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Thermo NESLAB HX 150 Service Manual

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NESLAB HX 150
Recirculating Chiller
Thermo Manual P/N U00058
Rev. 09/09/97
Refrigeration
Service
No part of this publication may be
reproduced or reprinted except for
personal use without the prior permission
of Thermo Electron.

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Summary of Contents for Thermo NESLAB HX 150

  • Page 1 NESLAB HX 150 Recirculating Chiller Thermo Manual P/N U00058 Rev. 09/09/97 Refrigeration Service No part of this publication may be reproduced or reprinted except for personal use without the prior permission of Thermo Electron.

  • Page 2: Table Of Contents

    Contents General Information After Sale Support ..................... 2 CAUTION ........................3 Theory of operation ....................4 Cool mode ......................4 Heat/idle mode ...................... 5 Troubleshooting Troubleshooting Chart: Runaway cold ..............6 Troubleshooting Chart: Runaway hot ................ 7 Troubleshooting Chart: Weak cooling ..............8 Troubleshooting Chart: Refrigeration pressures .............

  • Page 3: After Sale Support

    Water regulating valve setting ..............43 Reference Refrigeration Specifications ..............44 R22 pressure-temperature chart ............45 Heat load calculation ................46 Condenser requirements: Air-cooled units ..........47 Condenser requirements: Water-cooled units ........48 15-pin accessory connector (optional) pinout ......... 49 Part numbers ..................

  • Page 4: Caution

    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.

  • Page 5: Theory Of Operation

    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.

  • Page 6: 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.

  • Page 7: Troubleshooting Chart: Runaway Cold

    Troubleshooting Chart: Runaway cold...

  • Page 8: Troubleshooting Chart: Runaway Hot

    Troubleshooting Chart: Runaway hot...

  • Page 9: Troubleshooting Chart: Weak Cooling

    Troubleshooting Chart: Weak cooling...
  • Page 10 Troubleshooting Chart: Weak cooling continued...

  • Page 11: Troubleshooting Chart: Refrigeration Pressures

    Troubleshooting Chart: Refrigeration pressures...

  • Page 12: Compressor

    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: Is proper voltage present at the compressor terminals? Are all starting devices (capacitors, potential relays) good? Disconnect the unit from line voltage Are the motor windings known to be...
  • Page 13 8. 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.

  • Page 14: Fan Motor

    Fan Motor Replacement 1. Disconnect unit from its electrical power supply. 2. Note the location and orientation of the electrical wiring for installation. 3. Disconnect the electrical wiring. 4. Unbolt the fan from the base of the condensing unit. 5. Pull the fan assembly (motor, blade, and bracket) out of the unit.

  • Page 15: Filter/Dryer

    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.

  • Page 16: Solenoid Valve

    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.
  • Page 17 5. Protect all components that could be affected by the solder- ing flame with damp rags and metal shielding. 6. Apply a nitrogen purge gas to the system. 7. Unsolder the valve and dryer and remove. 8. Place new valve and dryer in position. Check that the flow direction arrows on both devices point towards the capillary tube.

  • Page 18: Tank Coil Assembly (Tca)

    Tank Coil Assembly (TCA) replacement 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. Disconnect unit from line voltage. 1. Recover refrigerant, if any remains. 2.
  • Page 19 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. 5.
  • Page 20 9. Lift the TCA straight up out of the unit. 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.
  • Page 21 C. Assemble fittings. D. Apply nitrogen purge gas to the suction 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.

  • Page 22: Water Regulating Valve

    WATER REGULATING VALVE: REPLACEMENT (present on water-cooled units only) 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.
  • Page 23 10. Disassemble the two unions holding the original valve in place. 11. Remove original valve. 12. Transfer fittings to new valve. 13. Mount new valve using the two unions. 14. Turn the adjusting screw on the new valve fully closed. 15.

  • Page 24: Capillary Tube

    Capillary Tube Replacement Refer to the appropriate callout drawings to identify the capillary tube location. 1. Recover refrigerant charge. 2. Remove both valve cores. 3. Pull back insulation from ends of cap tube. Secure with a clothespin or similar clamp. 4.
  • Page 25 Capillary Tube Replacement (continued) 14. 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.

  • Page 26: Refrigeration Components General

    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.
  • Page 27 12. Ensure that all components are protected from heat with damp rags and / or metal shields. 13. Apply a slow nitrogen gas purge. 14. Braze component/s in place using BAg 28 compound silver solder. 15. Remove all rags and metal shielding. 16.

  • Page 28: Speed Check

    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.

  • Page 29: Suction Discharge Pressure And Speed Check

    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.

  • Page 30: Condenser Maintenance (Air Cooled & Water Cooled)

    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.

  • Page 31: Flushing (Tap Water System)

    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.

  • Page 32: Flushing (Unit Off)

    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.

  • Page 33: Commercial Flushing Chemicals

    Flushing with unit turned off (continued) 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.

  • Page 34: Hot Gas Valve (Automatic Discharge Relief (Adr))

    HOT GAS VALVE (also known as Automatic Discharge Relief valve) HX150 HX100 BASE MOUNT TYPE VERTICAL 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.
  • Page 35 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 is adjusted as shown in the illustrations.
  • Page 36 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.
  • Page 37 Hot gas valve (continued) 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 entering 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.

  • Page 38: Schrader Valves

    SCHRADER VALVES Refrigerant leaks may occur at the valve core of Schrader valves. These leaks may not be apparent 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.

  • Page 39: Leak Test And Repair Of Leak

    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.

  • Page 40: Solenoid Coil Test

    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.

  • Page 41: Solenoid Valve Rebuild

    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. Recover refrigerant. 2. Remove coil. 3. Remove large nut from valve body. 4.

  • Page 43: Tank Coil Assembly (Tca) Failure And Repair

    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.

  • Page 44: Water Regulating Valve Setting

    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.

  • Page 45: Refrigeration Specifications

    Refrigerant specifications HX100AC HX100WC HX150AC HX150WC Refrigerant Amount 22oz 20 oz 28 oz 24 oz Amount (metric) 624 g 567 g 794 g 680 g Hot gas settings 25 PSIG Hot gas settings (metric) 172 kPa High pressure switch - cut in 200 PSI 200 PSI High pressure switch - cut out...

  • Page 46: R22 Pressure-Temperature Chart

    R22 PRESSURE - TEMPERATURE CHART PSIG TEMP, °F PSIG TEMP, °F PSIG TEMP, °F Drawing 83.wks Rick Mills * Inches mercury below one 5 April atmosphere 1995...

  • Page 48: Condenser Requirements: Air-Cooled Units

    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 ).

  • Page 49: Condenser Requirements: Water-Cooled Units

    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.

  • Page 50: 15-Pin Accessory Connector (Optional) Pinout

    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. 15 pin D-subminiature female receptacle Pin # Function...

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