Refrigeration Service NESLAB HX 150 Recirculating
Contents
1. Loch Not a refrigeration problem Refer to Electrical amp Control section Refer ta Hot Gas Volve section Check water against table of requirements Low refrigeration pressure valve misadjustment or failure Go to next page Note 1 Campare load size to HX catalog spec If lood size unknown determine using heat load formula Drawing 5193a cdr Rick Mills 14 Mar 1995 Troubleshooting Chart Weak cooling continued fram previous page No sight glass full See note 3 Static pressure OK See note 2 Running pressure Compressor valve failure Refer ta appropricte pump section Air ar noncandensidles in system or avercharged Reclaim refrigerant ond recharge Unit appears to be inadequate size for land Note 1 Charge is law Leak check Fix leak Compressor valve wear Replace Recharge gt compressor g lest Note 1 Compare load size to HX catalog spec If load size unknown determine using heat load formula Note 2 Refer to lemperature pressure chart Drawing 5193b cdr Note 3 Sight ale should fill with liquid upon entering coal cycle Rick Mills and empty shortly after entering heat cycle H Mar 1995 10 Troubleshooting Chart Refrigeration pressures2. Ensure that all components are protected from heat with damp rags and or metal shields Apply a slow nitrogen gas purge Braze component s in place using BAg 28 compound silver solder Remove all rags and metal shielding Inspect all brazing joints Assemble solenoid valve s internal parts this procedure is shown in the Solenoid valve replacement procedure Install new valve cores Pressurize the system and check for leaks Be sure to pres surize both sides of any solenoid valve and the high and low side of the system Evacuate the refrigeration system Charge the refrigeration system to specifications Test the unit for proper operation Install all access covers 27 Speed check Speed Check is a term used to describe how fast a unit can cool across 20 C when it is running at maximum capacity The unit of measure is degrees per minute This will provide a number that is easy to obtain and compare 1 Find the DROP figure from the table For example the HX100 with a PD 1 pump has a drop of 1 4 C 2 Divide the drop in half Example 0 7 C 3 Add this half to 20 C to find the START point Example 20 7 C 4 Subtract this half from 20 C to find the STOP point Ex ample 19 3 C Now the entire drop is centered about 20 C 5 Connect the unit s inlet and outlet with as short a loop of hose as practical Insert a thermometer with 0 1 C resolution in the loop SPEED CHECK
3. 8 200 101 7 205 103 5 210 105 4 220 108 3 230 111 1 240 114 0 250 117 1 260 120 2 275 124 4 290 128 Drawing 83 wks Rick Mills Inches mercury below one 5 April atmosphere 1995 46 METRIC CALCULATION CALCULATION US EXAMPLE HEAT LOAD CALCULATION Measure lime Waler is required ta 8 33 Ibs gal fill a container ki of known volume 1 Kolter Cooling fluid Cooling fluid Se flaw rate weight goling fluid liters hour Kg liter specific heat Cooling fluid Cooling fluid Cooling fluid flaw rate weight specific heat gal hour lbs gal SE 47 Difference Conversion to Watts between fluid inlet and outlet Keal nr X 1 16 temp of your oF instrument BTU hr X 0 293 Heal Load Kcal hour Heat Load BTU hour 240 8 33 i 19992 3243 C0R Jick Mills 3 Apr 1995 CONDENSER REQUIREMENTS AIR COOLED UNITS The unit should be located in a laboratory or clean industrial environment where ambient temperatures are inside the range of 55 F to 95 F 13 C to 35 C The unit will retain its full rated capacity in ambient temperatures to approximately 75 F 24 C Above 75 F derate the cooling capacity 1 for every 1 F above 75 F to a maximum ambient temperature of 95 F The Celsius deration is 1 for every 0 5 C above 24 C to a maximum ambient temperature of 35 C The unit must be positioned so the air intake and discharge are not impeded Air is drawn in
4. Connector invartad 5 Remove the two fluid hoses from the water inlet and outlet stubs 6 Remove the insulation from the refrigerant inlet and outlet lines 7 Unsolder the refrigerant inlet and outlet lines CAUTION The refrigerant inlet and outlet lines are stain less steel They are easily damaged by excessive heat Never apply the torch flame directly to the stainless Warm the copper fittings up slowly and evenly until the solder liquefies 8 Remove the four screws that hold the TCA mounting flange to the mounting rails 19 9 Lift the TCA straight up out of the unit Evaporator Insulation Mounting rail inverted ee Tank Gover 10 Inspect the insulation on the inside of the case walls while the TCA is removed Replace any that is wet Install insulation on the new TCA 11 Transfer the strainer from inside the old TCA to the new TCA if required 12 Clean the refrigeration stubs on the new TCA carefully prior to installation Clean the inside of the mating copper lines prior to installation 13 Lower the TCA into place and secure the mounting flange to the mounting rails CAUTION The refrigerant inlet and outlet lines are stain less steel They are easily damaged by excessive heat Solder the fittings as follows A Ensure all fittings have been carefully cleaned B Apply a paste type flux 20 C Assemble fittings D Apply nitrogen purge gas to the suction
