Screw Type Air-Cooled Packaged Chillers ACWC-SC
Contents
1. 12 OVERLOAD HEATER STARTER CONTACTOR COMPRESSOR cupi moron 5 71 prsi z DOOR LATCWimO SOLENOID FAN CYCLING PRESSURE CONTROL Lue 1 8 MOTOR CONDENSER FAN res CIRCUIT BREAKER FAN MOTOR POWER FUSE TRANSFORMER PHASE LOSS MONITOR TERI 2 TERMINAL BOARD MAIN POWER TERMINAL BOARD CONDENSER TERMINAL BOARD CUSTOMER WIRING zn 71 viMi 2 vouT 058 MONITOR NOTES 1 M4 FCP7 8 3 16 ARE NOT REQUIRED 2193C 2 FOR 1 14 BEE CONTROL CIRCUIT WIRING DIAGRAM FIELD FACTORY WIRING 16 TYPICAL POWER WIRING STAR DELTA START USE COPPER CONDUCTORS ONLY ACWC 160 200 SC REFER TO UNIT SPEC PLATE FOR VOLTAGE TO CONTROL CIRCUIT 11 1 ra jmd dd 1 114 fs Be a T bero T AI Jorriowan 1 men wine wine MER SUPPLIED cure NOTES LES FCPS O ARE NOT REQUIRED 180 CI CM CONTROL CIRCUIT WIRING DASRAA nuo ws Factor USE COPPER CONDUCTORS ONLY REFER TO UNIT SPEC PL2. 7OMINO2 TEE se 310409 3191 01105 505534409 M31V3H 26 SHalv3H z e c82 11102412 TOULNOD 2 182 531426 55344 00 8 12 38 OL 310W3H 5 HOLIMS 072 OL 15 TYPICAL POWER WIRING ACROSS THE LINE START USE COPPER CONDUCTORS ONLY ACWC 160 200 SC oo PLM2 Luz OPTIONAL TO COMTWOL CIRCUIT LMI Le den TO CONTROL CIRCUIT Y cis LEGEND OLMi 9 OVERLOAD HEATER STARTER C6 CONTACTOR COMPRESSOR 13 19 CONTACTOR CONDENSER FAN 1 3 COMPRESSOR MOTOR DLSI 2 0009 LATCHING SOLENOID FCPi 10 CYCLING PRESSURE CONTROL GROUNDING 106 DETAIL FOR ONE TERMINAL BLOCK MODELS LOSS MONITOR NOTES FCPS 810 ARE WOT REQUIRED OK 18056 2 FOR 1 14 SEE CONTROL CIRCUIT WIRING DIAGRAM WIRING FACTORY WIRING ACWC 215 SC gerioNAL PLMi OPTIONAL OPTIONAL lPLu2 VLM2 OPTIONAL TO CONTROL CIRCUIT
3. 998 j 39 19 v9 mast bel M52 MOTA e WHOILO eu 281 mw 1028 MAT 035012 NOILISNVHS 035012 9NILHVIS 917349 391 soy 19134 15 Y17320 391 NOILISNYHI N3dO NOILISNVBI N3dO 14 4 9NIOVIS 3 9o TYPICAL CONTROL WIRING ACWC 215 SC G 5 HOLINOM 807 110 2 18 441 100 X201 INIL MOLOVINOD NOILISNYML AYT30 en WOLOVINOD ABWONODAS 1 HOS sil M31V3M 234 Linoura 9 9 89 1 160 W31Y3H 13234 uU 7041402 38 65384 W31vaH EN SH31V3H AMVONODS 1 734 16 068 LLL 3 134 Ht W31V3H IH2d Su3l4YlS 931Y3H 21 1 on ivisOWN3Hl INZIONV MOT 11 H dioN310s svo 10 5 341334638 2 viz 30038 012 9 IZ NOLS31ONd Lita annows v 136 2
4. 4314915 341 100 4901 AV T30 HOLOVINOD NOILISNYHI Av 13d INIL MOLOVINOD NOILISNYYL W31V3H 3SVOXNYH2 31v3H 1119419 AVISOWMdHL W31v3H 3A 393H JOHiNOO 38583844 H3iV3H H3Al393N H31V3H 935 AV 13H S1H91 10114 BilV3M 55384 AUYAIUd 84314913 SH31v3H A1V1SONH3Hl l1Nil8MY MOT 910 3108 5 9 LOH NOI12310M4 ANYA ANNOYS SNVJ 10H1NO2 3unividdWil 1 3 8 QION3105 GN30VO IN 8 130 O 12 4 08 08 TVNIWH34 01502 18 08 aal 71044405 2 INIL 21 0194 NI N201 A13 ANIL 4317081N02 LVASONYIHL MOT LYLSONYSHL M32N3n03 Lv160Wd3H L 5411940 HILIME 1 08 36Y9X4NYM2 N907183LNI CERTI M31SYm HOLIMS NI X201 AV I3H 9WI5YLS MOLINOM 5501 Al34vs 110 1510 3233484 380553 4 MOT 663 MOT 1341 3sfnivH3dW3l MOT 7041405 38055384 31n00W 31918
5. Open suction and discharge valves to pressure gauges if supplied Check rotation of ali fan motors motors and bearings lubricated Start auxiliary equipment pumps fans etc Is crankcase heater operating Check high pressure control Check oil temperature safety switch Check and adjust low pressure or temperature freeze control Check and adjust operating thermostat Check and adjust low pressure operating control Check and adjust expansion valve superheat Check and adjust capacity control thermostat OPERATING DATA CHILLER Voltage L 1 L 3 Pressure Gauge Readings a Suction b Discharge psig High pressure switch setting Cut In gt psig _ psig Out Checked Setting Low Pressure Switch Setting Cut in psig psig Out Checked Setting Yes No Low Pressure Freeze Control Cutin Cut Out Oil Temperature Safety Switch Cut Out If Star Delta start time delay is seconds Temperature of air entering condenser ___ F Temperature of air leaving condenser F Temperature of chilled water entering chiller Temperature of water chilled leaving chiller F Chilled water pressure entering chiller psig Chilled water pressure leaving chiller lt lt psig YES NO
6. 03174415 LOM BUY 2 1 WIA N3HM 1 SNY4 10 1 02 2 1 409 hiis due ere 2 1 30 MOSN3S SLOVANOD M3 Od 335 3univu3dN3 1 bi 9 19 1109 YOLOVINGD 303 9 934834 Ob T zi 380238 2 9 sor az 03114408 LON amp 148 MIHA a 55384 0 w 1824 LIYA NGA Y IONOS enu 136 vor 622 60512 tas ONIMIM 101294 IYNINYAL 3OO38 21 OL se 161161 92 H3WOISDO ONVOS 7VNIWH31 931 01 SIMIM 3114418 IHY 42 02 01 N3HM 1041400 91 LINN 11 131410 u31VM NI X901 21 691 NI 0319207 1 21 ONITDAD Av330 8 601 M3YIOMINOO AlIOVdYO LYLGOWMSHI S310N 3MnLvU34N31 MO 339N30035 LYLSOW 3HI 511028 MOSS3HdNMOD HILIMS 010011 4 0 108 1105 es 36Y2XNVMD AVIU 39031N AV TaN se 31SYW HOLIMS NI 201 Av 138 5 te 72081402 Al1I2VdY2 AV T3N ONIOVIS fes MOLINOM 5501 41335 3niviidWil 10 323344 MOT 1341 71081N09 3UnSS3Nd MOT es
7. Maximum ambient air to condenser is 115 F 60 Hertz operation 2 Maximum allowable cooler water pressure is 150 PSIG 3 Maximum allowable water temperature to cooler is 75 F 4 Units must not have leaving water temperatures of 42 F or lower unless used with a glycol solution 5 Unit must be allowed to pumpdown at the end of each operating cycle except on safety control shutdown KEY TO WIRING DIAGRAM INDEXING SYSTEM The wiring diagrams and sequence instructions on the following pages have been devised to simplify the understanding and tracing of circuit theory The following key shows how the indexing system can be used 12 Line number on wiring diagram 12 Line number in text R5 Component identification symbol text Relay 5 Normally open contact line number location Normally closed contact line number location Holding coil line number location A Note number See Note Number 3 The coil for the first contact shown on this line reading from left to right can be found on line 44 the holding coil for the second contact can be found on line 74 The contacts for the hoiding coil shown on this line can be found on lines 66 23 and 54 The contact on line 23 is normally closed This is the number which identifies the line of wiring shown at the left SEQUENCE OF OPERATION and 15 63 provide an interlock for the water pump starter s MODELS ACWC 160 To 200 SC either contact
