Carrier 17EX Start-up, Operation And Maintenance Instructions Manual

Also see for 17EX Series: Start up & operation manual Start-up, operation and maintenance instructions

Contents

NOTE: If the chiller fails to stop, in addition to action thatthe PIC initiates, the operator should close the guide vanesby overriding the guide vane target to zero (to reduce chillerload) and then by opening the main disconnect. Do not at-tempt to stop the chiller by opening an isolating knife switch.High intensity arcing may occur. Do not restart the chilleruntil the problem is diagnosed and corrected.After Limited Shutdown — No special preparationsshould be necessary. Follow the regular preliminary checksand starting procedures. Control power must be maintainedin order to keep the oil temperature hot and all control safe-ties operational. The oil pump operates occasionally to keepthe contact seal filled with oil to prevent refrigerant loss.Extended Shutdown — The refrigerant should be trans-ferred into the economizer/storage vessel (see Pumpout andRefrigerant Transfer Procedures, this page) in order to re-duce chiller pressure and the possibility of leaks. Maintaina holding charge of 5 to 10 lbs (2.27 to 4.5 kg) of refrigerantwithin the cooler/condenser/compressor sections, to preventair from leaking into the chiller.If freezing temperatures are likely to occur in the chillerarea, drain the chilled water, condenser water, and the pump-out condenser water circuits to avoid freeze-up. Keep thewaterbox drains open.Leave the oil charge in the chiller with the oil heater andcontrols energized to maintain the minimum oil reservoirtemperature.After Extended Shutdown — Be sure that the watersystem drains are closed. It may be advisable to flush thewater circuits to remove any soft rust which may have formed.This is a good time to brush the tubes if necessary.Check the cooler pressure on the LID default screen, andcompare it to the original holding charge that was left in thechiller. If (after adjusting for ambient temperature changes)any loss in pressure is indicated, check for refrigerant leaks.See the Check Chiller Tightness section, page 46.Recharge the chiller by transferring refrigerant fromthe economizer/storage vessel. Follow the Pumpout and Re-frigerant Transfer Procedures section, this page. Observefreeze-up precautions.Carefully make all regular preliminary and running sys-tem checks. Perform a controls test before start-up. If thecompressor oil level appears abnormally high, the oil mayhave absorbed refrigerant. Make sure that the oil tempera-ture is above 150 F (66 C) or above the cooler refrigeranttemperature plus 70° F (39° C).Cold Weather Operation — When the entering con-denser water temperature is very low, the PIC can automati-cally cycle the cooling tower fans off to keep the tempera-ture up. Provide a way to control the condenser watertemperature to the chiller either by arranging a tower bypasspiping system and/or adding a tower water temperature con-trol system.Manual Guide Vane Operation — It is possible tooperate the guide vane manually in order to check controloperations or control the guide vanes in an emergency. Thisis done by overriding the target guide vane position. Accessthe STATUS01 screen on the LID and highlight TARGETGUIDE VANE POS. To control the position, enter the de-sired percentage of guide vane opening. Zero percent is fullyclosed; 100% is fully open. To release the guide vanes toautomatic operation, press the RELEASE softkey.NOTE: Manual guide vane control allows the operator tomanipulate the guide vane position and override the pull-down rate during start-up. However, motor current above theelectrical demand setting, capacity overrides, and chilled wa-ter temperature below the control point will override manualguide vane control and close the guide vanes, if necessary.For descriptions of capacity overrides and set points, see theControls section.Refrigeration Log — A refrigeration log, such as theone shown in Fig. 31, is a convenient way to track routineinspection and maintenance and provides a continuous recordof chiller performance. It is an aid in scheduling routine main-tenance and in diagnosing chiller problems.Keep a record of the chiller pressures, temperatures, andliquid levels on a log similar to Fig. 31. It is possible to au-tomatically record PIC data by using CCN devices such asthe Data Collection module and a Building Supervisor ter-minal. Contact your Carrier representative for moreinformation.PUMPOUT AND REFRIGERANT TRANSFERPROCEDURESPreparation — The 17EX may come equipped withan optional pumpout compressor. The refrigerant can be pumpedfor service work to either the cooler/condenser/compressorsections or the economizer/storage vessel by using the pump-out system. The following procedures describe how to trans-fer refrigerant from vessel to vessel and perform chillerevacuations.To prevent tube freeze-up, always be sure that the con-denser and cooler water pumps are operating whenevercharging, transferring, or removing refrigerant from thechiller.If the chiller water pumps are controlled by the PIC, ac-cess the CONTROL TEST table on the LID and use thePUMPDOWN/LOCKOUT screen or TERMINATE LOCK-OUT screen to perform the functions described below. If thechiller water pumps are not controlled by the PIC, they mustbe turned on and off manually.When performing pumpout, do not leave the compres-sor unattended for long periods of time or loss of com-pressor oil may result. Periodically check oil level.Operating the Optional Pumpout Compressor1. Be sure that the suction and the discharge service valveson the optional pumpout compressor are open (back seated)during operation. Figure 32 shows the location of thesevalves (valves 2, 3, 4, 5, and 8). Rotate the valve stemfully counterclockwise to open. Front seating the valvecloses the refrigerant line and opens the gage port to com-pressor pressure.2. Make sure that the compressor holddown bolts have beenloosened to allow free spring travel.3. Open the refrigerant inlet valve on the pumpout compressor.4. Oil should be visible in the compressor sight glass underall operating conditions and during shutdown. If oil islow, add oil as described under Pumpout System Main-tenance section, page 83. The pumpout unit control wir-ing schematic is detailed in Fig. 33. The Optional Pump-out System is detailed in Fig. 34.READING REFRIGERANT PRESSURES during pumpoutor leak testing:1. The LID display on the chiller control center is suitablefor determining refrigerant-side pressures and low (soft)vacuum. To measure evacuation or dehydration pres-sures, use a quality vacuum indicator or manometer toensure the desired range and accuracy. This can be placedon the Schrader connections on each vessel by removingthe pressure transducer.63