5. increase discharge pressure Clockwise to open valve amp decrease discharge pressure Trewin 374 cdr hick Mi Ser 1935 B The second technique is to fully open the valve by turning the adjusting screw clockwise until it stops Count how many turns are required so it may be restored later Commercial flushing chemicals Commercial flushing chemicals may be used provided the chemical is not harmful to copper Examine and follow the container directions carefully 33 HOT GAS VALVE also known as Automatic Discharge Relief valve HX100 HX150 VERTICAL TYPE BASE MOUNT TYPE The HX 100 uses a vertical flow type hot gas valve located near the water tank wall The HX 150 uses a base mount type hot gas valve mounted near the center of the base of the unit OPERATION This valve is closed during the cool cycle When the unit switches to heat cycle the solenoid valve in the liquid line closes and the resulting decrease in suction pressure opens the hot gas valve This provides a path for refrigerant gas to enter the evaporator directly without going through a liquid phase providing a heating effect 34 Hot gas valve continued SETTING Observing the suction pressure while the unit is running in the heat idle cycle will indicate the setting of the hot gas valve The valve is set correctly when the suction gauge indicates 25 PSIG for any system using R 22 refrigerant The setting
6. Charge system 25 Refrigeration Components General Replacement Procedures Note Make note of the in out orientation of all components before disassembly so that they may be correctly oriented during installation The Filter Dryer should always be changed along with any other refrigeration component or when the refrig eration system has been exposed to atmospheric moisture Disconnect the unit from line voltage Remove access panels Recover system refrigerant Remove the valve cores Remove solenoid coil s Disassemble solenoid valve s this procedure is shown in the Solenoid valve replacement procedure and remove the internal components for purging Place the nut and stem back on the valve and secure snugly Protect all components that could be damaged during braz ing with damp rags and or metal shielding Apply a slow nitrogen gas purge Unsolder all components being changed and remove Remove nitrogen purge NOTE All components should be clean and silver sol dering flux applied The Filter Dryer should be the last component installed to prevent contamination Place new components into position Check that the IN OUT sides are in proper orientation in the system as notes before removal If a new solenoid valve is being installed make sure that it is disassembled see step 6 above 26 12 13 14 15 16 17 18 19 20 21 22 23
7. again be observed from the outlet hose 44 Refrigerant specifications HX100AC HX100WC HX150AC HX150WC R22 220Z 20 oz 28 oz 24 oz Hot gas settings metric 172 kPa High pressure switch cut in 200 PSI 200 PSI High pressure switch cut out 300 PSI 300 PSI Suction pressure 25 C eeTable 186 92 PSIG See Table 2 65 PSIG Discharge pressure 25 C eeTable 1 180 PSIG See Table 2 175 PSIG Table 1 HX 100AC Refrigeration Pressures coe E Suction Discharge Speed Check PSIG PSIG C min Cae ee 72 222 75 83 245 265 1 3 1 6 76 76 84 255 275 1 3 1 6 77 85 260 280 1 2 1 6 Table 2 HX 150AC Refrigeration Pressures Ambient Ambient Suction Discharge pead Check F C PSIG PSIG min 76 89 255 285 1 9 2 4 80 266 78 90 260 290 1 9 2 4 80 91 265 295 1 8 2 3 Conditions 1 Access panels removed 2 Water in reservoir 3 Circulating temp 27 C 81 F 4 Ambient measured at condenser intake 45 R22 PRESSURE TEMPERATURE CHART TEMP F TEMP F PSIG TEMP F 48 85 51 47 90 54 45 95 56 44 100 59 43 105 62 41 110 64 39 115 67 37 120 69 34 125 72 32 130 74 30 135 76 28 140 78 26 145 81 24 150 83 22 155 85 20 160 87 19 165 89 17 170 91 15 175 92 14 180 94 12 185 96 11 190 98 9 195 100
8. and remove compressor and dryer NOTE If a compressor burnout is suspected invert old compressor and drain out a small sample of oil Test the oil for acidity following the manufacturer s recommendations on the acid test kit If the oil is acidic the refrigeration system will need flushing to remove the acidic oil Replace with new oil 12 8 10 11 12 13 14 15 16 17 18 19 20 21 22 Unpack new compressor Remove plugs from the ports Compressors are typically shipped pressurized with a dry nitrogen charge Safety glasses are especially necessary when removing plugs Orient compressor so the plug will exit the port pointing away from you and others NOTE Replacement Copeland compressors already con tain an adequate oil charge It is not necessary to add any oil to the new compressor Remove the suction service port stem from the old com pressor and insert it into the new compressor Apply nitrogen purge gas to the stem Braze in place using BAg 28 silver solder compound Position the new compressor in place Position the new dryer in place Ensure the flow direction arrow points toward the solenoid valve Wrap a damp rag around the dryer Apply nitrogen purge gas to the suction service port Braze the suction and discharge lines to the compressor using BAg 28 Braze the dryer in place using BAg 28 Insert new valve cores in the Shrader valves Pressurize sy
9. service port E Warm the copper fittings slowly and evenly Do not rush this procedure Observe the flux change to a watery clear state CAUTION Never apply the torch flame directly to the stainless F Apply BAg 28 silver solder CAUTION The stainless must never be hot enough to turn cherry red This will cause oxidation and the solder will not wet the oxidized material If this oc curs stop immediately Allow fittings to cool Polish the stainless fittings with emery cloth until all traces of dark oxidation are removed 14 Disconnect nitrogen purge gas 15 Install new valve cores in the Shrader valves 16 Pressurize system and leak check 17 Evacuate system 18 Charge system to specification 19 Test system 21 WATER REGULATING VALVE REPLACEMENT present on water cooled units only A Disconnect unit from its electrical power supply 1 Recover refrigerant charge 2 Remove valve cores from both Shrader valves 3 Apply nitrogen purge gas to the discharge service port 4 Unbraze the valve s sensor pickup from the compressor discharge line 5 Braze the new valve s sensor pickup in place using BCuP3 or BCuP5 brazing compound Silver based solder is not recom mended for this joint 6 Remove nitrogen supply 7 Install new valve cores 8 Begin evacuation of refrigeration system 9 While system is being pumped down Turn the adjusting screw on the old valve fully closed CCW Count how
