AquaEdge® Water-Cooled Centrifugal Chiller Unit 19DV | General Maintenance

Adding Refrigerant

• Follow the procedures described in the Trim Refrigerant Charge section, page 48.

Adjusting the Refrigerant Charge

• If the addition or removal of refrigerant is required to improve chiller performance, follow the procedures given under the Trim Refrigerant Charge section, page 48.

Refrigerant Leak Testing

• Since parts of the refrigerant system operate in vacuum, noncondensables will enter the cooling systems. The PIC6 HMI will issue an alert indicating excessive purge operation.

• Leaks, which cause frequent purge cycles, should be repaired without delay. Non-condensable gas in the machine causes higher than normal condenser pressure, compressor surge at start-up, and frequent purge cycles, so locate and repair any leaks as soon as possible.

• Before making any necessary repairs to a leak, transfer all refrigerant from the vessel.

Leak Rate

• It is recommended by ASHRAE that chillers be taken off line immediately and repaired if the refrigerant leak rate for the en- tire chiller is more than 10% of the operating refrigerant charge per year.

• Carrier recommends that leaks totaling less than the above rate but more than a rate of 0.1% of the total charge per year should be repaired during annual maintenance or whenever the refrigerant is transferred for other service work.

Test After Service, Repair, or Major Leak

• If all the refrigerant has been lost or if the chiller has been opened for service, the chiller or the affected vessels must be pressure tested and leak tested. Refer to the Leak Test Chiller section on page 22 to perform a leak test.

Repair Leaks, Retest, Standing Vacuum Test

• After pressurizing the chiller, test for leaks with an electronic halide leak detector, soap bubble solution, or 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 Standing Vacuum Test and Chiller Dehydration sections (pages 22 and 24) in the Before Initial Start-Up section.

Checking Guide Vanes During normal shutdown, when the chiller is off, the guide vanes are closed. Complete the following steps to adjust posi- tion if required (see Fig. 43 and 44):

• Remove the set screw in the guide vane coupling

• Loosen the holddown bolts on the guide vane actuator

• Pull the guide vane actuator away from the suction housing.

• If required, rotate the guide vane shaft fully clockwise for first stage and counterclockwise for second stage and spotdrill the guide vane actuator shaft. Spot-drilling is necessary when the guide vane actuator sprocket set screws on the guide vane actuator shaft need to be re-seated. (Remember: Spot-drill and tighten the first set screw before spot-drilling for the second set screw.)

Trim Refrigerant Charge

• If to obtain optimal chiller performance it becomes necessary to adjust the refrigerant charge, operate the chiller at design load and then add or remove refrigerant slowly until the difference between the leaving chilled water temperature and the evaporator refrigerant temperature reaches design conditions or becomes a minimum. Do not overcharge.

• Use evaporator sight glasses to visually determine optimum charge. At steady state full load operation the evaporator tubes, as viewed in the boiling pool section of the evaporator, should be covered with liquid refrigerant — if tubes are covered, maximum efficiency is achieved and there is no benefit of additional refrigerant.

• Refrigerant may be added either through the storage tank or directly into the chiller as described in the Charge Unit with Refrigerant section on page 28.

• To remove any excess refrigerant, follow the procedure in Transfer Refrigerant from Chiller to Storage Tank Vessel section on page 45.