Carrier XRV Pumpout And Refrigerant Transfer Procedures, Operating the Optional Pumpout Unit

Leave the oil charge in the chiller with the oil heater and controls energized to maintain the minimum oil reservoir temperature.

After Extended Shutdown — Ensure the water sys- tem drains are closed. It may be advisable to flush the water circuits to remove any soft rust which may have formed. This is a good time to brush the tubes and inspect the Schrader fit- tings on the waterside flow devices for fouling, if necessary.

Check the cooler pressure on the CVC/ICVC default screen and compare it to the original holding charge that was left in the chiller. If (after adjusting for ambient temperature changes) any loss in pressure is indicated, check for refrigerant leaks. See Check Chiller Tightness section, page 48.

Recharge the chiller by transferring refrigerant from the pumpout storage tank (if supplied). Follow the Pumpout and Refrigerant Transfer Procedures section, below. Observe freeze-up precautions.

Carefully make all regular preliminary and running system checks. Perform a Control Test before start-up. If the compres- sor oil level appears abnormally high, the oil may have absorbed refrigerant. Ensure that the oil temperature is above 140 F (60 C) or above the cooler refrigerant temperature plus 50° F (27° C).

Cold Weather Operation — When the entering con- denser water temperature drops very low, the operator should automatically cycle the cooling tower fans off to keep the tem- perature up. Piping may also be arranged to bypass the cooling tower. The PIC II controls have a low limit tower fan output that can be used to assist in this control (terminal 11 and 12 on ISM).

Manual Guide Vane Operation — It is possible to manually operate the guide vanes in order to check control operation or to control the guide vanes in an emergency. Manu- al operation is possible by overriding the target guide vane position. Access the COMPRESS screen on the CVC/ICVC and scroll down to highlight TARGET GUIDE VANE POS. To control the position, use the INCREASE or DECREASE softkey to adjust to the percentage of guide vane opening that is desired. Zero percent is fully closed; 100% is fully open. To release the guide vanes to automatic control, press the RELEASE softkey.

NOTE: Manual control overrides the configured pulldown rate during start-up and permits the guide vanes to open at a faster rate. Motor current above the electrical demand setting, capac- ity overrides, and chilled water temperature below the control point override the manual target and close the guide vanes. For descriptions of capacity overrides and set points, see the Con- trols section.

Refrigeration Log — A refrigeration log (as shown in Fig. 34), is a convenient checklist for routine inspection and maintenance and provides a continuous record of chiller per- formance. It is also an aid when scheduling routine mainte- nance and diagnosing chiller problems.

Keep a record of the chiller pressures, temperatures, and liquid levels on a sheet similar to the one in Fig. 34. Automatic recording of PIC II data is possible by using CCN devices such as the Data Collection module and a Building Supervisor. Contact a Carrier representative for more information.

PUMPOUT AND REFRIGERANT

TRANSFER PROCEDURES

Preparation — The 19XR may come equipped with an optional pumpout storage tank, pumpout system, or pumpout compressor. The refrigerant can be pumped for service work to either the chiller compressor vessel or chiller condenser vessel by using the optional pumpout system. If a pumpout storage

tank is supplied, the refrigerant can be isolated in the storage tank. The following procedures describe how to transfer refrig- erant from vessel to vessel and perform chiller evacuations.

Always run the chiller cooler and condenser water pumps and always charge or transfer refrigerant as a gas when the chiller pressure is less than 30 psig (207 kPa). Below these pressures, liquid refrigerant flashes into gas, resulting in extremely low temperatures in the cooler/condenser tubes and possibly causing tube freeze-up.

During transfer of refrigerant into and out of the optional storage tank, carefully monitor the storage tank level gage. Do not fill the tank more than 90% of capacity to allow for refrigerant expansion. Overfilling may result in damage to the tank or personal injury.

Do not mix refrigerants from chillers that use different compressor oils. Compressor damage can result.

Operating the Optional Pumpout Unit

1.Be sure that the suction and the discharge service valves on the optional pumpout compressor are open (back- seated) during operation. Rotate the valve stem fully counterclockwise to open. Front-seating the valve closes the refrigerant line and opens the gage port to compressor pressure.

2.Ensure that the compressor hold-down bolts have been loosened to allow free spring travel.

3.Open the refrigerant inlet valve on the pumpout compressor.

4.Oil should be visible in the pumpout unit compressor sight glass under all operating conditions and during shutdown. If oil is low, add oil as described under Optional Pumpout System Maintenance section, page 75. The pumpout unit control wiring schematic is detailed in Fig. 35.

TO READ REFRIGERANT PRESSURES during pumpout or leak testing:

1.The CVC/ICVC display on the chiller control panel is suitable for determining refrigerant-side pressures and low (soft) vacuum. To assure the desired range and accu- racy when measuring evacuation and dehydration, use a quality vacuum indicator or manometer. This can be placed on the Schrader connections on each vessel (Fig. 9) by removing the pressure transducer.

2.To determine pumpout storage tank pressure, a 30 in. -0-400 psi (-101-0-2769 kPa) gage is attached to the stor- age tank.

3.Refer to Fig. 29, 30, and 36 for valve locations and numbers.

Transfer, addition, or removal of refrigerant in spring- isolated chillers may place severe stress on external piping if springs have not been blocked in both up and down directions.

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