10. test and repair Of leak EEN 38 MBOIEMOIG COM TOS EE 39 Solenoid valve ed EE 40 Tank Coil Assembly TCA failure and repair ccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeteee 42 Reference Water regulating valve Setting ccccccccccccssseseeeeeeecceeeeeceeeeeeeeaaaeeenes 43 Refrigeration Specifications 20 0 0 cccccceeseccccceceeeeeeessseeeeeeeeeeeeeeeeenanea 44 R22 pressure temperature chat 45 Feat load Calculations 7zeegetert dree eeaeee EE ei 46 Condenser requirements Air cooled units cccccccecesseeeeeeeeeeeeeees 47 Condenser requirements Water cooled units nusssensnna1annneeneeeee 48 15 pin accessory connector optional pinout ccccccccceceeeee eee e eee 49 P nt MUNMDOLS E 50 A CAUTION This section is intended for use by qualified refrigeration techni cians only Servicing refrigeration systems is hazardous and must be performed only by qualified persons Refrigeration systems contain various hazards including but not limited to the following 1 Refrigeration systems contain refrigerant gases at very high pressures even when not running Sudden release of refrigerant gases will result in rapid expan sion and severe frostbite hazard Refrigerant gases will cause severe injury to unprotected flesh Refrigerant gases are not flammable and are chemically inert However they are heavier than air and will displace oxygen They can cause suffocation
11. through the left side of the unit and discharged through the right and rear A minimum clearance of 2 feet 0 6 meter on these three sides is necessary for ad equate ventilation Inadequate ventilation will cause a reduction in cooling capacity and in extreme cases compressor failure Excessively dusty areas should be avoided and a periodic cleaning schedule should be instituted Refer to the list below to determine the approximate amount of air intake required for the unit to retain its full rated capacity HX100 710 cfm 20100 Ipm HX150 1050 cfm 29730 Ipm 48 HX 100 Required flow gom Required flow lpm Required pressure drop Required pressure drop Required pressure drop HX 150 Required flow gom Required flow lpm Required pressure drop Required pressure drop Required pressure drop PSI BAR kPa PSI BAR kPa CONDENSER REQUIREMENTS WATER COOLED UNITS The facility cooling water supply must meet or exceed the re quirements shown below for the unit to operate at its full rated Capacity As the temperature of the cooling water supply increases the required flow and pressure of the cooling water supply in creases Example On the HX 150 if the temperature of the cooling water supply is 65 F 18 C the flow rate must be at least 1 5 gpm 5 7 lpm with a pressure differential of at least 3 5 psi 24 kPa However if the temperature of the cooling water supply rises to 85
12. 2 r iick Mile Tank Coil Assembly TCA repair A hole occurring in the evaporator may be repaired provided the hole is accessible and the capacity exists to weld stainless steel A bead of weldment can be placed over the hole The most practical method may be to remove the TCA as outlined in the Tank Coil Assembly TCA replacement procedure and take the TCA to a local welding shop Advise the welder the coil is type 304 stainless steel If the hole is inaccessible or no welding capability exists the entire TCA should be replaced 43 Water regulating valve setting The correct setting of the valve is easily determined 1 Supply cooling water to HX 2 Direct the outlet hose into a bucket or drain 3 Turn the HX on 4 Turn the setpoint to minimum The HX should enter the cool cycle Observe full flow from the outlet hose Allow it to run until all air is displaced 5 Turn setpoint to maximum The HX should enter the heat cycle Counter clockwise to close valve amp increase discharge pressure Clackwise to apan valve amp dacraaso discharga pressure C 6 Adjust the valve stem closed CCW until the flow stops 7 Slowly open the valve stem CW until a small but constant trickle is exiting the outlet hose This is the point where the valve is just beginning to crack open This is the correct setting 8 Turn setpoint to minimum The HX should enter the cool cycle Full flow should
13. Compressor Are suction and discharge pressure equal YES valve failure NO How does suction compare to spec LOW HIGH EQUAL How does How does LOW discharge HIGH LOW discharge HIGH compare to compare to spec spec EQUAL Hot gas System valve set overcharged wrong Restriction Hot Gas Compressor ar black in valve wear system valve set wrong How doe Jr or Recaver Low HIGH charge ve noncandensibles refrigerant amp SA in system recharge spec EQUAL Check for Unit meets Drawing 524l cdr specification Rick Mills leaks TI May 1995 11 Compressor replacement 1 Remove all access panels 2 Confirm that the problem is not external to the compressor electrical before proceeding If the compressor does not start run check the following A Is proper voltage present at the compressor terminals B Are all starting devices capacitors potential relays good Disconnect the unit from line voltage C Are the motor windings known to be good or bad If in doubt Ohmmeter readings of the windings may be compared to the replacement compressor 3 Recover the system refrigerant 4 Disconnect wires starting devices etc from compressor 5 Remove valve cores from both Shrader valves 6 Remove the coil from the solenoid valve and move it out of the torch area Wrap a damp rag around the solenoid valve body 7 Unsolder
