HWSC-D

Features• Rotary screw compressors

• Efficient performance• Smooth, quiet operation

• Reduced maintenance expense

Form No. 5303C

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Water-Cooled Chillerswith Rotary Screw Compressors50 to 300 Tons

SCREW COMPRESSORS REPRESENT GREATER VALUETHROUGH EXPANDING TECHNOLOGY

The HWSC Outperforms Recips andCentrifugalsToday's highly-competitive construction market forcesengineers, contractors and equipment manufacturers tocontinually improve the value of their products andservices. D-B's HWSC screw compressor chillers arean excellent example of innovative design, backed by30 years of air conditioning experience and thoroughtesting. Neither reciprocating nor centrifugalcompressors can match the screw compressor on afirst cost versus performance analysis.

Lower First CostD-B HWSC chillers are available in a compact packageup to 300 tons allowing easier installation and smallerequipment rooms. The multiple compressor, staggeredstart design, combined with modulating capacitycontrol, eliminates the need for expensive starters andhot gas bypass. The two-pole compressor motor allowsa .91 power factor without the use of correctioncapacitors. Optional single-source power minimizeselectrical installation and full factory run testingguarantees trouble free start-up. And, best of all,redundancy is built in above 75 tons, in contrast tocentrifugal designs which require tremendouspremiums for compressor back-up.

Higher Operating EfficienciesDue to efficiencies of screw compressors, the HWSCchillers offer significant energy savings. Full loadefficiencies of approximately .80 KW/ton are offered.However, the major savings occur during part loadoperation due to the modulating compressor control,preventing overcooling associated with stepped control,and the multiple compressor design which allowsunnecessary compressors to be cycled off. In fact, fourcompressor HWSC units allow capacity reduction downto 7.5% of design without requiring energy wasting, hotgas bypass. Due to part load savings, the HWSC offerslower energy costs than centrifugal chillers if asubstantial amount of part load operation is required.

Greater ReliabilityScrew compressors are inherently reliable since theyuse approximately 1/10 the moving parts ofreciprocating compressors. Reliability is furtherenhanced by utilizing suction gas to cool the motor andactual compressor pressure differential to force feed oilto the bearings and rotors. This eliminatesmaintenance-prone oil pumps and liquid injectioncooling. The compressor is further protected by a fullset of safety controls. Another outstanding attribute isthe screw compressor's tremendous resistance todamage from liquid slugging which is the major causeof reciprocating compressor failures. This sluggingresistance is the result of the suction cooled motor,superheating the refrigerant, the structural integrity ofthe rotors as compared to pistons, and the modulating

capacity control allowing superior thermal expansionvalve operation.

Unsurpassed Redundancy and ServiceabilityIn addition to the reliable design, the HWSC offers moreback-up than any reciprocating or centrifugal chiller onthe market today. Up to four compressors are offered,each with its own refrigeration system. In the unlikelyevent of a compressor failure, no other refrigerantcircuit is affected. This basically means up to 75%back-up is provided on all components including mostcontrols. Add to this a design which allows easyreplacement of compressors and heat exchangers(none are welded in place) and easy maintenancerequirements which are virtually identical to therequirements of reciprocating chillers.

The reliability and redundancy offered by the HWSC isideal for critical installations.

Quiet OperationThis compressor is, quite simply, the quietestcompressor in its size range. The inherently balancedcompression results in a compressor vibrationamplitude of only 7 microns. The compressor noisealso occurs at a higher vibration frequency allowingeffective attenuation by the optional compressoracoustical enclosure and by equipment room walls.The screw compressor is quieter than competitivescrew compressors due to the ribbed, double wallconstruction and the greater amount of rotor surfacearea.

Infinitely Modulating Capacity ControlPrecise control of leaving water temperature ismaintained by the screw compressor modulating slidevalve, in combination with a microprocessor basedsupply water temperature controller.

Leaving water temperature variations are controlled toless than 1/2(F accuracy; five times the accuracy ofreciprocating compressors. Maintaining constantsupply water temperature allows much closer control ofcomfort conditions.

