded by the microcomputer. Reset by pressing the RESET but-ton on the microcomputer. Setpoint is 250 psig.

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4.5.15 Low Oil Pressure Alarm (Microcomputer)

A low oil pressure alarm is triggered by one of the following condi-tions: 1) The compressor is on and oil pressure is less than 25 psidfor 10 seconds, or 2) The oil pump is on and the compressor hasnot started within 50 seconds.

If either of the above conditions occur, the microcomputer will lock

4.5.16 Sump Heater Control

off the compressor and oil pump, and turn on the alarm light. Thelow oil pressure alarm code will be stored in the microcomputer.When the problem is resolved, press RESET to clear the alarm.See Section 5.6.2 regarding oil change.

The three oil sump heaters are controlled by two relays (3CR,4CR). When the oil pump is turned on, all of the sump heaters arede-energized (3CR and 4CR are energized). When the oil pumpturns off, 3CR is de-energized and two of the heaters turn on. If

sump temperature is less than Heater Temperature setpoint B(145 F), 4CR is also de-energized and the third heater turns on.If sump temperature rises above Heater Temperature setpoint A(150 F), 4CR is energized and the heater turns off.

4.5.17 Compressor Starter Failure

A compressor starter failure is generated if any of the starter safetycontacts open. The contacts must be wired in series and con-nected to the control panel as shown on the wiring diagram. Safetydevices on the starter may include compressor overload, under

voltage/phase failure, ground fault, shorted SCR detector, etc. Whenone of these contacts opens, digital input 5 turns on and the com-pressor is locked off on a compressor starter alarm. The alarm lightis turned on. Resolve the problem and press RESET.

4.5.18 Oil Pump Overload Protection

The oil pump overload contacts are wired into the control panel asshown on the wiring diagram. If these contacts open, digital input 6turns on and the compressor and oil pump are locked off on an

oil pump overload alarm. The microcomputer also turns on thealarm light. Resolve the problem and press RESET.

4.5.19 High Seal Oil Temperature Alarm

If seal oil temperature rises above the oil temperature limit (130°F)for 4 minutes, an alarm is generated. The compressor and oil pump

are locked off and the alarm light is turned on. Resolve theproblem and press RESET.

4.5.20 Compressor Power Control (No Stop Alarm)

The control power relay feeds power to the compressor controlcircuit. After power-up, the relay is closed to allow normal compres-sor control.

The computer will open this relay if it detects that the compressorcontactor auxiliary switch stays closed for 15 seconds when thecomputer is commanding the compressor to be off. The computerdetermines that the auxiliary switch is closed if the compressor

contactor digital input (typically #1) is displaying ON rather thanOFF. A No-Stop alarm would then be stored in the alarm history.This would indicate that either a hardware problem is forcing thecompressor to run when it should not or that the contactor statusis not being monitored correctly.

When the problem is resolved, press the RESET key to allow themachine to start.

4.5.21 Sensor Alarm ShutdownIf the computer measures an analog value that is far beyond nor-mal operating values, the compressor is shutdown. The computerthen stores the alarm code corresponding to the specific sensor

that caused the alarm. Any of these alarms indicate a problem inthe analog measurement system. After the problem is resolved,the RESET key must be pressed.

The following is a description of each sensor alarm:

1) Leaving water temperature error is triggered if sensor readshigher than 190°F for 10 seconds.

2) Suction pressure transducer error is activated if sensorreads less than -20 psig for 10 seconds. It is also triggeredif leaving water temperature is less than 60°F and suctionpressure reads higher than 150 psig for 10 seconds.

3) Discharge pressure transducer error is triggered if discharge pressure reads higher than 390 psig or lower than 5psig for 10 seconds.

4) Oil pressure transducer error is generated if the sensorreads higher than 350 psig, or lower than 5 psig, or if differential is greater than 120 psid for 5 seconds. This alarm will also trigger if the oil pump is off and oil differential is outside of the 0±5 psid band for 5 minutes.