8. must be present at all time to prevent motor injury The length of time a bearing can run without having grease added or replaced will depend upon the operating conditions Under normal operating conditions the motor bearings should be lubricated at 2000 hour operating intervals The lubricant should be from a clean closed container and should anti friction type bearing grease free from solid fillers or other harmful ingredients Lubricant should have a safe operating temperature of 2000 F The air inlet of the condenser coil should be kept clean through a regular preventative maintenance program COMPRESSOR 1 OIL LEVEL The oil level in the compressor s shouid be checked periodically with the compressor either running or stopped If the oil level is below one half 7 the sight glass must be added Oil should be added only with the compressor shut off To do so turn the return water thermostat T1 to a higher temperature setting and wait for the unit to pumpdown and shutoff Place the system ON OFF switch in the OFF position Close the line valve in the discharge line between compressor and condenser Refrigerant pressure inside of the compressor will now be approximately 80 to 90 PSIG The low pressure cut out setting is 35 PSIG but the residual discharge pressure upstream of the discharge check valve will equalize back into the suction side after the compressor stops Locate the discharge pressure por
9. 01105 1N195 M31v34 Mayya H3TTIH2 431v3H 289 10H1N02 M33v348 1119812 199 NY4 H38N3QNO2 042 CERE YO13YLNOJ 9 19 QN3931 SNILHVIS 911390 391 18 NOILISNYHI N340 11 TYPICAL CONTROL WIRING ACWC 215 SC LINDAI 1NYH390443H s 94 1119513 H31Y3H GGG 0000 fs spa e 2 az 92 13 v vl 8 zi or 5310 s7109 12v1N03 ON 5 1830 0 43 14405 NAHM 188 1510 022 221 119134 235 WNOILdO M071134 WNOIAL40 MONE A gt 9 21 D 881 ro NOILISNVHi 435015 4In28l2 4140919 NOILISNVHI N3dO ONILYVLS Y11730 4915 NOILdO 1138 44 8 LON SLINIWD NHV7V NO NOILdO 804 1VOIdAL 12 ON INIT 310N ON 3NI1 SLOVLNOD 4 A11VNHON 8 1 09 ASII ON 3NI1 51094 00 036012 AT1VWBON 314408 YAMO V C ON BOD CEER s GG 44 TYPICAL CONTROL WIRING ACWC 215 SC
10. R14 R16 or R18 62 will close any time a The following sequence of operation is typical for the ACWC 160 to compressor is ranning 200 SC see Pages 10 and 11 for typical wiring diagram Refer to the Set the staging thermostat T1 to the design range of operation e g wiring diagram furnished with unit for specific information 54 F return water Set the capacity control thermostat T3 to the Control Identification Symbol design range of operation e g 44 F supply water Circuit Line Number Place the four 4 control circuit switches SW1 SW4 in the position thus energizing the balance of the control circuit The Important Note 1 system will be in the Time In mode for five minutes before any The compressor crankcase heater must be energized and remain i compressor will start active for a minimum fo 24 hours prior to unit start up PRELIMINARY SEQUENCE STAGE 1 LOADING Place control circuit ON OFF switches SW1 thru SW4 in the Upon demand for cooling the first step of the staging thermostat OFF position and set the staging thermostat T1 to its highest T1 will close energizing relay TD10 63 and staging relay R1 temperature 62 closing R1 contacts 7 4 22 8 5 25 and 9 6 16 If the Activate the 115 volt electrical service to terminals 2 and 4 1 and safety controls and switches are closed the control circuit 16 for 3 onterminal board TER5
11. y 1 4119819 1 2885 H10 1410 NOILISNYHI 138012 NOILISNvHI 340 93114405 03 ONILYVLS 91734 594 8 BAL 2 Iso 912 1407 1 9 m lt 2 2 li 1 9712 6 X idi 8 oy eni 9 Lii TTT 22 1 N1S2 93s 06 CNOILdO 1138 03114405 LON O 11951 NO NOILdO HO4 WOldAL 1 1 1 T 102812 WNW 2 D 802 102 Q i y9 a SII Wr xis 820 169 Q 850 4 7 y INIT 310N RZ 69 5 ON S19 LNOD NIJO ATIVMYON INIT 5109140 ATIvRUON 1 21 5 Xov v INIT 6102 1 09 AGI 2 5102 SLOVLNOD ON 10 TYPICAL CONTROL WIRING ACWC 160 THRU 200 SC 5 1 LINDY M39N3n03 amp f HOSS3HdMO2 lt ddd lt lt q o oog il 2 4 1 04 o9 48 9 vs ee 24
12. 18 opens to prevent contactor C2 from energizing The S1 N O normally open auxiliary contact 17 closes energizing C1 17 The C1 power contacts close applying power to the motor The C1 auxiliary contact closes locking C1 in the energized position The compressor operates in the star mode until TD1 times out 5 seconds at which time TD1 contact 16B opens de energizing S1 The S1 N C contact 18 closes energizing contactor C2 18 closing C2 power contacts thereby completing the Delta wiring configuration C2 N C auxiliary contact 16A opens preventing S1 from energizing until the next starting sequence There is an instant of time the open transition between the opening of S1 power contacts and the closing of C2 power contacts in which power across the motor windings is interrupted 2 1NvH39IH43H 505535490 4444 lt NINII TYPICAL CONTROL WIRING ACWC 160 THRU 200 SC UN 1102319 H31v3H 310N LINDHID 44 225383 8 119134 vH 021714408 MIHM NOILISNYHL 035013 unus ONILYVLS Vilad 391 ez vQ 43 av TIVI3d 52
13. 2 119 10 9 66096 44 iv 9 Sr vy 0 Li 43 14405 N3HM bay Lt HS S 9 6 M 621 2361 13 b d S S gt E Ea NOILISNYYL 035012 NOI LISNVHL N3dO TVNOI 9NILHVIS VIT30 591 ame 622 gt 1 LINDHIS NOSS3NdMOD TYPICAL CONTROL WIRING ACWC 215 SC LINDH 4 444 44 99 100813 44 az 49 81 44 94 8 09 64 es 9 IMS vu 9 Ly Te vile 2 553 4 2 aw 592 v vu 40 14314406 N3HA rimi 71 v 40 i ANE JP NO C RM 112 918 pion 842 44 v4 W1 2 NOUS wNOHd0 91 19 92 9 zzy 6 To Dri 24 1105815 30552484905 9723 k 210 AS MOTTBA 892 213 152 9 1 70 03 14406 G3NIM 35 b 8 oli Ap ot LN 2 a 488 982
14. ATE FOR VOLTAGE ACWC 215 SC DOOR LATCHING SOLENOID FAM CYCLIMB PRESSURE CONTROL Luo 8 7 CONDENSER FAN OVERLOAD HEATER STARTER s EX cos cwri s compnesson moron 1223 reaa encu nearen comrnesson cicur BREAKER FAN NOTES 1 84 MB FEP 7 0 15 18 ARE ROT On 255 8 R FOR CI CM BE CONTROL CIRCUIT buanan me 17 ELECTRICAL DATA 60 HZ TOTAL UNIT CHARACTERISTICS 4 COMPRESSORS CONDENSER FANS Suggested L Wire 512 187 253 400 700 414 506 0960 350 208 230 187 253 339 468 500 600 500 460 388 450 500 700 300 501 501 700 900 900 222 222 300 0000 0000 420 500 eo ATL Across The Line 1208 230 voltage requires two field wiring supplies circuits Minimum circuit ampacity is N E C Section 430 24 Use time delay dual element fuses only Suggested fuse sizes based on N E C Section 440 22 Wire size based on copper conductors with 75 C insulation per N E C Table 4310 16 5Single point power terminals NOTE Maximum inrush amps is L R A of lag compressor R L A of all other compressors F L A of all fans Lag Compressor 75 H P
