Cold Weather And Your Refrigeration Units

By Glenn Minch Some things to consider when selecting outdoor refrigeration units applied in extreme cold: Cold Weather Accessories & Controls Condenser Bypass Valve Condenser Fan Cycling Control Compressor Crank Case Heater Adjustable Low Pressure Control The condenser bypass valve is used to used divert refrigerant from the condenser coil & instead pipe it right into the liquid line to maintain sufficient head pressure. This low ambient control works in any weather condition including subzero windy weather. This is the best cold weather control for your commercial refrigeration unit. The condenser fan cycling control is used to cycle outdoor condenser fan motor on & off to try & maintain system head pressure. This method may not work well in extreme cold & windy conditions. This is especially true when the condenser coil has been installed facing West. Often wind travels West to East & can over cool the condenser even with the fan cycled off. This mostly happens on extremely cold & windy days. This is why we do not believe that a condenser fan cycling control is a good choice. There may be several days a year where a cooler or freezer will not operate correctly with a condenser fan cycling control. The compressor crank case heater is used to prevent liquid refrigerant from migrating into compressor. The heater is energized all the time & keeps the compressor warm. This protects the compressor from liquid migration & liquid slugging. All outdoor condensing units should have an adjustable low pressure control. Some units come with OEM nonadjustable low pressure controls that have a settings too high for cold ambient conditions. This may cause compressor to sit idle & not cool the space to be conditioned when it gets cold out. We recommend a standard pump down setting for all outdoor compressor units. The standard pump down setting is 20# low side compressor on & 0# low side compressor off.