Reduced Maintenance ExpenseScrew compressor chiller maintenance is almost non-existent due to the reliability in design and, whenrequired, is virtually identical to the requirements ofreciprocating compressors. Centrifugal chillers, incontrast, require very specialized and proprietarymaintenance. Most centrifugal chillers also utilizenegative pressure refrigeration systems which involvea significant expense in lost refrigerant due to periodicpurging of contaminants. When all of these extracentrifugal maintenance expenses are taken intoaccount, it becomes apparent that the HWSC offers alower total operating cost than any competitivealternative.

2

ARI CERTIFICATION

ARI CERTIFICATION PROGRAM

The performance of DB Water-Cooled Rotary ScrewWater Chillers has been certified by the AirConditioning and Refrigeration Institute (ARI).

Full load ratings, part load ratings, and water pressuredrop data are regularly tested under this program andare certified in accordance with ARI Standard 550/590-98. This provides an independent, third partyverification of water chiller performance with alaboratory-grade performance test utilizinginstrumentation which has calibration traced to theNational Bureau of Standards.

The ARI Seal of Certification on each and every D-BHWSC chiller shows our commitment to quality and toour customer's peace of mind. You know you'll get theindustry's standard for efficiency and reliability whenyou purchase a D-B water chiller.

Computer Performance RatingsD-B HWSC Water-Cooled Rotary Screw Water Chillersare available from 50 to 300 tons. A chiller may becustom matched to specific building requirements byyour D-B Sales Representative utilizing the HWSCComputer Selection Program which has ratings whichare certified in acordance with ARI Standard 550/590-98. Data which can be provided to you will include:�� Chiller Capacity�� KW Input�� Evaporator and Condenser Water Pressure

Drop�� Part-Load Performance

Contact your local D-B Sales Representative to discusswhat Custom Solutions D-B can offer to solve yourchiller selection questions.

PHYSICAL DATAMODELS HWSC-50 THRU 150

Model HWSC 50 60 75 100 110 120 135 150

Nominal Capacity - Tons 45 55 64 89 99 109 121 130

SEMI-HERMETIC SCREW TYPE COMPRESSORSNo. of Compressors 1 1 1 2 2 2 2 2Nominal Size (HP) 50 60 75 (2)50 50-60 (2)60 60-75 (2)75Oil Charge (Oz.) 202 236 236 (2)202 (1)202(1)236 (2)236 (2)236 (2)236Crankcase Heater (Watts) 200 200 200 (2)200 (2)200 (2)200 (2)200 (2)200

COOLERStorage Capacity (Gal.) 6.25 9.4 11.1 17.6 25.4 25.4 29.4 29.4Diameter x Length 860 1060 1160 1360 12102 12102 14102 14102

CONDENSERSNo. of Condensers 1 1 1 2 2 2 2 2Diameter x Length 1279 1279 1279 1279 1279 1279 1279 1279

UNITRefrigerant Charge - R22 (Lbs.) 70 73 100 150 170 175 190 200Net Weight (Lbs.) 2500 2900 3600 4700 5150 6200 7000 7500

MODELS HWSC-180 THRU 300Model HWSC 180 210 225 240 255 270 300Nominal Capacity - Tons 165 184 193 218 226 236 256

SEMI-HERMETIC SCREW TYPE COMPRESSORSNo. of Compressors 3 3 3 4 4 4 4Nominal Size (HP) (3)60 (1)60(2)75 (3)75 (4)60 (3)60(1)75 (2)60(2)75 (4)75Oil Charge (Oz.) (3)236 (3)236 (3)236 (4)236 (4)236 (4)236 (4)236Crankcase Heater (Watts) (3)200 (3)200 (3)200 (4)200 (4)200 (4)200 (4)200

COOLERStorage Capacity (Gal.) 60.5 60.5 60.5 67.7 67.7 67.7 67.7Diameter x Length 18122 18122 18122 20122 20122 20122 20122