15. MODEL ACWC SC APRVICE MANUAL Screw Type AIR COOLED PACKAGED CHILLERS INSTALLATION OPERATION amp MAINTENANCE INSTRUCTIONS TABLE OF CONTENTS DESCRIPTION PAGE NO Inspection amp 2 2 cer a 2 Location 8 e eis paci ere en RR nr gedeagece 2 2 Ghillor pte px Se Par E en mede 2 i ciae Me REPRE EL E I T 2 amp 3 22 c v eae ere pex yx dx eer vo Ke rre e M ERAT EE PROS UR pr a du 3 Slide Valve Unloading System 4 Low AR enn 5 eR visi aile man Mie e E Drain ec 5 Unit Operating Limitations 5 Sequence of Operation 6 amp 7 Models ACWC 160SC Thru 200SC Sequence Operation I Ber TRO id 8 amp 9 Model ACWC 215SC Control Dia GRAM re prt o S prb 10 amp 11 Models ACWC 160SC Thru 200SC Control Wing 4 rechnen tre rne teta
16. arge pressure whenever UL 1 opens to permit flow to the oil return low Load Unload gt Oil Pressure Slide Valve Screw Rotor pressure line The slide valve will move to the right unloading whenever UL 2 opens the oil supply high pressure line since the force of the oil exceeds that of the discharge gas The temperature controller sends a series of power energizing pulses to the appropriate solenoid to adjust to load conditions The further the supply water temperature is from the controller set point the longer is the duration of the pulses The series of pulses will continue until the controller is satisfied As the water temperature approaches the set point the pulses become quite brief to prevent overshooting the set point This method of compressor unloading in conjunction with supply water sensing minimizes action reaction lag time and overshoot resulting in an exceptionally precise and stable control of supply water temperature Hydraulic Piston Oil Oil Return Supply The following table lists solenoid vaive position for all three operating modes uts Unloading Close Open Close DO LOW AMBIENT OPERATION Due to the wide range of applications it is sometimes necessary to operate the Air Cooled Packaged Water Chillers at ambients below summer conditions Without proper control when ambients drop below 60 F the pressure differential between the condenser an
17. ce with the directions in the maintenance instruction page 3 n CAUTION The discharge line valve must be open before starting the compres Sor Liquid line valves must also be open for sustained operation compressors are solid mounted on isopads therefore compressor hold down bolts must not be loosened Loosening these bolts will cause excessive vibration of the compressor and may result in refrigerant line breakage Prior to start up check all compressor hold down bolts for tightness MAINTENANCE CONDENSER Units equipped with belt drive fans have inherently protected motors Fan belts fan bearings and motor bearings require periodic maintenance as follows 1 Fan Belts After two 2 weeks operation the belts will have nearly reached their permanent stretch therefore each belt should be checked again and proper adjustments made To maintain good fan and motor operation the belt tension should be checked at three 3 month intervals 2 Fan Bearings Each fan shaft is provided with ball bearings of the relubricatable type Each bearing is provided with grease fittings accessible through the individual motor access panels It is recommended the bearings be greased by adding 4 to 5 shots with ahand gun The suggested greasing interval is indicated ona Sticker attached to the unit 3 Motor Bearings Each motor is equipped with ball bearings Ball bearings consume a very small amount of lubricant but enough
18. d the evaporator is below the level to insure proper thermal expansion valve operation As a result the unit may cycle on low pressure control with the possibility of evaporator freezing Three types of system control are available allowing the units to operate at the ambients indicated FAN CYCLING MEDIUM AMBIENT CONTROL TO 30 F STANDARD EQUIPMENT FACTORY INSTALLED A fan cycling control is standard on all Air Cooled Packaged Water Chillers to provide proper operating head pressures in ambient conditions to 30 F This is an automatic operation in which the condenser fans are cycled on and off as required in response to head pressure With two compressors running three fans are cycled in sequence on five fan units four fans on six fan units and five fans on seven fan units With one compressor running all but the lead fan are cycled in sequence in response to head pressure This arrangement provides positive start up control down to 30 F by delaying the condenser fan operation until a predetermined head pressure is obtained GRAVITY Discharge DAMPERS LOW AMBIENT CONTROL TO 0 F OPTIONAL EQUIPMENT FACTORY INSTALLED All condenser fans are equipped with gravity dampers mounted on the fan discharge to minimize the effect of prevailing winds and to prevent convection drafts up through the condenser coil in still air All compressors are enclosed in individual insulated housings An auxiliary heater is includ
19. e chiller circuit has been cleared of refrigerant and the suction pressure is approximately 35 PSIG Low pressure control LP4 contact will then open de energizing compressor contactors C7 80 and C8 81 stopping compressor 4 and de energizing relays R14 and R23 Relay R14 N C normally closed contact 2 8 85 energizes lock out timer TD8 preventing compressor 4 re start for five minutes Relay R23 energizes compressor 4 crankcase heater s Staging thermostat T1 also de energizes relay R10 opening contact 9 6 releasing compressor 3 from continuous full load operation Relay R10 contacts 8 2 and 7 1 close allowing capacity control thermostat T3 to operate capacity control solenoid valves UL1 3 and UL2 3 as required STAGE 3 PUMPDOWN A further decrease in return water temperature will de energize staging relay R3 closing liquid line solenoid SOL2 When chiller circuit 2 low side has pumped out low pressure control LP2 opens stopping compressor 2 and de energizing relays R12 and R21 Relay R12 N C contact 2 9 51 energizes lock out timer TD6 preventing compressor 2 re start for five minutes Relay R21 energizes compressor 2 crankcase heater s Staging thermostat T1 also de energizes relay R9 opening contact 9 6 releasing compressor 1 from continuous full load operation Relay R9 contacts 8 2 and 7 1 close allowing the capacity control thermostat to operate capaci