5) Sump temperature sensor error is triggered if the sensor reads higher than 280°F or lower than 0°F for 10 seconds.

6) Seal oil temperature sensor error is generated if the sensoreads higher than 280°F or lower than 0°F for 10 seconds

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TABLE 5 HCFC-22 PRESSURE/TEMPERATURE PROPERTIES (PSIG-F)

PRESS TEMP PRESS TEMP PRESS TEMP PRESS TEMP PRESS TEMP PRESS TEMP 0 -41.4 55 30.1 110 64.4 165 88.6 220 108.0 276 124.51 -38.8 56 30.9 111 64.9 166 89.0 221 108.3 278 125.12 -36.4 57 31.7 112 65.4 167 89.4 222 108.6 280 125.63 -34.1 58 32.4 113 65.9 168 89.8 223 109.0 282 126.14 -31.8 59 33.2 114 66.4 169 90.2 224 109.3 284 126.75 -29.7 60 33.9 115 66.9 170 90.6 225 109.6 286 127.26 -27.7 61 34.7 116 67.4 171 91.0 226 109.9 288 127.77 -25.7 62 35.4 117 67.9 172 91.3 227 110.2 290 128.38 -23.8 63 36.1 118 68.3 173 91.7 228 110.5 292 128.89 -22.0 64 36.9 119 68.8 174 92.1 229 110.8 294 129.3

10 -20.2 65 37.6 120 69.3 175 92.5 230 111.2 296 129.811 -18.5 66 38.3 121 69.8 176 92.8 231 111.5 298 130.312 -16.9 67 39.0 122 70.2 177 93.2 232 111.8 300 130.913 -15.3 68 39.7 123 70.7 178 93.6 233 112.1 302 131.414 -13.7 69 40.4 124 71.2 179 93.9 234 112.4 304 131.915 -12.2 70 41.0 125 71.7 180 94.3 235 112.7 306 132.416 -10.7 71 41.7 126 72.1 181 94.7 236 113.0 308 132.917 -9.2 72 42.4 127 72.6 182 95.0 237 113.3 310 133.418 -7.8 73 43.0 128 73.0 183 95.4 238 113.6 312 133.919 -6.4 74 43.7 129 73.5 184 95.8 239 113.9 314 134.420 -5.1 75 44.3 130 74.0 185 96.1 240 114.2 316 134.921 -3.8 76 45.0 131 74.4 186 96.5 241 114.5 318 135.422 -2.5 77 45.6 132 74.9 187 96.9 242 114.8 320 135.923 -1.2 78 46.3 133 75.3 188 97.2 243 115.1 322 136.424 0.0 79 46.9 134 75.8 189 97.6 244 115.4 324 136.825 1.2 80 47.5 135 76.2 190 97.9 245 115.7 326 137.326 2.4 81 48.1 136 76.6 191 98.3 246 116.0 328 137.827 3.6 82 48.7 137 77.1 192 98.6 247 116.3 330 138.328 4.8 83 49.4 138 77.5 193 99.0 248 116.6 332 138.829 5.9 84 50.0 139 78.0 194 99.3 249 116.9 334 139.230 7.0 85 50.6 140 78.4 195 99.7 250 117.2 336 139.731 8.1 86 51.2 141 78.8 196 100.0 251 117.5 338 140.232 9.2 87 51.7 142 79.3 197 100.4 252 117.8 340 140.733 10.2 88 52.3 143 79.7 198 100.7 253 118.1 342 141.134 11.3 89 52.9 144 80.1 199 101.1 254 118.3 344 141.635 12.3 90 53.5 145 80.5 200 101.4 255 118.6 346 142.136 13.3 91 54.1 146 81.0 201 101.7 256 118.9 348 142.537 14.3 92 54.6 147 81.4 202 102.1 257 119.2 350 143.038 15.3 93 55.2 148 81.8 203 102.4 258 119.5 352 143.439 16.2 94 55.8 149 82.2 204 102.8 259 119.8 354 143.940 17.2 95 56.3 150 82.6 205 103.1 260 120.1 356 144.341 18.1 96 56.9 151 83.0 206 103.4 261 120.3 358 144.842 19.1 97 57.5 152 83.4 207 103.8 262 120.6 360 145.243 20.0 98 58.0 153 83.9 208 104.1 263 120.9 362 145.744 20.9 99 58.6 154 84.3 209 104.4 264 121.2 364 146.145 21.8 100 59.1 155 84.7 210 104.8 265 121.5 366 146.646 22.6 101 59.7 156 85.1 211 105.1 266 121.8 368 147.047 23.5 102 60.3 157 85.5 212 105.4 267 122.0 370 147.548 24.4 103 60.8 158 85.9 213 105.7 268 122.3 372 147.949 25.2 104 61.3 159 86.3 214 106.1 269 122.6 374 148.350 26.1 105 61.8 160 86.7 215 106.4 270 122.9 376 148.851 26.9 106 62.4 161 87.1 216 106.7 271 123.1 378 149.252 27.7 107 62.9 162 87.5 217 107.0 272 123.4 380 149.653 28.5 108 63.4 163 87.9 218 107.4 273 123.7 54 29.3 109 63.9 164 88.3 219 107.7 274 124.0

