Carrier AquaEdge 19XR Series Start-up, Operation And Maintenance Instructions Manual

Also see for AquaEdge 19XR series: Installation instructions Start-up, operation and maintenance instructions

Contents

41If freezing temperatures are likely to occur in the chiller area, drainthe chilled water, condenser water, and the pumpout condenserwater circuits to avoid freeze-up. Keep the waterbox drains open.It is recommended not to store the refrigerant in the unit if belowfreezing temperatures are anticipated. A nitrogen holding charge isrecommended in this case.Leave the oil charge in the chiller with the oil heater and controlsenergized to maintain the minimum oil reservoir temperature.After Extended ShutdownEnsure the water system drains are closed. It may be advisable toflush the water circuits to remove any soft rust that may haveformed. This is a good time to brush the tubes and inspect theSchrader fittings on the waterside flow devices for fouling, if nec-essary.Check the cooler pressure on the HMI panel and compare it to theoriginal holding charge that was left in the chiller. If (after adjust-ing for ambient temperature changes) any loss in pressure is indi-cated, check for refrigerant leaks. See Check Chiller Tightnesssection, page 24.Recharge the chiller by transferring refrigerant from the pumpoutstorage tank (if supplied). Follow the Pumpout and RefrigerantTransfer Procedures section. Observe freeze-up precautions.Carefully make all regular preliminary and running systemchecks. If the compressor oil level appears abnormally high, theoil may have absorbed refrigerant. Ensure that the oil temperatureis above 40°F (4.4°C) or above the EVAP SAT TEMP plus 50F(27C).Cold Weather OperationWhen the entering condenser water temperature drops very low,the operator should automatically cycle the cooling tower fans offto keep the temperature up. Piping may also be arranged to bypassthe cooling tower.Manual Guide Vane OperationIt is possible to manually operate the guide vanes in order to checkcontrol operation or to control the guide vanes in an emergency.Manual operation is possible by overriding the target guide vaneposition.NOTE: Manual control overrides the configured pulldown rateduring start-up and permits the guide vanes to open at a faster rate.Motor current above the electrical demand setting, capacity over-rides, and chilled water temperature below the control point over-ride the manual target and close the guide vanes. For descriptionsof capacity overrides and set points, see the 19XR with PIC 6Controls Operation and Troubleshooting guide.Refrigeration LogA refrigeration log (as shown in Fig. 43), is a convenient checklistfor routine inspection and maintenance and provides a continuousrecord of chiller performance. It is also an aid when schedulingroutine maintenance and diagnosing chiller problems.Keep a record of the chiller pressures, temperatures, and liquidlevels on a sheet similar to the one in Fig. 43. Automatic recordingof data is possible by using CCN devices such as the Data Collec-tion module and a Building Supervisor. Contact a Carrier repre-sentative for more information.PUMPOUT AND REFRIGERANTTRANSFER PROCEDURESPreparationThe 19XR chiller may come equipped with an optional pumpoutstorage tank, pumpout system, or pumpout compressor. The re-frigerant can be pumped for service work to either the chillercompressor vessel or chiller condenser vessel by using the op-tional pumpout system. If a pumpout storage tank is supplied,the refrigerant can be isolated in the storage tank. The followingprocedures describe how to transfer refrigerant from vessel tovessel and perform chiller evacuation.IMPORTANT: A field-supplied water temperature controlsystem for condenser water should be installed. The systemshould maintain the leaving condenser water temperature ata temperature that is at least 20F (11C) above the leavingchilled water temperature.CAUTIONThe power to the pumpout compressor oil heater must be onwhenever any valve connecting the pumpout compressor tothe chiller or storage tank is open. Leaving the heater off willresult in oil dilution by refrigerant and can lead to compressorfailure.If the compressor is found with the heater off and a valve open,the heater must be on for at least 4 hours to drive the refriger-ant from the oil. When heating the oil the compressor suctionmust be open to a vessel to give the refrigerant a means toleave the compressor.CAUTIONAlways run the chiller cooler and condenser water pumps andalways charge or transfer refrigerant as a gas when the chillerpressure is less than 35 psig (241 kPa). Below these pressures,liquid refrigerant flashes into gas, resulting in extremely lowtemperatures in the cooler/condenser tubes and possibly caus-ing tube freeze-up.