20. e the leads of the phase loss monitor for this will allow the compressor to run backwards causing severe damage and WILL VOID THE COMPRESSOR WARRANTEE Start up the chilled water pump The water flow is confirmed when the water flow switch completes an electrical circuit across terminals 12 89 and 13 91 of terminal board TERS Terminals 14 92 and 15 94 provide an interlock for the water pump starter s either contact R11 R12 R13 or R14 95 will close any timea compressor is running Setthe staging thermostat T1 to the design range of operation e g 54 F return water Set the capacity control thermostat T3 to the design range of operation e g 44 F supply water Place the five contro circuit switches SW1 thru SW5 ih the ON position thus energizing the balance of the control circuit The system will be in the time In mode for five minutes before any compressor will start STAGE 1 LOADING Upon demand for cooling the first step of the staging thermostat T1 will close energizing relay TD15 94 and staging relay R1 93 closing R1 contacts 7 4 32 8 5 35 and 9 6 26 If the safety controls and switches are closed the control circuit 26 for compressor 1 and liquid line solenoid 5011 35 will energize allowing the compressor to start Relay R20 30 contact 9 6 39 closes energizing fan contactor C13 39 bringing power to the line side of fan cycling pressure contro
21. ed to supplement the standard crankcase heater the temperature within the compressor compartment is thermostatically controlled The standard condenser fan cycling package operating in con junction with the discharge dampers will maintain suitable head pressure down to 0 F ambient A 90 second time delay relay provides an electrical bypass around the low pressure freezestat to prevent nuisance trip out during cold start up ACWC SC CONTROL SETTINGS PRESSURE ACTUATED LEGEND FACTORY SETTING High Pressure Control Manual Reset Pumpdown Control Auto Reset Fan Cycling Pressure Control Adjustabte Low Pressure Freeze Control Manual Reset Chiller Water Cycling Thermostat Adjustable Oil Temperature Safety Control Adjustabie Manual Reset TEMPERATURE ACTUATED LEGEND FACTORY SETTING Chiller Low Water Temperature Thermostat T DialSetAt Chiller Heater Thermostat Included With Cut In Wr Non Adjustable CBH1 Heater Cut Out 45 F Capacity Control Thermostat Adj Mode Control Position Dial Set At 300 PISG 365 PSIG 55 PSIG 35 PSIG HP 1 Cut In HP2 amp HP3 Cut Out PD1 Cut In Cut Out Cut In PSIG 280 PD2 amp PD3 2 Fan Cell FCP 1 FCP2 295 3 Fan Cell FCP 1 260 FCP2 275 290 4 Fan Cell FCP 1 FCP 2 275 FCP 3 285 FCP 4 LPF 1 Cut Out LPF 2 amp LPF 3 OTS 1 OTS 2 Cut Out 240 F 3 UNIT OPERATING LIMITATIONS 1
22. ens removing the circulating pump starter interlock SAFETY CONTROLS Each refrigerant circuit is protected by seven standard safety controls and one optional safety control 1 High Pressure 2 Low Pressure Freeze LPF High Discharge Temperature OTS Low Oil Temperature LOT Compressor Solid State Module CSTM Low Water Temperature T2 Low Pressure LP 8 Compressor Starter Overloads OLH optional If any of these devices should open due to abnormal conditions the compressor will automatically stop All controls must be manually reset except Low Oil Temper ature LOT Low Pressure LP and Compressor Solid State Module CSTM which resets itself after a two minute bleed down period The compressor motor wind ings are also equipped with a thermal protector automatic reset which is not shown on the wiring diagram STAR DELTA STARTING OPEN TRANSITION The following starting sequence applies to the power wiring diagrams on Page 17 as well as the control wiring on Pages 10 thru 15 Detail A Page 10 is typical of all screw compressor star delta start and will be used as an example Staging relay R1 contact 9 6 16 closes energizing star contactor S1 16B and the 5 second transition timer TD1 16A The S1 power contacts close tying the center legs of the motor windings together into the star configuration The 51 N C normally closed auxiliary contact
23. essor 3 and liquid line solenoid SOL3 70 wili energize allowing the compressor to start Relay R22 66 contact 7 1 8 opens de energizing crankcase heater s Contact 9 6 74 closes energizing fan contactor C14 74 bringing powerto the lineside of fan cycling pressure controls FCP7 thru FCP12 see power wiring diagrams Fan motor 4 will start as soon as the head pressure reaches the cut in setting of FCP7 Relay R13 65 contact 8 5 69 closes energizing TD11 68 This will force compressor 3 to run for five minutes Compressor 2 cannot be started until TD11 times out Time delay relay TD16 96 contact C NC 71 holds compressor 3 in an unloaded condition for 30 seconds When TD16 times out it will energize R7 72 closing contacts 9 6 108 and 7 4 113 This allows the capacity control thermostat to energize solenoid valve UL1 3 108 loading the compressor or to energize solenoid valve UL2 3 113 unloading the compressor STAGE 3 LOADING Upon a further increase in return water temperature the third step of the staging thermostat T1 will close If lock in timer TD11 and lock out timer TD6 66 have timed out relays R3 97 R9 99 and TD17 98 will be energized Relay R3 contacts 9 6 45 8 5 and 7 4 50 close If the safety controls and switches are closed the control circuit 45 for compressor 2 and liquid line solenoid SOL2 53 will energize aliowing