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4.5.22 Slide Valve Error (Microcomputer)

A slide valve error will be generated if the feedback potentiometermeasures a value below -10% or above 110% for 45 seconds. Thealarm will also trigger if the oil pump is running with the compressoroff and the slide reading does not fall below 8% within 45 seconds.

When this alarm occurs, the compressor will be locke doff and thealarm light turned on. Check for proper operation and calibration ofthe potentiometer. Clear the alarm by pressing RESET.

4.5.23 Liquid Line Mod Motor Error (Microcomputer)

A mod motor error will be generated if the feedback potentiometermeasures a value that is more than 8% away from the target valuefor 45 seconds. This indicates that there is a problem with the mod

motor or feedback potentiometer reading. When this alarm occurs,the compressor will be locked off and the alarm light turned on.Clear the alarm by pressing RESET.

4.5.24 Compressor Starter Error (Microcomputer)

The microcomputer monitors the compressor starter failure con-tacts with a digital input (#5). If these contacts open at any time(digital input turns on), the compressor will be locked off on a

compressor starter error. The alarm light will also be turned on.Resolve the problem and press RESET.

4.5.25 Oil Pump Starter Error (Microcomputer)

The microcomputer monitors the oil pump starter with two digitalinputs (#687). If the oil pump overload relay opens, the oil pumpstarter error is triggered. This error is also triggered if the oil pumpauxiliary switch does not close (digital input 7 turns off) within 3

seconds of a pump start command. If this alarm occurs, the com-pressor will be locked off and the alarm light turned on. Clear thealarm by pressing RESET.

4.5.26 Chilled Water Reset (Optional)

If desired, the chilled water temperature can be raised automati-cally by a 0-5 VDC analog signal provided by an external control-ler. The reset signal must be between 0 VDC and 5 VDC, with 0VDC being no reset and 5 VDC being maximum reset. The maxi-mum temperature reset (increase) desired must be stored in CWRMAX setpoint B. For example, to raise the chilled water setpoint

from 44 F to 50 F (6.0 difference) with a 5 VDC input, a 6.0 is storedin CWR MAX setpoint B.

CAUTION: The voltage input must not exceed 5.0 VDC. Shieldedcable should be used for the signal wires with the shield connectedto ground only at one end.

4.5.27 Demand Limiting Input (Optional)

If demand limiting is desired, a 0 to 5 volt DC signal must be sup-plied to the Demand Limit terminals shown on the wiring diagram.The ground lead of the signal should be connected to GroundTerminal and the positive lead should be connected to the De-mand Limit Terminal.