14. DRAIN NORMAL CONNECTION FLUSHING CONNECTION Drawing 4271 cn A x Wills 23 Maros 1935 31 Flushing tap water system continued 4 Open valve on cooling water supply line 5 Run HX normally for 10 15 minutes The condenser flow is now reversed This reverse flow will tend to loosen any de posits Cooling performance may be less and the water regulating valve may make some vibration noise 6 Turn HX off 7 Close valve on cooling water supply 8 Restore hoses to original configuration 9 Open valve on cooling water supply line Flushing with unit turned off In either the closed facility or tap water system it is possible to flush the condenser even if it not possible or convenient to turn the HX on This method may be used for example if the HX is having other service or maintenance performed at the same time or if electricity is not available It is necessary to manually open the regulating valve to allow flow through the condenser There are two techniques A The valve may be opened by prying up the spring follower disc using two flat blade screwdrivers one on each side The valve will be open as long as the spring is compressed This is practical for a momentary opening of the valve as it does not disturb the adjustment SPRING SPRING FOLLOWER DISC Claw ay 3254 00 Rick V Ils Agr 1995 32 Flushing with unit turned off continued Counter clockwise to close valve amp
15. F 29 C the flow rate must be at least 4 0 gpm 15 Ipm with a pressure differential of at least 10 psi 69 kPa A water regulating valve located in TAP WATER line regulates the flow rate of the cooling water supply as it enters the unit The valve regulates the flow rate based on the heat load Flow through the unit stops automatically when the unit is shut off 55 F 13 C 65 F 18 C 75 F 24 C 85 F 29 C 55 F 13 C 65 F 18 C 75 F 24 C 85 F 29 C 49 15 pin Accessory Connector Optional Units with digital controllers may be modified with a 15 pin accessory connector To enable the connector slide the LOCAL REMOTE switch on the temperature controller to the REMOTE position The pin out information is listed below CO CH CH 9 15 14 13 12 11 10 15 pin D subminiature female receptacle Pin Function Chassis ground Span Indicates the maximum setpoint value the unit can be set to operate The temperature scale is 10mV C referenced to analog ground pin 6 example 350mV 35 0 C Span Indicates the minimum setpoint value the unit can be set to operate The temperature scale is 10mV C referenced to analog ground pin 6 example 50mV 5 0 C No connection Analog ground The analog ground is physically separated from the power ground throughout the unit To prevent offsets that result from ground currents the analog and power grounds are only conn
16. NESLAB HX 150 Recirculating Chiller Thermo Manual P N U00058 Rev 09 09 97 Refrigeration No part of this publication may be Service reproduced or reprinted except for personal use without the prior permission of Thermo Electron Thermo ELECTRON CORPORATION Contents General Information After Sale Support GE 2 CAUTION EE 3 Bn ee eet EE 4 Ee nee GE 4 elle 5 Troubleshooting Troubleshooting Chart Runaway cold scicccie teteteis ict taceeld ela ege ated whctestions 6 Troubleshooting Chart Runaway hot EE 7 Troubleshooting Chart Weak cooling WEE 8 Troubleshooting Chart Refrigeration pressures ceeeeeeeeeeeeeeeeeeeeeeeeeneeeeeeeeeeeee 10 Replacement E Tue EE 11 Pan MOOR heel EE 13 EEN been eege Ee eebe tee 14 MOIEMOIO WAIVE nt ute Ante Aaah eA aaa tee aaa eg 15 Tank coll assembly TCA EE 17 Water regulating WAV Ge bares des be cee eae esha vines ven ui ee seared diate tented vie ate bet ead 21 Capillary E 23 Refrigeration components general EE 25 Procedures MPSS CHECK eege eege 27 Suction Discharge pressure and Speed check sssssssnossreeereereinnnnnnnnnnnnnnnnnnnnee ee 28 Condenser maintenance air cooled amp water coole 29 Flushing closed facility system 29 Flushing tap water SVS REIN E 30 Flushing RU UE EN Commercial flushing chemicals veo cu cies coed encteyias cretevcantwecinaiecendesectegdiatctan wecewaeeassoncke 32 Hot gas valve Automatic Discharge Relief DPI 33 SEENEN 37 Leak
17. O SZ 600 SZv600 GZP600 GZP600 u pinbry DAIE A Plouajas 97600 veglSa 9Z7600 veglLSo 9ZP7600 PE9LSO 9ZP600 PEILSO aul DD Aud 09 pjouajos SU PINDI Io plouajasg ZEL600 Ze L600 862600 862600 SABA SECH JOH K DUU KO GUO 9e600 C9600 Joie CUOP OO 99200 ASSY lOD JUEL 58S 9L200 51200 yun Bulsuapueg jo ped yup Bulsuapuag jo peg ASSY LOD YUBL oo 627200 9r200 yup Bursuapuas jo peg yun Bursuapuay jo peg cOPLOO 99Z00 ASSY 99 YUBL AAS PePrZ00 6S1 200 yun Buisuspuop jo peg yun Buisuspuop jo ped Ass 109 YUEL aas JOJOU UE apejq ueg JOJEIOGBAG OPO baPrZ00 09 022 JUN Bulsuapuod 09 0 z HUN bulsuapuoy yun Bursuapuog jo ped yun Buisuapues jo ped 0S 0zz Jossaidwiay 09 0Ez Jossaidwia5 OLLZLG AJEA SES JOH 88S ILLELLO BA EA SPB JOU 389 2LLELO OAIEN SED JOH 3aS 9bLCELO OAIEN SED JOH 489 aqn Aveyides N ea HOV 041009 duu dqJ1009 de 410090 YALVM dg3 10009 dw OS L XH OSLXH QOL XH OOL XH Jl SHEd OSL XH 9 OOL XH 51