24. for compressor 4 and liquid line solenoid SOL4 87 will energize allowing the compres sor to start Relay R23 83 energizes opening contact 7 1 7 de energizing compressor 4 crankcase heater s Relay R14 82 contact 8 5 86 closes energizing TD12 This will force compressor 4 to run for five minutes Relay R10 contact 9 6 107 closes energizing solenoid valve UL1 3 thus locking compressor 3 in the fully loaded position Relay R10 contacts 8 2 108 and 7 1 113 open to disconnect the capacity control thermostat T3 from compressor 3 capacity control solenoid valves _ Time delay relay TD18 101 contact C NC 88 holds compressor 4 in an unloaded condition for 30 seconds When TD18 times out it will energize relay R8 89 closing contacts 9 6 110 and 7 4 115 Thie allowe tho capacity control thermostat T3 to anargiza solenoid valve UL1 4 110 loading the compressor or to energize solenoid UL2 4 115 unloading the compressor Compressors 1 and 3 are fully loaded Compressors 2 and 4 are being capacity modulated PUMPDOWN SEQUENCE STAGE 4 PUMPDOWN A decrease in return water temperature will cause the fourth step of the staging thermostat T1 to open thereby de energzing staging relay R4 opening contacts 8 5 9 6 and 7 4 Liquid line solenoid SOL4 will de energize stopping the flow of refrigerant to chiller circuit 4 The compressor will continue to run until th
25. inues to run until chiller circuit 1 pressure is down to the low pressure Control LP1 set point The LP1 contact opens de energizing compressor contac tors C1 171 C2 18 and fan contactor C13 21 stopping compressor 1 and the remaining fan motor s Relay R14 N C contact 8 2 23 energizes lock out timer TD4 preventing compressor 1 re start for five minutes relay R14 contact 7 4 62 opens removing the circulating pump starter interlock Relay R19 de energizes closing contacts 7 1 3 energizing compressor 1 crankcase heater s SAFETY CONTROLS Each refrigerant circuit is protected by seven standard safety controls and one optional safety control 1 High Pressure HP Low Pressure Freeze LPF High Discharge Temperature OTS Low Oil Temperature LOT Compressor Solid State Module CSTM Low Water Temperature T2 Low Pressure LP 8 Compressor Starter Overloads OLH Optional If any of these devices should open due to abnormal conditions the compressor wil automatically stop All controls must be manually reset except Low Oil Temperature LOT Low Pressure LP and Compressor Solid State Module CSTM which resets itself after a two minute bleed down period The compressor motor windings are also equipped with a thermal protector automatic reset which is not shown on the wiring diagram WN SEQUENCE OF OPERATION MODEL ACWC 215 SC The following sequence of
26. lowing the compressor to start Relay R20 36 contact 7 1 5 opens de energizing crankcase heater s Contact 9 6 44 closes energizing fan contactor C14 44 bringing power to the line side of the balance of the fan cycling pressure controls see power wiring diagrams Fan motor 3 will start as soon as the head pressure reaches the cut in setting of FCP3 Relay R16 35 contact 8 5 39 closes energizing TD8 38 This will force compressor 2 to run for five minutes Compressor 3 cannot be started until TD8 times out Time delay relay TD11 65 contact C NC 41 holds compressor 2 in an unloaded condition for 30 seconds When TD1 1 times out it will energize R5 42 closing contacts 9 6 72 and 7 4 75 This allows the capacity control thermostat T3 to energize solenoid valve UL1 2 72 loading the compressor or to energize solenoid valve UL2 2 75 unloading the compressor STAGE 3 LOADING Upon a further increase in return water temperature the third step of the staging thermostat T1 will close If the lock outtimer TD6 and the lock in timer TD8 66 have timed out relays R3 66 R7 68 and TD12 67 will be energized Relay R3 contacts 9 6 48 7 4 53 and 8 5 56 close If the safety controls and switches are closed the control circuit 48 for compressor 3 and liquid line solenoid SOL3 56 will energize allowing the compressor to start Relay R21 52 energi
27. ls FCP1 thru FCP6 see Power Wiring Wiring Diagram on Pages 16 and 17 Fan motor 1 will start as soon as the head pressure reaches the cut in setting of FCP1 NOTE ALL FAN MOTORS ARE CONTROLLED BY THEIR OWN FAN CYCLING CONTROL AND WILL CUT IN AT DIFFERENT HEAD PRESSURES Relay R20 contact 7 1 3 opens de energizing compressor 1 crankcase heater s Relay R11 29 contact 8 5 34 closes energizing TD9 33 This will force compressor 1 to run for five minutes COMPRESSOR 3 Stage 2 CANNOT BE STARTED UNTIL TD9 TIMES OUT Time delay relay TD15 94 contact C NC 36 holds the compressor in an unloaded condition for 30 seconds When relay TD15 times out it will energize relay R5 37 closing contacts 9 6 106 and 7 4 112 This allows the capacity control thermostat T3 to energize solenoid valve UL1 1 106 loading the compressor or to energize 8 solenoid valve UL2 1 112 unloading the compressor Relay R11 29 contact 7 4 95 closes which completes the interlock circuit for the water circulating pump STAGING 2 LOADING Upon a further increase in return water temperature the second step of the staging thermostat T1 will close If the lock in timer TD9 95 and lock out timer TD7 95 have timed out relays R2 95 and TD16 96 will be energized closing R2 contacts 9 6 62 7 4 67 and 8 5 70 If the safety controls and switches are closed the control circuit 62 for compr
28. n open de energizing compressor contactors C5 49 and C6 50 stopping compressor 3 and de energizing relays R18 and R21 Relay R18 N C normally closed contact 2 8 54 energizes lock out timer TD6 preventing compressor 3 re start for five minutes Relay R21 energizes the compressor crankcase heater s Staging thermostat T1 also de energizes relay R7 opening contact 9 6 releasing compressor 1 from continuous full load operation Relay R7 contacts 8 2 and 7 1 close allowing the capacity control thermostat T3 to operate capacity control solenoid valves UL1 1 and UL2 1 as required STAGE 2 PUMPDOWN A further decrease in return water temperature will de energize staging relay R2 closing liquid line solenoid SOL2 When chiller circuit 2 has pumped out low pressure control LP2 opens stopping compressor 2 and de energizing relays R16 and R20 Relay R16 N C contact 8 2 38 energizes lock out timer TD5 preventing compressor 2 re start for five minutes Relay R20 36 energizes compressor 2 crankcase heater s and also de energizes fan contactor C14 44 stopping the fan motor s servicing the two circuit condenser slab STAGE 1 PUMPDOWN Step 1 of the staging thermostat T1 will open when the return water temperature is reduced to the set point This de energizes staging relay R1 closing liquid line solenoid 5011 stopping refrigerant flow to chiller circuit 1 Compressor 1 cont