Supplying 0 volts will have no limiting effect, and 5 volts will havemaximum limiting. The Demand Limit setpoint is used to determinethe maximum amount of limiting the voltage supplied to DemandLimit analog input will have. If the Demand Limit setpoint is set to0.0, there will be no limiting, and if set to 10.0, there will be maxi-mum limiting. The Demand Limit setpoint can be set anywherebetween 0.0 10.0 depending on the amount of Demand Limit de-sired.

The Demand Limit works by automatically lowering the HOLD andUNLOAD amp limits for the compressors.

This does not change the amp limit setpoints. The micro-computer takes the signal supplied to the Demand Limit analoginput, the value held in the Demand Limit setpoint, and the amplimit setpoints to calculate the amount of limiting to take place. Tocalculate the value for the Demand Limit setpoint for a desiredDemand Limiting current with 5 volts supplied to Demand Limitanalog input, use the following equation:

((Amp Limit (B)-Desired Limit Current)/Amp Limit setpoint (B)) x 10

This Demand Limiting will only unload compressors. It will not turnthem off.

CAUTION: Do not feed in a voltage higher than 5.0 VDC. Shieldedcable should be used for the 5 volt signal with the shield connectedto ground only at one end.

4.5.28 Suction Pressure Load Limiting

If the suction pressure gets close to the low pressure limit, themicrocomputer performs load limiting to reduce the possibility of alow pressure trip. When suction pressure drops below the low

pressure limit plus 4 psig, the compressor will not be allowed toload. If suction pressure drops below the low pressure limit plus 2psig, the compressor will unload until suction pressure rises.

21

4.5.29 Unit Schedule of Operation (Optional)

If a seven day time schedule of unit operation is desired, theinternal real time clock of the microcomputer can be used. Whenthe SCHEDULE control point is ON, the compressor is allowed tooperate. The following procedure is used to modify the operatingschedule.

1. Perform the authorization procedure (See 4.4.4).2. Press MENU key.3. Use Up and Down to select CONTROL POINTS.4. Press ENTER.5. Use Up and Down to select SCHEDULE control point.6. Use to display the first schedule. The standard display

screen would show:CP 17 SCHEDULE GRP:1 SCH:1 0000 2400 DAYS: *** ALLDAYS ***

This indicates that control point 17 named SCHEDULE iscontrolled by schedule group (GRP) #1. The first schedule(SCH:1) turns on at 0000 hours and off at 2400 hours (militarytime) every day of the week. Thus it is on all the time.

7. To change this schedule, press ENTER. The cursor will flashover the turn-on time.

8. Use the number keys (0-9) to enter the revised turn- on timeusing military format.

9. Press ENTER. The cursor will move over to the turn-off time.10.Use the number keys to enter the turn-off time in

military format.11.Press ENTER. The cursor will move to DAYS

during which this schedule is active.12.To change the days for this schedule, press one or

more of the following number keys: 0 - Clear all

current days; 1 - Sunday(S); 2 - Monday(M);3 - Tuesday(T); 4 - Wednesday(W); 5 - Thursday(R);6 - Friday(F); 7 - Saturday(A); 8 - *** ALL DAYS ***.

13. Press ENTER. The revised schedule number is now stored.14. To add another schedule, press the right arrow key

and repeat steps 7-13.15. To delete a schedule, clear all of the days by

pressing 0 at Step 12.The schedule group turns on when any of the individual sched-ules turns on. The turn-on time does not have to be earlier thanthe turn off time. Schedules turn on by time and day, but turn offby time alone. For example, a schedule from 1900 to 0700Saturdays would turn on at 7:00 PM Saturday (time and day) andturn off at 7:00 AM Sunday (time only).

