Data Aire LCS Installation, Operation And Maintenance Manual

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Data Aire LCS Installation, Operation And Maintenance Manual Manual pdf 21 page image

21407C and 104 - 121 psi for R 410A. The superheat at the compressor suction line at least 6 inchesaway from the compressor should be 8 - 15°.Note: Charging to a full liquid line sight glass should never be the sole means ofdetermining the correct refrigerant charge. Other parameters such as superheat, suctionpressure, head pressure, sub-cooling and ambient temperature are also importantparameters. A system charged to a clear sight glass is often overcharged.5.2.2. Fan Speed Control System ChargingThe standard outdoor air cooled condenser for Data Aire equipment is a Fan Speed Control system.After the field refrigerant piping is properly completed, connect the refrigerant drum to the low sideand charge with vapor. Charge with approximately three lbs. per nominal ton.For example, a model DALA 0834-COD is a nominal 8 ton unit but has two nominal four ton circuits.Charge each circuit with about 12 lbs. of refrigerant to begin. It is likely that more refrigerant will berequired to complete the charging procedure. Make sure all hoses are properly purged. From avacuum feed liquid refrigerant into the high side of the system until the pressure equalizes. At thispoint there will be about 70 - 80% of the total charge in the system.Before starting a compressor, the crankcase heater should be energized for aminimum of 12 hours to reduce the possibility of liquid slugging on start-up. Failureto energize the crankcase heater could result in compressor damage.If the system is charged from a vacuum, the preheating of the compressor is not necessary. Startthe system and allow the system to stabilize to room temperature. Bubbles in the sight glass arenot unusual at this point and can be caused by flashing from liquid line pressure drop, low sub-cooling or low charge. It is likely that more refrigerant will be required to complete the chargingprocedure. Adjust the refrigerant charge until the sub-cooling is between 8 - 10° F and the superheatis between 8 - 15° F. There may be flashing and/or bubbles in the sight glass when the system isproperly charged.The unit should be allowed to stabilize for several minutes before meaningful measurements canbe taken. After the system is allowed to stabilize, verification of a few key measurements should benoted. The discharge should be between 110 - 125° F condensing temperature and the sub-coolingshould be between 8 - 10° F depending on ambient conditions. Suction temperature should be 58PSI or greater. Measure the superheat at the compressor suction line a least 6 inches away fromthe compressor. The superheat should be between 8 - 15° F for units that are water/glycol cooledand air-cooled units with air-cooled condensers. Units with remote condensing unit should have asuperheat between 20 - 25° F at the compressor. The sub-cooling will be the same 8 - 10° F.Note: Charging to a full liquid line sight glass should never be the sole means ofdetermining the correct refrigerant charge. Other parameters such as superheat,suction pressure, head pressure, sub-cooling and ambient temperature arealso important parameters. A system charged to a clear sight glass is oftenovercharged.5.2.3. Flooded System ChargingFlooded systems are units having refrigerant circuits with an optional liquid receiver and headpressure control valve. When the ambient temperature falls during cold weather, the head pressure