18. TO PROVE 1 4 C MINUTE TO FULL COOL 30 S u START S d 20 7 a DROP 1 4 20 0 GE Ch E STOP 19 3 d Drawing 3126 er Rick Mills 7 Mar 1995 TIME MINUTES 28 6 Ensure the fluid used is 100 water Heat the fluid to at least 30 C then turn unit to full cool 7 Begin timing as soon as the START temp 20 7 C is passed 8 Stop timing when the STOP temp 19 3 C is passed 9 Elapsed time must be one minute or less Suction Discharge Pressure and Speed Check Air Cooled Standard and High Temperature Units All Pump Types Unit Suction psi Discharge psi Speed Check C Minute HX 100 75 83 245 265 1 3 1 6 HX 150 70 73 240 270 2 0 2 5 Water Cooled Standard and High Temperature Units All Pump Types Unit Suction psi Discharge psi HX 100 86 92 180 Speed check times not HX 150 65 175 established NOTE For low temperature units please call NESLAB 29 Condenser Air Cooled The condenser should be cleaned periodically The grille cover ing the condenser is removable The best way to remove dust is to force it out in the opposite direction from which it entered If compressed air is available direct the air against the inside of the condenser If a vacuum cleaner is used apply the vacuum to the outside of the condenser Straighten any bent fins using a fin comb Condenser Water cooled The water cooled condenser generally needs no maintenance If the coolin
19. arent due to the cover and or any thread sealant used NESLAB recommends leak check ing all Schrader valves especially any that have been ac cessed during service If the system is emptied of refrigerant NESLAB recommends replacing the valve cores with new ones as a preventive mea sure If a leak is suspected but cannot be confirmed with an elec tronic leak detector NESLAB recommends using a party bal loon to trap any escaping refrigerant This will provide a visual confirmation of a leak BALLOON TEST 1 Remove valve cover if installed 2 Stretch a balloon over the Schrader valve threads 3 A leak will inflate the balloon Leave the balloon in place overnight if convenient ago G 38 SCHRADER VALVES continued 4 Replace valve core if a leak is indicated and retest 5 Replace valve cover A If it is the gasket type replace with flare seal cap NESLAB part number 009121 B Inspect flare surfaces on the valve and cap They should be smooth and free of burrs C Apply one drop of the appropriate refrigeration oil to the flared surface of the cap to prevent galling Do Not Over Oil it will displace the sealant D Apply only one drop of sealant Perma Lok LM012 recommended NESLAB partnumber 013002 to the first thread of the valve and work it around at least half way but no more than one complete turn E Hand tighten cap until is seats Apply two wrenches one on the valve body o
20. capillary tube to length shown below Capillary Tube Dimensions Unit LD Rough sa Finish oa Inches Inches Inches vum us arse Hx100WwC 0075 39 98 38 96 HX150AC 0 088 ae ee EC EE am Note These values only for Copeland R22 systems 8 Ensure the ends of the new capillary tube are closed If open cover using masking tape Transfer insulation tube from old capillary tube to new capil lary tube Score capillary tube Le 1 cm from each end Snap off at score to produce finish length shown Place capillary tube in position Form a loop with any excess length Pull back insulation from ends of cap tube Secure with a clothespin or similar clamp Introduce nitrogen purge gas in the suction service port 24 Capillary Tube Replacement continued 14 17 18 19 20 21 Braze upper end of capillary tube first using a phoson type brazing compound BCuP3 or BCuP5 This compound has a wide plastic state which will minimize the chance of liquid brazing compound wicking into the joint and blocking the end of the capillary tube Silver type solder BAg28 is not recom mended for capillary tube connections Braze the lower end to the capillary tube to the solenoid valve in a similar manner Remove the damp rag nitrogen purge and the clips holding the insulation back Reassemble solenoid valve Insert new valve cores Pressurize and leak check Evacuate system
21. coil Remove large nut from valve body Remove internal valve components Inspect interior of valve body for cleanliness and lack of burrs or Wear Disassemble new valve and transfer components to the existing valve body Install large nut onto valve body Pressurize system and leak check As the valve is normally closed be sure that both sides of the valve are pressurized Begin evacuation of system Install coil Charge system to specification Test system 41 Enclosing Tube Nut iN Plunger O Ring Valve E Eege N SEE NOTE Valve Body 5569 ba OUT Note Apply hydraulic sealant 013002 to first two threads on valve body before tightening Do not get sealant inside valve body 42 Tank coil assembly failure A hole developing in the evaporator of the Tank Coil Assembly can cause serious problems if not detected quickly Once a hole occurs refrigerant will escape into the circulating fluid Once the refrigerant is exhausted circulating fluid will be drawn in and contaminate the refrigeration system A hole in the evaporator may be recognized by a stream of refrigerant bubbles coming to the surface of the circulating fluid in the tank If this is observed it is vital to immediately shut the system down and drain the circulating fluid until it is below the level of the leak This will prevent fluid from being drawn into the refrigeration system Qo brawny gt 237