Example: If a unit is to operate at all times except between thehours of 1:00 AM and 6:00 AM, the following schedules would beentered:CP 17 SCHEDULE GRP:1 SCH:1 0000 0100 DAYS: *** ALLDAYS ***CP 17 SCHEDULE GRP:1 SCH:2 0600 2400 DAYS: *** ALLDAYS ***

Another example: A typical building may require cooling from6:00 AM to 7:00 PM Monday - Friday and from 7:00 AM - 3:00 PMon Saturdays. The schedules would be entered as follows:CP 17 SCHEDULE GRP:1 SCH:1 0600 1900 DAYS: MTWRFCP 17 SCHEDULE GRP:1 SCH:2 0700 1500 DAYS: A

5. MAINTENANCE

5.1 GENERAL

As with all mechanical equipment, a program of regular inspection,cleaning and preventive maintenance by trained personnel willcontribute greatly to the long satisfactory service life of this product.Some of this care can easily be provided by owner personnel.

However, a Dunham-Bush authorized service mechanic shouldinspect the unit at least annually and evaluate unit performance.

5.2 PERIODIC INSPECTION

Read essential temperatures and pressures periodically to seethat they indicate normal operation. It is a good idea to record thesereadings on a log sheet.

See sample, Section 5.9. If any abnormal operation is observed, tryto determine cause and remedy it. See Troubleshooting Guide,Section 5.8.

5.3 MONTHLY INSPECTION

Check cooling tower water treatment system. Wipe down externalsurfaces of unit. Shut unit down, open main disconnect, inspectcontrol panel, checking for loose wires, burned contacts, signs ofoverheated wires, etc. Restart unit and check performance of con-trols. Put compressor in manual control and time rate of loading

and unloading. Adjust needle valves as necessary to get load andunload time of 40±20 sec., then return to automatic control. Checksight glasses for proper refrigerant charge level. See Charging,Section 5.6.

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5.4 WATER SIDE CLEANING OF VESSELS

See Section 1.4.3 Condensing Water TreatmentThe effects of fouling of the cooler or condenser heat transfer sur-faces can be detected by recording full load performance data onthe log sheet. The best measure of performance of cooler and con-denser is approach, which is the difference between leaving watertemperature and saturated refrigerant temperature at the pressurein the vessel. At full load, read cooler and condenser pressures onthe computer. Then use Table 5 to find saturated temp. for each.Read leaving chilled water temperature on the computer. Readleaving condenser water temperature with field installed thermom-eter. Then calculate approaches as follows:

Condenser Approach = T sat condenser - T lvg cond. waterCooler Approach = T lvg chilled water - T sat cooler

If the approach for either vessel increases by more than 2°F abovethe approach recorded at clean conditions, the tubes should becleaned. It is generally advisable to clean the water side surfacesat least annually and more often if severely foul water is

used. This cleaning can be done chemically or physically. Inchemical cleaning, a caustic solution is pumped through the heatexchanger, which attacks dirt, slime and mineral deposits andflushes then away. Chemicals can be recommended by watertreatment specialists, but it is important to rinse the systemthoroughly after cleaning to remove the chemicals before theyattack the metal surfaces.

Vessel tubes may be physically cleaned by first draining thewater, then removing the heads and brushing each tube individu-ally with a tube cleaning brush until clean. For best results,always remove both heads before cleaning the tubes. Replacethe heads, being careful to properly position gaskets, and refillthe system with water.

Head gaskets need not be renewed after each head disassem-bly operation. Gaskets should and must be renewed if they arephysically disfigured or otherwise deteriorated. (New gaskets areavailable from the factory. See Repair Parts List.). INSPECTCAREFULLY.

5.5 ELECTRICAL MALFUNCTION

The unit has two devices designed to protect the compressor motorfrom electrical malfunctions: motor overload relay and undervoltagerelay (optional).

If the undervoltage relay trips, it is a sign of trouble in incomingpower. If it trips again after resetting, call your electric utility to inves-tigate the problem. If the

customer-supplied fuses or motor overload relay trips, this is a signof possible motor trouble. DO NOT reset and try to run compressoragain. Call authorized service representative to check for motortrouble. Resetting these safety devices and repeated starting couldturn a minor motor problem into a costly major motor burnout.