29. omplete drainage of chiller and piping system The chilled water piping should be insulated to reduce heat pickup and to prevent condensation If the system is for year round operation or if it will not be drained in the winter the chilled water piping should be protected against freezing by electric heating cable or other suitable means Upon completion of chiller piping start the system water pump and purge air from the system Air purging should be done from the high points in the water circuit Purging of the chiller barrel may be accomplished through the vent pipe located on the top of the chiller compartment Failureto purge air from the water circuit will result in inadequate water flow and may causethe unit to cutout on low water flow freeze protection START UP Refer to start test and check list included with this manual Check all electrical and mechanical connections for shipping looseness and tighten all screws on electrical terminals Activate the 115 volt chiller and crankcase heater circuit 24 hours prior to unit start up Rotate each fan priorto start up Fansshould turn freely Check belt tension and pulley alignment After two 2 weeks of operation readjust belt tension to accommodate for belt stretching Check all control settings as specified in Table 1 Check the compressor oil level through the crankcase sight glass The oil level should be to the top of the glass If the level is low add oil in accordan
30. on 185SC COOLER WATER PRESSURE DROP Feet of Water 17 1 18 8 206 119 19 1 143 157 17 1 185 202 143 157 17 1 186 20 2 L 111 bias hiss 11441155 LOADING LBS m 1 2 5 6 7 8 1855 2280 1960 1630 1630 129 1960 Le ee eme Dem ero m 2158 2330 2150 2155C 129 18 Equipment Inspection Setting Unit Wiring Piping Alignment Before Start Up After Start Up START UP CHECK LIST Unit damaged on arrivai Material received agrees with shipping papers Vibration isolator used Spring isolator adjusted for equal height rubber in shear isolators are used is unit leveled by shimming Power wiring complete Control wiring complete Electric service adequate for load Power source voltage correct for motor s used Motor circuit has proper size fusetrons System wired per diagram All lead connections tight Wiring complies with local codes Piping complies with applicable codes External piping independently supported Chilled water lines insulated 70900709 mg 4D All belts adjusted and checked for tension AM pulleys checked and adjusted for proper pitch tightness and alignment Open compressor discharge service valve Open liquid valve s
31. operation is typical for the ACWC 215 SC see pages 12 to 15 for typical wiring diagram Refer to the wiring diagram furnished with unit for specific information Control Identification Symbol Circuit Line Number Important Note The compressor crankcase heater must be energized and remain active a minimum of 24 hours prior to unit start PRELIMINARY SEQUENCE Place control circuit ON OFF switches SW1 thru SW5 in the OFF position and set the staging thermostat T1 to its highest temperature Activate the 115 volt electrical service to terminals 2 and 4 1 and 3 on terminal board TERS to distribute power to the control circuit up to the control circuit switches Crankcase heater relays R20 3 R21 5 R22 8 and R23 10 are closed and are supplying power to the compressor crankcase heaters Power is also supplied to the chiller barrel heaters CBH1 17 and CBH2 20 the receiver heaters RH1 2 3 4 12 13 15 16 optional and the low ambient crankcase heaters SCH1 2 3 4 3 5 8 10 optional Close the main power disconnect switch Check to see that the red indicating lights on the phase toss monitors PLM1 and PLM2 are lit These tights must be on to indicate proper phase rotation for the compressor s If the lights are not on the main control circuit to the compressors will not be energized Reverse any two phase legs at the main Incoming power terminal block DO NOT revers
32. os 12 or de 9v 5 3LIHA val 1 242 53 38 602 5 LON St NIHA 5 03174805 LON 3HY 7739 ONY WOlldO 1H9 9 SLOVLNOD H3MOd NIVM 335912 8 12 92 NAHL 13 5109 NOLOVINOO WOJ A13A1123483U 1 OGZ 8 1 2 2 40318408 LON 3HV 449 9 245 140 Y 92 03114406 LON 51 1171 X 662 9 9 amp 2 BIZ 30238 OL 681 421021 SIAM 5 IHY 1 9 01 NIHA LIINI 11 137100 0317207 8405495 AMIL C1 21 1 1 HOSNI 48 NAOH 335 5055 347 40 S310N 431 OL s3uas 21 122 NI 3H 01 n IE JLOWaY 92 Vyrouims 01 wave x ims HOSS3HdWO MOTIJA 6 H10 mao 03 14408 088 45 6 2 ze 1 8 2 6 fend Wey l T 9155 1 yi 7 NOLO i Sr 3018 9 2 8 NOILISNYHI 035079 HOLINOM 5501 110
33. oving the unit a short distance Physical damage to the unit after acceptance is not the responsibility of the factory LOCATION amp MOUNTING Model ACWC Air Cooled Packaged Water Chillers are designed for outdoor application and may be mounted on roof or at ground level Air flow through the condenser is vertical and the unit may be located adjacent to outside of building or on roof without regard for prevailing wind direction Since these units are air cooled the flow of air to and from the condenser coil must not be impeded There must be no obstruction above the unit that would tend to deflect discharge air downward where it could be recirculated back to the inlet of the unit The required overhead air space should be a minimum of eight 8 feet Ductwork must not be applied to the fan outlets The unit must be installed with sufficient clearance for air entrance to the condenser coil and for servicing access The unit should be located no closer than four 4 feet from any wall or other obstruction Clearance must be provided at either end of the unit to permit removal of tubes from the chiller Unit must be set on a solid and level foundation On roof installations the unit should be mounted on support beams which span load bearing walls to prevent excessive vibration On ground level installations the unit should be mounted on a substantial base that will not settle A one piece concrete slab with footings extended below the frost line i