22. e refrigerant now a gas exits the evaporator and passes through the suction filter The refrigerant then enters the compressor at low pressure and is re compressed SUCTION x SERVICE PORT gt Suction Filter COMPRESSOR um Bu EVAPORATOR DPEN CONDENSER JI CAPILLARY TUBE SOLENOID VALVE FILTER DAYER Cunseu If the setpoint is above the actual temperature the controller is in HEAT IDLE mode The triac output opens turning the solenoid coil off The solenoid valve then drops closed This closed valve stops the flow of refrigerant During the heat idle mode when the liquid line solenoid valve is closed the pressure drops in the suction line back to the compressor When the pressure drops to a predetermined value the hot gas bypass valve will open and allow hot gas to flow to the evaporator as stated The hot gas valve opens ona decrease in pressure on its discharge port The discharge port is connected to the evaporator side of the system The refrigerant gas is now routed directly to the evaporator The gas is not allowed to condense as it has bypassed the condenser completely The hot gas passing through the evaporator coil adds some heat to the fluid then returns directly through the suction filter to the compressor This unloads the compressor resulting in lower discharge pressure higher suction pressure and less power consumption Observing the suction pressure in this mode will indicate the setting o
23. e of the temperature sensor or controller will generally result in the HEAT IDLE mode This prevents a possible freezing of the cooling fluid and resulting damage from fluid expansion SUCTION ON SERVICE PORT HOT GAS c PP ee E Ge VALVE SS EVAPORATOR rem CONDENSER TW ia D CAPILLARY TUBE SOLENOID VALVE FILTER DRYER If the setpoint is below the actual temperature the controller is in COOL mode The controller triac output provides a closure to supply line voltage to the solenoid coil The solenoid valve which is normally closed is then pulled open by the coil and a standard refrigeration cooling loop exists HEAT IDLE MODE Refrigerant as a gas is pressurized in the compressor It then enters the condenser and changes to a liquid due to the cooling provided by the fan and condenser fins Heat is given up to the air at this point The liquid refrigerant exits the condenser and passes through a filter dryer which traps contaminants and absorbs any water moisture in its desiccant element The refrig erant then passes through the open solenoid valve and enters the capillary tube The restriction of the tube meters the flow The capillary tube ends at the evaporator The evaporator is a coil located inside the fluid tank As the liquid refrigerant encounters the increased volume of the evapo rator it expands tremendously changing from a liquid to a gas and absorbing heat from the fluid cooling it in the process Th
24. ected at the unit s power supply Analog ground should only be used as a reference pin Sensor temperature current limited through 2 7K OHM resistor The fluid temperature as measured by the controller s sensor located in the reservoir can be read at this pin The temperature scale is 10mV C referenced to analog ground pin 6 example 150mV 15 0 C Setpoint out The present temperature setpoint can be read at Ss pin The temperature scale is 10mV C referenced to analog ground pin 6 example 150mV 15 0 C 10 Heater output Will source 3V at 6mA Digital display input only An external voltage can be displayed on the operator panel digital display by applying the voltage to this pin The display has a low input resistance and a full scale rating of 1 99VDC Input is referenced to analog ground pin 6 The maximum voltage applied to the display should be limited to 2VDC 5V Power supply of 5VDC 15mA maximum 5V Power supply of 5VDC 15mA maximum Setpoint in The temperature setpoint can be controlled by applying a known voltage to this pin The temperature scale is 10mV C referenced to analog ground pin 6 example 230mV 23 0 C 50 coy CCU CC GC JUelabWjaY ZO LO HU LO 989 LO ZO LO LLLELO GO LO LLLELO GO LO Bupjao uoN SIa1gp SIDISED Uc GO OQS6 S0 ae GO Doc GO Aiquiassy Wou G t DUU GZe600 Gce600 SZ2e600 Jo U
25. en purge gas into the discharge service port Braze connections using BAg 28 Orient torch flame away from the filter dryer body Any bubbling of the paint on the filter dryer indicates excessive temperature is being ap proached stop and allow to cool if this occurs Remove the damp rags and the nitrogen supply Insert new schrader valve cores Assemble the solenoid valve Do Not over tighten Use two wrenches Pressurize and leak check Evacuate system Charge system Test Install any access panels removed 15 Solenoid valve replacement Disconnect the unit from line voltage 1 Recover refrigerant 2 Remove coil 3 Remove all valve cores from the Shrader valves 4 Note the direction of flow so that the new valve can be prop erly positioned during assembly Disassemble solenoid valve and remove internal components as shown below 16 Stam nut E Collar 9 d D Body nut D Stem assembly O ring a Needle valve Temporarily remove gt these components while brazing Valve seat E Se Valve body a N Protect all components that could be affected by the solder ing flame with damp rags and metal shielding Apply a nitrogen purge gas to the system Unsolder the valve and dryer and remove Place new valve and dryer in position Check that the flow direction arrows on both devices point towards the capillary tube Wrap a damp rag arou
26. f the Hot Gas ADR valve Troubleshooting Chart Runaway cold Normal Response Calibration error Valve is stuck open Not a Refrigeration Problem Replace valve Problem is in Controller or sensor See VALVE REPLACEMENT Refer to ELECTRICAL amp CONTROL section Drawing 67 cfl Rick Mills 13 March 1995 by manipulating setpoint Troubleshooting Chart Runaway hot Is Setpoint de Normal response NO YES ls it YES NO Calibration cooling Error at all UNSURE NO See TROUBLESHOOTING WEAK COOLING Any AC volts NMO on coil Valve is stuck closed YES y PP iota Replace NO Any YES refrigeration lt valve DC volts problem on coil e Problem is in See VALVE Controller or REPLACEMENT Sensor Refer to p Test ELECTRICAL amp CONTROL section Drawing 68 cfl Rick Mills by manipulating setpoint 13 March 1995 Troubleshooting Chart Weak cooling Setpoint Yes gt dctual Normal response Load may be too big See Nate 1 same load Yes Hot Gas correctly No unsure Air cooled Clean condenser condenser lean Check fan motors and supply valtage Correct ambient and or ventilation ls ambient L Condenser OK Examine refrigeration