5.6 CHARGING

5.6.1 Refrigerant Charge

The WCOX unit is given a complete charge of refrigerant at thefactory. All standard units use refrigerant R22 and the amount nec-essary to charge the unit can be found in the physical specifica-tions, Table 1.

If the unit must be charged on the jobsite, it should be done by aqualified refrigeration mechanic.

In order to check proper refrigerant charge, check condenser drainline sightglass (Figure 4, Item 3) at full load during unit operation. Ifbubbles are visible in sightglass, unit is undercharged.

Refrigerant should be added through the charging valve on thecooler feed line until the condenser drain sightglass clears. Sightglass should be clear at all operating conditions. When operatingat full load, the cooler tube bundle (visible through sightglass oncooler shell) should be covered. At light load, tubes may be visible.To add refrigerant, connect a refrigerant vessel to the liquid linecharging valve under the cooler. Purge the air from the tube withrefrigerant gas before connecting. With the unit running, open therefrigerant vessel liquid connection slightly. If the refrigerant ves-sel is warmer than the cooler, refrigerant will flow from the vesselinto the unit.

5.6.2 Oil Charge

The proper oil charge is in the unit as supplied from the factory. If forsome reason, the compressor runs low on oil, the microcomputerwill shut off the motor on a low oil pressure alarm before any dam-age is done. In the event of a low oil shutdown, call a D/B authorizedservice agent to correct the problem. DO NOT ADD OIL TO THESYSTEM.

The upper sightglass in the condenser sump should never indi-cate an oil level.

NOTE: Only CPI ISO150 (CP-4214) oil may be used in this pack-age. Use of other oil is not approved by Dunham-Bush, and couldresult in compressor failure.

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5.7 TROUBLESHOOTING

POSSIBLE CAUSES

1. Main power off.

2. No control power.

3. Undervoltage relay open.

4. Flow switch open.

5. Customer control off.

6. Compressor switch open.

7. Microcomputer shutdown,not reset.

1. Cooling not required.

2. Computer’s time delay active.

3. Undervoltage relay open.

4. Flow Switch Open.

5. Compressor switch open.

6. Burned out signal light.

7. Wiring problem.

1. Insufficient refrigerant charge

2. Bypass valve closed.

PROBLEMS

Unit will not start.

Compressor will not startwhen reset button is pushed.

Check lights: None

High seal oil temperature

INDICATION

No voltage on unit.

Control switch on, only highvoltage present.

Pilot light on relay off.

Pumps off, no flow.

Unit control analog input is 0.0.

Switch off.

Compressor control point indi-cates LOFF.

Cooler leaving water temp.less than 2°F above setpoint.

Control point indicates COFF.

See 4 above.

See 5 above.

See 6 above.

Check voltage across light.

Other indications not satisfied.

Condenser refrigerant sightglass bare.

High seal oil temperatureindicator light on.

CORRECTIVE ACTION

Check main disconnect switchand main line fuses.

Check control transformer fus-ing or customer supplied source.

Check for power supply prob-lems (low voltage, phase imbal-ance). Whencorrected, press reset button.

Start pumps, check flow switch.

Close contact.

Turn switch on.

Check alarm status.Correctproblem. Press reset button.

Apply load.

Wait 15 minutes max.

See 4 above.

See 5 above.

See 6 above.

Check signal light bulbs.

Check wiring against drawing.

Add refrigerant per 5.6.1.

