AquaEdge® High-Efficiency Variable-Speed Screw Chiller Unit 23XRV | General Maintenance

WARNING: HFC-134a will dissolve oil and some non-metallic materials, dry the skin, and, in heavy concentrations, may displace enough oxygen to cause asphyxiation. In handling this refrigerant, protect the hands and eyes and avoid breathing fumes.

Adding Refrigerant

• Follow the procedures described in the Charge Refrigerant into Chiller section, page 79.

CAUTION: Always use the compressor pumpdown function in the Control Test mode to turn on the evaporator pump and lock out the compressor when transferring refrigerant. Liquid refrigerant may flash into a gas and cause possible freezeup when the chiller pressure is below 35 psig (241 kPa).

Removing Refrigerant

• If the optional pumpout system is used, the 23XRV refrigerant charge may be transferred to a storage vessel or within the condenser or cooler if isolation valves are present. Follow procedures in the Pumpout and Refrigerant Transfer Procedures section when removing refrigerant from the storage tank to the chiller

Adjusting the Refrigerant Charge

• If the addition or removal of refrigerant is required for improved chiller performance, follow the procedures given under the Trim Refrigerant Charge section, on page 94.

Refrigerant Leak Testing

• Because HFC-134a is above atmospheric pressure at room temperature, leak testing can be performed with refrigerant in the chiller.

• Use an electronic leak detector, halide leak detector, soap bubble solution, or ultra-sonic leak detector. Be sure that the room is well ventilated and free from concentration of refrigerant to keep false readings to a minimum.

• Before making any necessary repairs to a leak, transfer all refrigerant from the leaking vessel. The chiller should be leak tested at least once per year.

Refrigerant Leak Rate

• ASHRAE recommends that chillers should be immediately taken off line and repaired if the refrigerant leakage rate for the entire chiller is more than 10% of the operating refrigerant charge per year

• Additionally, Carrier recommends that leaks totaling less than the above rate but more than a rate of 1 lb (0.5 kg) per year should be repaired during annual maintenance or whenever the refrigerant is pumped over for other service work.

Test After Service, Repair, or Major Leak

• If all refrigerant has been lost or if the chiller has been opened for service, the chiller or the affected vessels must be pressured and leak tested. Refer to the Leak Test Chiller section to perform a leak test.

REFRIGERANT TRACER

• Use an environmentally acceptable refrigerant as a tracer for leak test procedures.

TO PRESSURIZE WITH DRY NITROGEN: Another method of leak testing is to pressure with nitrogen only and use soap bubble solution or an ultrasonic leak detector to determine if leaks are present. This should only be done if all refrigerant has been evacuated from the vessel.

• Connect a copper tube from the pressure regulator on the cylinder to the refrigerant charging valve. Never apply full cylinder pressure to the pressurizing line. Follow the listed sequence.

• Open the charging valve fully

• Slowly open the cylinder regulating valve

• Observe the pressure gage on the chiller and close the regulating valve when the pressure reaches test level. Do not exceed 140 psig (965 kPa).

• Close the charging valve on the chiller. Remove the copper tube if no longer required.

Repair the Refrigerant Leak, Retest, and Apply Standing Vacuum Test

• After pressurizing the chiller, test for leaks with a soap bubble solution, an electronic leak detector, a halide torch, or an ultrasonic leak detector. Bring the chiller back to atmospheric pressure, repair any leaks found, and retest.

• After retesting and finding no leaks, apply a standing vacuum test. Then dehydrate the chiller. Refer to the Chiller Dehydration in the Before Initial Start-Up section, page 71.

Trim Refrigerant Charge

• If it becomes necessary to adjust the refrigerant charge to obtain optimum chiller performance, operate the chiller at design load and then add or remove refrigerant slowly until the difference between LEAVING CHILLED LIQUID chilled liquid temperature and the EVAP REFRIG LIQUID TEMP reaches design conditions. Do not .overcharge

• For superheat information, see the Troubleshooting Guide section on page 100.

• Refrigerant may be added either through the optional storage tank or directly into the chiller as described in the section entitled, Refrigerant Charging.

• To remove any excess refrigerant, follow the procedure in Transfer Refrigerant from Chiller to Storage Tank Vessel section, Steps 1a, b on page 91.