27. g the evaporator will tend to cancel each other out The unit will have essentially no cooling capacity at all and the fluid temperature will tend to remain constant A leak can be verified as follows Turn the unit off Slowly un screw the dust cap If a leak exists a puff of refrigerant will be observed to escape from the adjustment chamber when the cap is removed Once the pressure is released the valve will be able to operate normally Start the unit and see if performance is restored The unit can now be operated temporarily with the dust cover removed but the leak still exists and needs repair Any further leak detection inside the adjustment chamber should only be done with an electronic sniffer type detector Do not use liquid detection fluid RESONATION It has been observed that certain base mounted hot gas valves have a mechanical resonance point If the valve is adjusted to that point the valve will resonate with an audible whine or moaning sound whenever the unit is in the heat cycle If this is observed it is recommended the setting be tweaked away from the resonance point With the unit running in the heat cycle turn the adjustment screw in either direction until the noise stops Up to one complete turn in either direction is ac ceptable This will not significantly change the performance of the unit 37 SCHRADER VALVES Refrigerant leaks may occur at the valve core of Schrader valves These leaks may not be app
28. g water is particularly dirty deposits may occur and cause flow restrictions In this event flushing may be required The procedure used depends on whether a closed facility water cooling system or a tap water system is used The procedures are described on the following pages Flushing using a closed facility system 1 Turn HX off 2 Close valves on cooling water supply and return lines 3 Disconnect hoses from cooling water supply and return and reverse them FACILITY FACILITY WATER WATER O SUPPLY Cause Less Ges gt eae 6 RETURN n o RETURN NORMAL CONNECTION 30 Flushing closed facility system continued 4 Open valves on cooling water supply and return lines 5 Run HX normally for 10 15 minutes Adjust setpoint so HX cycles between heat and cool The condenser flow is now reversed This reverse flow will tend to loosen any deposits Cooling performance may be less and the water regulating valve may make some vibration noise 6 Turn HX off 7 Close valves on cooling water supply and return lines 8 Restore hoses to original configuration 9 Open valves on cooling water supply and return lines Flushing using a tap water system 1 Turn HX off 2 Close valve on cooling water supply line 3 Disconnect hoses from cooling water supply and drain and reverse them P TAP WATER TAP WATER _4 SUPPLY __i SUPPLY DRAIN SS f
29. if released in a confined area Refrigerant gases used in this product are classified as Ozone Depleting Chemicals by the US Environmental Protec tion Agency While they pose no hazard sealed inside the refrigeration system intentional release into the atmosphere is outlawed under the 1990 Clean Air Act Compressor start and run capacitors store hazardous levels of electricity even when the unit is not running or plugged in Refrigeration system components operate at high tempera tures and present a severe burn hazard COOL MODE THEORY OF OPERATION The chiller operates in two modes COOL or HEAT IDLE The controller compares setpoint to actual temperature and decides which mode is required This is a thermostatic not proportional control system The compressor pump and fan motor all run continuously regardless of mode The thermal transfer of the HEAT IDLE mode is not as efficient as the COOL mode This results in units running at little or no load to spend most of their time in the HEAT IDLE mode with brief periodic COOL periods A duty cycle of 20 COOL 80 HEAT IDLE may be typical for units running under no load This duty cycle will reverse as increasing load is applied reaching 100 COOL 0 HEAT IDLE at full load This system results in tighter temperature control than continu ally cycling the compressor on and off as is typical in a house hold refrigerator The default mode is HEAT IDLE A failur
30. is adjusted as shown in the illustrations Turning the adjustment clockwise will increase the pressure setting on either type valve Contact NESLAB Technical Service for setting specifications on systems using other refrigerants 5 16 Turn clockwise to increase pressure setting Turn clackwise to increase prassura sel tting 35 Hot Gas Valve Leak Leak in Vertical Type If a leak is suspected check for leaks carefully where the ad justing screw enters the valve body If an internal leak occurs the refrigerant will escape along the threads of the adjusting screw This will require replacement of the valve Drawing hotgas2 cdr Leak In Base Mounted Type The base mount type may develop a leak across the diaphragm Refrigerant will escape into the adjustment chamber The refrigerant will be trapped in the adjustment chamber if the dust cap is in place Over time the adjustment chamber pressure will rise from ambient to whatever pressure is present in the refrigeration system The pressure across the diaphragm will equalize The diaphragm in the valve will cease to operate correctly as it expects to have ambient air pressure on one side 36 Hot gas valve continued Dust cap Adjustment chamber Allen sacket Spring Diaphragm The result will be an open hot gas valve all the time Refrigerant will flow through both heat and cool loops simultaneously The hot gas and the liquid enterin