Adjust valve

2. Bypass valve closed

24

PROBLEMS

High motor temperature

Low suction pressure

High discharge pressure

Low oil pressure

Freeze warning

Improper capacity control

POSSIBLE CAUSES

1. Motor windings failing.

1. Inadequate feed to cooler

2. Inadequate refrigerantcharge

3. Fouling of water side ofcooler

4. Inadequate chilled waterflow

1. Fouling of water side ofcondenser.

1. Low oil level in compressor

1. Operating setpoint too low

2. Load changing too rapidly.

1. Compressor loads/unloadstoo fast or slow.

2. Ramp rate incorrect

INDICATION

HMT light on.

Low suction pressure indica-tion on computer and light on.

Same

Same

Same

High discharge pressureindication on computer andlight on.

Oil low in sight glass oncompressor

Freeze light on. Indication oncomputer.

Same

Observe amps while manuallyloading and unloading.

See 4.5.6.

CORRECTIVE ACTION

Check megohms. Reset by hold-ing HMT reset button for 5 sec-onds.

Check to see that liquid line ballvalve is open.

See information on charging inSection 5.7.

At high load, check cooler ap-proach. (See 5.4.) If approach ismore than 2 F above cleanvalue, fouling is probably thetrouble. Clean tube bundle. See5.4.

Measure pressure drop acrossvessel and determine gpm fromfig. 4. If gpm is low, check chilledwater pump, valves and strain-ers.

At high load, check differencebetween saturated R22 temp.and leaving water temp. If 1-2 Fabove start-up conditions, re-move heads and clean tubes.

Low oil level in compressorsight glass is acceptable.

Check leaving water setpoint onmicrocomputer.

Load on package must drop atreasonable rate for automaticcontrol to work properly.

Adjust needle valves for 40 sec-ond load/unload rate when load-ing/unloading with microcom-puter in manual control mode.

See 4.5.6.

25

5.7 TROUBLESHOOTING - (contd)

5.8 Sample Log Sheet FORM #NAS3003

WCOX Pressure/Temperature Log SERIAL #____________________ MODEL #___________________ DATE _____________________

COMPRESSOR SLIDE VALVE POSITION ____% ____% ____% ____% ____%

A SUCTION TEMPERATURE

B SATURATED SUCTION TEMPERATURE

C SEAL OIL TEMPERATURE

D DISCHARGE TEMPERATURE

E DISCHARGE PRESSURE

F SATURATED DISCHARGE TEMPERATURE

DISCHARGE SUPERHEAT (F-D)

G OIL & DISCHARGE PRESSURE

NET OIL PRESSURE (G-E)

H CONDENSER LIQUID OUT TEMPERATURE

I CONDENSER LIQUID OUT PRESSURE SATURATED PSI °

PSI °

PSI °

PSI °

PSI °

NET SUBCOOLING (H-I)

J COOLER WATER IN F

K COOLER WATER OUT F

COOLER APPROACH (B-K)

L CONDENSER WATER IN F

M CONDENSER WATER OUT F

CONDENSER APPROACH (F-M)

GPM CONDENSER

GPM COOLER

PRESSURE DROP ACROSS OIL FILTERS MAX. 5#

COMPRESSOR VOLTAGE AND AMPERAGE

26

WCOX SERVICE PARTS LIST

CONDENSER PARTS

Condenser Model Description Part # 30163 34163 37163 39163 43163

Tube 012659A1 482 580 697 772 920 * Gasket, 1 Pass

Inlet/Outlet 008907B8 2

008907B9 2 008907D1 2 008907D2 2 008907D3 2

* Gasket, 2 Pass I/O, Return

008907A8, B8 1, 1

008907A9, B9 1, 1 008907C1, D1 1, 1 008907C2, D2 1, 1 008907C3, D3 1, 1

*Recommended Spare Parts

COOLER PARTS

Description Part # 30163 34163 37163 39163 43163 Tube 012659A1 232 278 336 372 448

* Gasket, 1 Pass Inlet/Outlet

008907B8 2

008907B9 2 008907D1 2 008907D2 2 008907D3 2

* Gasket, 2 Pass Return

008907A8, B8 1, 1

008907A9, B9 1, 1 008907C1, D1 1, 1 008907C2, D2 1, 1 008907C3, D3 1, 1 No. Tubes 012657 223 271 333 366 446