34. rse any two phase legs minutes COMPRESSOR 2 CANNOT BE STARTED UNTIL TD7 at the Main Incoming Power Terminal Block DO NOT reverse the TIMES OUT leads on the phase loss monitor for this will allow the compressor to Time delay relay TD10 63 contact C NC 26 holds the compressor run backwards causing severe damage and WILL VOID THE in an unloaded condition for 30 seconds When relay TD10 times COMPRESSOR WARRANTEE out it will energize relay R4 27 closing contacts 9 6 71 and 7 4 Neon Start up the chilled water pump The water flow is confirmed when the water flow switch completes an electrical circuit across terminals 12 58 and 13 60 of terminal board TER5 Terminals 14 61 74 This allows the capacity control thermostat T3 to energize solenoid valve UL1 1 71 loading the compressor orto energize solenoid vaive UL2 1 74 unloading the compressor Relay R14 19 contact 7 4 62 closes which completes the interlock circuit for the water circulating pump STAGE 2 LOADING Upona further increase in return water temperature the second step of the staging thermostat T1 will close If the lock out timer TD5 and the lock in timer TD7 64 have timed out relays R2 64 and TD11 65 wil be energized closing R2 contacts 9 6 32 8 5 40 and 7 4 37 If the safety controls and switches are closed the control circuit 32 for compressor 2 and liquid line solenoid SOL2 40 will energize al
35. s Rn ya RUPEE Ee sent e thee dar 12 15 Model ACWC 215SC Power Wiring Diagram eee re 16 Across The Line Start POWER Wing DIA Quant ssc secede SSE EEEF ENESE ESNEA 17 Star Delta T 18 Cooler Pressure Drop 18 Unit Loading Suspension mauu tert e e a ape ees 18 Troubleshooting Guide 19 Causes amp Prevention of 19 StarteUp Check Bist ete reme RR rmn Ra mee ar 20 co cc nee 20 BOHN HEAT TRANSFER A Gulf Western Company Danville Illinois 61832 217 446 3710 INSPECTION amp HANDLING When unit is received it should be checked for visible or concealed damage If damage has occurred it should be reported to the carrier immediately and claim filed Models ACWC 160SC thru 215SC are factory mounted on two 2 permanent angle beam carbon steel skids Eight 8 2 lifting eyes are provided in the skids to allow rigging Spreader bars must be used between rigging lines to prevent damage to the unit Rollers may be used under the skids to facilitate m
36. s recommended A space should be left between the slab and the building to prevent the transmission of sound and vibration Vibration mounts may be used for roof mounted units or other locations where noise might be objectionable WIRING A unit wiring diagram showing the required power supply character istics and all factory supplied wiring details is provided with unit Separate field supplied disconnects must be installed in the power supply and should be within the sight of the unit Separate 115 volt power source must be field supplied to provide power for control and heater circuits CHILLER PIPING Thechiller inlet return water pipe should be connected to the water connection closest to the control panel end of the unit and the outlet supply water pipe connected water Connection on tne opposite end of the cooler s A flow switch must be installed in a straight horizontal section of the chilled water piping Gauges should be installed in the piping to and from the chiller to measure the pressure drop and to insurethe proper GPM flow rate in accordance with submittal data A strainer should be installed in the piping on the inlet side of the chiller and vibration eliminators should be employed on both the inlet and outlet pipes Air vents should be iocated at all high points in the piping system Vents should be located to be accessible to servicing Drain connections should be provided at all low points to permit c
37. t adjacent to solenoid valve UL 3 see drawing below remove the cap and release the residual pressure by pushing in on the pressure port fitting itself Pump oil into this purl level 1 to tne top of tne signt glass Replace the discharge port cap Re open the discharge line valve Do not allow compressor to run with discharge valve closed Place the system ON OFF switch in the ON position Using a jumper wire make a short for five 5 seconds between terminal 4 on terminal block TERS the switched terminal of a solenoid valve feeding the circuit you have just blown e g terminal 121 on TER4 to energize SOL 1 Reset return water thermostat 1 to the operational temperature setting and allow unit to return to normal operation RECOMMENDED OIL The unit is factory charged with BOHN SR 30 refrigeration oil Do not add any other type of oil to this factory charge Do not operate compressor if oil level is below one half 12 sight glass If the oil level is below the minimum specified above and BOHN SR 30 is on hand you may drain the entire factory oil charge then refill with SUNISO 4GS refrigeration oil Thefactory BOHN oil is of the synthetic type and will not mix with SUNISO 4GS Do not attempt to operate the screw compressor with any oil other than these two specified above It is suggested that a gallon or more of BOHN SR 30 oil be obtained and kept on hand at the job site The s
38. the compressor to start Relay R21 49 energizes opening contact 7 1 5 de energizing compressor 2 crankcase heater s Relay R12 48 contact 8 5 52 closes energizing TD10 51 This will force compressor 2 to run for five minutes Compressor 4 cannot be started until TD10 times out Relay R9 contact 9 6 105 closes energizing solenoid valve UL1 1 thus locking compressor 1 in the fully loaded position Relay R9 contacts 8 2 106 and 7 1 112 open to disconnect the capacity control thermostat T3 from compressor 1 capacity control solenoid valves Time delay relay TD17 98 contact 54 holds compressor 2 in an unioaded condition for 30 seconds When TD17 times out it will energize relay R6 55 closing contacts 9 6 109 and 7 4 114 Thisallows the capacity control thermostat T3 to energize solenoid valve UL 1 2 109 loading the compressor or to energize solenoid valve UL2 2 114 unloading the compressor Compressor 1 is full loaded Compressors 2 and 3 are being capacity modulated STAGE 4 LOADING Upon a further increase in return water temperature the fourth step of the staging thermostat T1 will close If the lock in timer TD10 and the lock out timer TD8 100 have timed out relays R4 100 R10 102 and TD18 101 will be energized Relay R4 contacts 9 6 79 7 4 84 and 8 5 87 close If the safety controls and switches are closed the contro circuit 79