CONDENSERSNo. of Condensers 3 3 3 4 4 4 4Diameter x Length 1279 1279 1279 1279 1279 1279 1279

UNITRefrigerant Charge - R22 (Lbs.) 216 248 264 288 304 320 352Net Weight (Lbs.) 10500 11500 12000 13000 13500 14000 14500

4

HWSC ELECTRICAL DATA (50 - 150)(Consult Dunham-Bush for 208-230 Volt Data)

Model 60 Hz of CircuitHWSC 3 Ph. Start Ampacity

Volts Type Minimum

COMPRESSORS RECOMMENDED

RATED LOAD AMPS LOCKED ROTOR AMPSMOTOR NO. MOTOR NO. Wire Max.

Size FuseSize 1 2 1 2

50460 XL 64 - 422 - 80 4 125

460 Y-D 64 - 141 - 80 4 125

60460 XL 78 - 485 - 98 3 150

460 Y-D 78 - 162 - 98 3 150

75460 XL 95 - 539 - 119 1 175

460 Y-D 95 - 180 - 119 1 175

100460 XL 64 64 422 422 144 0 175

460 Y-D 64 64 141 141 144 0 175

110460 XL 78 64 485 422 162 00 200

460 Y-D 78 64 162 141 162 00 200

120460 XL 78 78 485 485 176 00 225

460 Y-D 78 78 162 162 176 00 225

135460 XL 95 78 539 485 197 000 250

460 Y-D 95 78 180 162 197 000 250

150 460 XL 95 95 539 539 214 0000 300

46O Y-D 95 95 180 180 214 0000 300

HWSC ELECTRICAL DATA (180-300)

ModelHWSC

Volts Type Ampacity Size Size60 HZ of3 PH. Unit

COMPRESSORS Minimum Minimum MaximumCircuit Wire Fuse

RATED LOAD AMPS LOCKED ROTOR AMPSMOTOR NO. MOTOR NO.

1 2 3 4 1 2 3 4 Cir.1 Cir.1 Cir.1

180460 XL 78 78 78 - 485 485 485 - 254 300 300

460 Y-D 78 78 78 - 162 162 162 - 254 300 300

210460 XL 95 95 78 - 539 539 485 - 292 350 350

460 Y-D 95 95 78 - 180 180 162 - 292 350 350

225460 XL 95 95 95 - 539 539 539 - 309 350 400

460 Y-D 95 95 95 - 180 180 180 - 309 350 400

240460 XL 78 78 78 78 485 485 485 485 332 400 400

460 Y-D 78 78 78 78 162 162 162 162 332 400 400

255460 XL 95 78 78 78 539 485 485 485 353 500 400

460 Y-D 95 78 78 78 180 162 162 162 353 500 400

270460 XL 95 95 78 78 539 539 485 485 370 500 450

460 Y-D 95 95 78 78 180 180 162 162 370 500 450

300460 XL 95 95 95 95 539 539 539 539 404 (2)300 450

460 Y-D 95 95 95 95 180 180 180 180 404 (2)300 450

NOTES:1. XL: Across the line; Y-D: Star-Delta.2. RLA (Rated Load Amps) rated.3. Starting current for normal Y-D start is shown. In certain compressor failure modes, Y-D inrush can be as high as XL inrush.4. Wire Size Amps equal 125% of the rated load amps for the largest motor in the circuit plus 100% of the rated load amps for all other motors

in the circuit, per N.E.C.5. Based on copper conductors with 75(C. insulation, per N.E.C. Table 310-16.6. Maximum fuse size is based on 225% of the rated load amps for the largest motor in the circuit plus 100% of the rated load amps for all other

motors in the circuit. This is the largest fuse allowed per N.E.C. A smaller fuse is often recommended based on unit application and ambienttemperature.