* Gasket, 3 Pass Inlet/Outlet

01760A4 2

01760A5 2 01760A6 2 01760A7 2 01760A8 2

27

PIPING PARTS

Description Part # WCOX056-107Oil Return Line: 1.25 - 12 x 7/8" ODS Rotalock Valve Filter Drier Block 5/8" ODS Angle Valve 5/8" ODS Check Valve 5/8" ODS Sight Glass Jet Pump 1/2" MPT x 5/8" FLR Angle Valve

GA422 BLK42 VAL367 VAL389 003555A2 PMP102 300P135

3 1 1 1 1 1 1

Pumped Oil System: * Oil Pump * Motor, 3 HP 208-230/46/3/60 * Oil Strainer Cartridge * ISO150 Synthetic Oil 1/2" ODS Check Valve 3/8" MPT x 1/2" FLR Angle Valve 2 1/8" ODS Valve Filter Drier Cores 3/8" FLR x 3/8" MPT Angle Valve 1 1/4" Ball Valve

013092A1 013094A1 013881A1 013882A1 VAL388 200P135 009843A4 BLK 100P135 013046A2

1 1 1 1 1 1 1 2 2 1

Suction Discharge Lines: 8" Butterfly Valve 8" 300LB Flange Gasket 6" Flange Gasket 10" 150LB Gasket 10" Swing Check Valve

IRVAL1107T8 GKT380 GKT248 IRGKT600T1 013879A2

1 3 1 3 1

Load/Unload Piping: 1/4" MPT x 3/8" FLR Angle Valve 3/8" ODS Solenoid Valve * Solenoid Valve Coil 3/8" ODS Angle Valve

50MP135 VAL488 COL122T40 006381B2

1 2 2 3

Control Piping: 1" 3-way Valve 300 PSI Condenser Relief Valve 255 PSI Cooler Relief Valve 3/8" FLR x 3/8" MPT Angle Valve

VAL581 VAL556 013125A1 100P135

1 1 1 4

Hot Gas Bypass Option: 1 1/8" ODS Solenoid Valve 1 1/8" ODS Ball Valve * Solenoid Valve Coil

005184A1 002733A7 COL119T1

1 1

Hot Gas Unload Starter Option: Solenoid Valve

VAL774

1

ELECTRICAL: Common Voltage (All 60 Hz Units)

External Electric: * Oil Sump Heater * Discharge Temperature Sensor * Refrigerant Level Transducer Mod Motor Transformer

HTR71 013673A1 013674A1 010310A1

3 1 1 1

28

PIPING PARTS (CON'T.) Description Part # WCOX056-107Control Panel: NL25-4 Microcomputer Board Digital I/O Board Analog Input Board 40 VA 115/230-12 Transformer * 4 Amp Fuse * Ribbon Cable Ribbon Cable Connector 12 VAC Power Cable WCOX Micro Chip 0-200 PSIG Pressure Transducer 0-500 PSIG Pressure Transducer .22 MFD Snubber Leaving Water Thermister Sensor Sump & Seal Oil Thermister Sensor 5.1 VDC Zener Diode 10,000 OHM Resistor 15 A Fuse OPDT Control Relay 3PDT Control Relay 2 Pole Lighted Switch Red Light 250 OHM Resistor

009635A3 009636A5 009637A1 009638A2 013362A1 009836A1 009643A1 009644A1 009827T1 009510A5 009510A6 013571A1 009509A3 009509A4 013054A1 003008A1 FUS48 000879A1 008525A1 012866A1 012867A1 003008B7

1 1 2 1 2

6 Ft. 5 1 1 1 2

10 1 2 4 3 4 2 1 2 1 1

29

P. O. Box 20000, Harrisonburg, VA 22801PH 540-434-0711, FAX 540-434-2448

Form 6186