39. to distribute powerto the control circuit compressor No 1 and liquid line solenoid 5011 25 will energize up to the control circuit switches Crankcase heater relay contacts allowing the compressor to start Fan contactor C13 21 will also v R19 3 R20 5 and R21 7 are closed and are supplying close bringing power to the line side of fan cycling pressure power to the compressor crankcase heaters Power is also supplied controls FCP1 and FCP2 see Power Wiring Diagram Pages 16 to thechiller barrel heater CBH1 11 the receiver heaters RH1 2 and 17 Fan motor 1 will start as soon as the head pressure reaches 3 8 9 10 optional and the low ambient crankcase heaters the cut in setting of FCP1 SCH1 2 3 3 5 7 optional NOTE ALL FAN MOTORS ARE CONTROLELD BY THEIR OWN Close the main power disconnect switch Check to see that the red FAN CYCLING CONTROL AND WILL CUT IN AT indicating light on the phase loss monitor PLM1 is lit NOTE There DIFFERENT HEAD PRESSURES will be two phase loss monitors PLM1 and PLM2 on 208 230 volt Relay R19 20 contact 7 1 3 opens de energizing compressor 1 models This light must be on to indicate proper phase rotation for crankcase heater s Relay R14 19 contact 8 5 24 closes the compressor s If the light is not on the main control circuit to energizing TD7 23 This will force compressor 1 to run for five the compressors will not be energized Reve
40. ty control solenoid valves UL1 1 and UL2 1 as required STAGE 2 PUMPDOWN A further decrease in return water temperature will de energize staging relay R2 closing liquid line solenoid SOL3 When chiller circuit 3 has pumped out low pressure control LP3 opens stopping compressor 3 and de energizing relays R13 and R22 Relay R13 N C contact 2 8 68 energizes lock out timer TD7 preventing compressor 3 re start for five minutes Relay R22 energizes compressor 3 crankcase heater s and also de energizes fan contactor C14 74 stopping the fan motor s on the lag half of the condenser slab STAGE 1 PUMPDOWN Step 1 of the staging thermostat T1 will open when the return water temperature is reduced to the set point This de energizes staging relay R1 closing liquid line solenoid SOL1 stopping refrigerant flow to chiller circuit 1 Compressor 1 continues to run until chiller circuit 1 pressure is down to the low pressure control LP1 set point The LP1 contact opens de energizing compressor contac tors C1 27 and C2 28 and relay R20 stopping compressor 1 Relay R20 de energizes fan contactor C13 stopping the remaining fan motor s and also energizes compressor 1 crankcase heater s The LP1 contact also de energizes relay R11 Relay R11 N C contact 2 8 33 energizes lock out timer TD5 prevent ing compressor 1 re start for five minutes Relay R11 contact 7 4 95 op
41. ubstitution of SUNISO 4GS oil as outlined above will result in a 2 to 4 capacity loss and no reduction in input K W COMPRESSOR REPAIRS Internal Contact factory or an authorized BOHN Service Agency if a compressor malfunction is suspected COMPRESSOR REPAIRS External Proper operation of unloaded start loading and unloading is controlled by solenoid valves UL 1 UL 2 and UL 3 Any ofthesethree 3 solenoid valves may be repaired or replaced in the field as required UL 3 UL 2 HIGH PRESSURE PORT SLIDE VALVE UNLOADING SYSTEM Bonn screw compressor capacity control system for infinite modulation consists of a slide valve and hydraulic piston cylinder operator internal to the compressor plus three hydraulic solenoid valves UL 1 UL 2 amp UL 3 piped externally The slide valve forms a portion of the chamber wail in which the rotors turn thus its position with respect to the rotors determines the effective rotor length and thereby the percent of full load capacity Upon compressor start up UL 3 is opened This allows oil pressure to act upon the hydraulic piston holding it in the fully unloaded position After 30 seconds during which time full oil flow is established to all bearings surfaces UL 3 is closed Atthis point the temperature controller is free to open and close UL 1 or UL 2 in response to the supply water temperature The slide valve will move to the left loading by force of disch
42. zes opening contact 7 1 7 de energizing compressor 3 crankcase heater s Relay R18 51 contact 8 5 55 closes energizing TD9 54 This will force compressor 3 to run for five minutes Relay R7 contact 9 6 70 closes energizing solenoid valve UL1 1 thus locking compressor 1 in the fully loaded position Relay R7 contacts 8 2 71 and 7 1 74 open to disconnect the capacity control thermostat T3 from compressor 1 capacity control solenoid valves Time delay relay TD12 67 contact C NC 57 holds compressor 3 in an unloaded condition for 30 seconds When TD12 times out it will energize relay R6 58 closing contacts 9 6 73 and 7 4 76 Thisallowsthe capacity control thermostat T3 to energize solenoid valve UL1 3 73 loading the compressor or to energize solenoid valve UL2 3 76 unloading the compressor Compressor 1 is fully loaded Compressors 2 and 3 are being capacity modulated PUMPDOWN SEQUENCE STAGE 3 PUMPDOWN in return water temperature will cause the third step of the staging thermostat T1 to open thereby de energizing staging relay R3 opening contacts 8 5 9 6 and 7 4 Liquid line solenoid SOL3 will de energize stopping the flow of refrigerant to chiller circuit 3 The compressor will continue to run until the chiller circuit has been cleared of refrigerant and the suction pressure is approximately 35 PSIG Low pressure control LP3 contact will the
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