VOLTAGE TOLERANCES:1) 208 volt: min. 187, max. 2292) 230 volt: min. 207, max. 2533) 460 volt: min. 414, max. 506

5

SPECIFICATION GUIDELINES

GeneralFurnish and install as shown on plans, a D-B Model HWSCWater Cooled Packaged Chiller.

The unit is to be completely factory assembled and wired in asingle package complete with screw compressor(s), cooler,condenser, starting control and safety and operating controls.It is to be given a complete factory operating and controlsequence test under load conditions and is to be shipped withfull operating charge of R-22 and full oil charge.

The unit shall be built in accordance with all applicable nationaland local codes including the ANSI B31.5 Refrigerant PipingCode; the National Electrical Code and applicable ASME codefor Unfired Pressure Vessels. The unit shall also include ETLcertification and labeling.

The unit shall be furnished for operation on a ___V, three phase___ Hertz power supply and to have an EER rating not to beless than ___.

Dimensions and CapacityThe unit shall be furnished as shown on capacity schedules anddrawings. Unit performance shall be ARI certified inaccordance with ARI Standard 550/590-98. A chiller whichdoes not include ARI certification is not acceptable.

ConstructionThe unit shall be constructed from painted, heavy gaugegalvanized steel (sizes 50 to 150), and steel "C" channel (sizes180 to 300), with built-in skid and lifting holes. Componentsshall be arranged for easy access and all compressors andheat exchangers shall be easily removed and replaced.

EvaporatorCooler shall be direct expansion, shell and tube type. The shellshall be fabricated from seamless carbon steel pipe, with finnedcopper tubes and tube sheets of heavy gauge carbon steel.Models HWSC50-100 shall have welded heads and tubesbrazed to the tubesheets. Models HWSC110-300 shall haveremovable heads and tubes roller-expanded into thetubesheets. The cooler shall be insulated with not less than3/4" of closed cell foamed plastic. Cooler shall be designed,constructed and inspected to comply with current ASME codefor unfired pressure vessels. Shell side (water) design workingpressure is to be 200 PSIG and tube side (refrigerant) designworking pressure is to be 250 PSIG.

The coolers are to be circuited so that each compressor isconnected to an independent refrigerant circuit.

Condensers Condensers shall be shell and tube type, with water in thetubes, and sized for full refrigerant pump down capacity. Thecondensers shall have removable heads on both ends for tubecleaning and servicing. A subcooler shall be provided as anintegral part of the condensers. The condensers shall be builtin accordance with ASME code for unfired pressure vessels andstamped accordingly. Design working pressures shall be 150PSIG on the water side and 350 PSIG on the refrigerant side.The condensers shall be leak tested at working pressure andinclude relief valves and purge valves.

CompressorThe overall compressor design shall include a suction cooledmotor, integral lubrication system utilizing compressor pressuredifferential, and semi-hermetic design.

The rotors are to be precision made from ductile cast iron. Male rotors are to have 5 lobes and female rotors 6 lobes.

The casing is to be constructed from a high strength ironcasting, having reinforced double wall construction, to providea rigid structure and minimize transmission of noise.

Four roller bearings are to be used to support the rotors and bedesigned to absorb the radial loads. Four ball bearings are alsorequired to absorb the axial thrust and to position the rotors.

An 80 mesh reinforced stainless steel strainer shall be providedat the suction of the compressor.

A two-pole hermetic squirrel cage motor is to be supplied. Adust-proof terminal box, located in an accessible location on thecompressor, shall contain all connection terminals.

An oil separator which is an integral part of the compressorcompartment is to be furnished. An impingement plate is to bedirectly connected to the discharge end of the compressor. Aneasily removable 150 mesh stainless steel oil strainer is to beinstalled in the compressor body.

An electric crankcase oil heater shall be provided to maintainthe proper oil temperature when the system is not in operation.