31. many turns are required to close it 1 gt Counter clockwise to Clockwise to closa valva amp open valve amp increase decrease discharge discharge pressure pressure AMAAN QD V Drawing 5224 cn 3t Mar 1225 22 10 11 12 13 14 15 16 17 18 19 Disassemble the two unions holding the original valve in place Remove original valve Transfer fittings to new valve Mount new valve using the two unions Turn the adjusting screw on the new valve fully closed Now back it out the number of turns observed in the previous step This will approximate the correct setting Pressurize system and leak check Evacuate system Recharge refrigeration system Test Counter clockwise ta Clockwise to close valve amp open valve amp increase decrease discharge discharge pressure pressure Kawing b247 dr 31 Mar 1285 23 Capillary Tube Replacement Refer to the appropriate callout drawings to identify the capillary tube location 1 2 3 Pull back insulation from ends of cap tube Secure with a Recover refrigerant charge Remove both valve cores clothespin or similar clamp Disassemble Solenoid valve see solenoid replacement procedure for details and illustration Wrap solenoid valve body with a damp rag Apply gaseous nitrogen purge Desolder each end of the capillary tube and remove from fittings Rough cut new
32. nd the valve and dryer and protect any other components wiring with damp rags and metal shields Apply nitrogen purge gas to the system Braze in place using BAg 28 compound silver solder Remove rags and inspect brazing Install new valve cores in the Shrader valves Assemble solenoid valve assembly Use two wrenches and do not over tighten Pressurize system and leak check The solenoid valve is closed so be sure to pressurize both sides Evacuate the refrigeration system Install coil Charge system to specification Test system Install any access panels removed 17 Tank Coil Assembly TCA replacement Temp Sensor Stirrer Motor Water Inlet Connectar Water Outlet Refrigarant Outlet Refrigerant Inlet Mounting flange Drawing 5245 cdr Rick Mills 4 Apr 1995 NOTE The evaporator coil and the water tank are one unit They cannot be separated The following procedure assumes that the pump along with its plumbing has been removed A Disconnect unit from line voltage 1 Recover refrigerant if any remains 2 Drain fluid from system 3 Remove valve cores from both Shrader valves 18 4 Remove screws from Tank Cover and lift it off the tank with all wires motors sensors etc intact Invert it and place it to the side as shown If more slack is required in the wires unplug the connector shown Temp Sensor Evaporator Stirrer motor shaft
33. ne on the cap and tighten Lo turn only DO NOT OVERTIGHTEN REFRIGERATION OIL LIQUID THREAD SEALANT d VALVE COVER VALVE COVER Gasket type Acorn type Drawing 3265 cdr Tek Mills 3 Agr 1995 39 Solenoid Coil Test The solenoid coil should be energized in the cool cycle opening the solenoid valve and off in the heat cycle The coil can be tested by removing the coil from the valve and sliding the coil over a screwdriver shaft Turn unit on and adjust setpoint up and down You should feel the coil attract the screw driver in the cool cycle and release in the heat cycle SOLENOID VALVE SCREWDRIVER If the coil never turns on either the coil is open or the control voltage is missing The coil can be tested for continuity using an Ohmmeter Turn the unit off Unplug the coil from the wiring harness and measure the coil resistance It should be 750 850 Ohms Replacements are available as a coil only or a coil assembly The assembly includes the electrical connector Refer to the parts list for part numbers If a coil is obtained locally be sure it is type OMKC 1 and rated for 208VAC Do not substitute a DC coil 40 Solenoid valve rebuild NOTE Many times the solenoid valve can be rebuilt in place completely avoiding any brazing and greatly reducing the time needed for repair Rebuild procedure See next page for illustration 1 2 10 11 12 Recover refrigerant Remove
34. stem and leak check Evacuate system Charge system to specification Test system 13 as Fan Motor Replacement Disconnect unit from its electrical power supply Note the location and orientation of the electrical wiring for installation Disconnect the electrical wiring Unbolt the fan from the base of the condensing unit Pull the fan assembly motor blade and bracket out of the unit Transfer the blade conduit and or bracket to the new motor Reassemble in reverse order 14 FILTER DRYER REPLACEMENT NOTE The filter dryer contains a desiccant which will absorb moisture from the atmosphere The filter dryer should be replaced whenever the refrigeration system has been opened and allowed to go to atmospheric pressure Unsealing and installing the new filter dryer should be left until the last pos sible minute to minimize contamination of its desiccant Disconnect the unit from line voltage wech OOA o 9 N Recover the system refrigerant Remove all Shrader valve cores Remove solenoid valve internal components See Solenoid valve replacement procedure for drawing Wrap a damp rag around the solenoid valve body Apply purge gas to the system Desolder and remove old filter dryer Place new filter dryer in position with direction of flow arrow pointing towards the liquid line solenoid valve Wrap the filter dryer body in a damp rag Introduce nitrog
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