Capacity ControlAn infinitely variable capacity control system that is capable ofexactly matching the demand requirement of the system is to besupplied. A microprocessor based controller shall modulate acompressor slide valve, in response to supply watertemperature and maintain water temperature within 1/2(F ofsetpoint. This system is to provide precise and stable controlof supply water temperature over the complete range ofoperating conditions. It shall be capable of a system capacitycontrol range from 100% to ____% at specified conditions.(See page 3)

Refrigerant CircuitEach compressor shall be provided with an independentrefrigerant circuit for maximum standby protection. Parallelcompressors are not acceptable due to oil control problems andcross contamination. The numbers of compressors andrefrigerant circuits shall be as follows:

HWSC-D 50-75 1 CompressorHWSC-D 100-150 2 CompressorsHWSC-D 180-225 3 CompressorsHWSC-D 240-300 4 Compressors

Each refrigerant circuit shall include expansion valve, sightglass, moisture indicator, solenoid valve, replaceable core filterdrier, liquid line shut off valves, charging and gaugeconnections and discharge line check valve.

7

SPECIFICATION GUIDELINES (CONTINUED)

Control Center UNIT OPTIONSThe Control Center is to be a fully enclosed steel cabinet with Alarm Historyhinged access doors. Dual compartments, separating safety � Three most recent alarms; low pressure, highand operating controls from the power controls, are to be pressure, freeze protection, sensor failure, externalprovided. Controls shall include: shutdown� High pressure cutout, manual reset Remote Monitoring� Low pressure cutout, manual reset � RS232 communication link for remote monitoring� Compressor, solid state, thermal sensing overloads, manual direct to PC or by optional telephone modem

reset Short Circuit Protection - Individual compressor (fusing)� High refrigerant discharge temperature, manual reset (circuit breakers) shall be provided.� Low water temperature freeze protection, manual reset� Protection against low voltage, phase loss and phase Star-Delta Open Transition Start - Provide reduced inrush

reversal (auto-reset) starting for each compressor as scheduled.� Power terminal block for single or dual source power� Compressor starter including current sensing overload Hot Gas Bypass - provide a hot gas bypass valve and hot gas

protection solenoid valve on last circuit off to permit operation of the� Microprocessor based controller and factory installed sensor system down to ___% (see page 3) of full load capacity.

including integral anti-cycle protection� Complete labeling of all control components Pressure Gauges - Provide factory mounted and piped suction� Numbered terminal strips for easier wire tracing and discharge pressure gauges for each refrigerant circuit.

Microcomputer Control (NC25-4) - Provide microcomputer toinclude the following: Control Circuit Transformer - Provide a factory mounted andControl wired control circuit transformer for the 115 volt control circuit.� Staging and loading� Lead/lag and load balance Pressure Sensing Freezestat - A pressure sensing freeze-stat� Ramp up at start-up shall be provided, in addition to the temperature sensing freeze-� Alarm output and customer interlocks stat, on each circuit complete with a two minute time delay to� Compressor current limit prevent nuisance trips. (Standard with micro option).

Protection� Low and high pressure, freeze up Indicator Lights - provide externally visible indicator lights that� Sensor failure signal control circuit operation, individual compressor operation� High oil and motor temperature and safety failure for each refrigerant circuit.� Anti-recycle timing

Readouts Water Flow Switch - provide a flow switch, for field installation, � Analog Inputs: amps, leaving water temperatures, to shut down the unit on loss of chilled water flow.

evaporator and condenser pressure� Digital Inputs: compressor contactor, flow switch Vibration Isolators - Provide (rubber-in-shear) (spring

(optional), customer on/off vibration) isolators, for field installation, under unit baseSetpoints members. � Leaving water temperature, freeze up temperature,

high and low pressure, amp limit, ramp up Acoustical Enclosure - Provide a sound attenuating cabinet

Each gauge is supplied with its own manual shut-off valve.

for the compressor(s), constructed of 18 gauge galvanized steeland completely insulated with 1", 3 lb. density sound absorbinginsulation.

101 Burgess Road, Harrisonburg, Virginia 22801Phone: 540-434-0711 FAX: 540-434-4595

www.dunham-bush.comForm No. 5303C June 2000