Heat Pump ControlA heat pump unit transitions between the Cooling, MinDAT andHeating operating states as described above If compressorheating is available it is used first to provide the heating sourceduring the MinDAT and Heating states If compressor heatingis unavailable (as during defrost operation for example) orinadequate to meet the heating requirements during thesestates, supplemental heating will be used to add to or in lieu ofthe compressor heatingWhen dehumidification operation is active, the compressorswill operate in the cooling mode and the reheat will be providedby either hot gas reheat or by the supplemental heat in theunit depending on the configuration parameter setting. Whena unit is configured for heat pump operation compressorheating will always be defined as the “primary” heating and thesupplemental heating or hot gas reheat (whichever is currentlyactive) is defined as the “secondary” heat source.Heat Pump Cooling OperationWhen the unit transitions from the Fan Only to Coolingoperating state or if dehumidification operation becomesactive while in the Fan Only state, compressor coolingoperation begins Refer to Inverter Compressor Cooling StateDescriptions for a detail description of the cooling compressoroperating sequenceHeat Pump Heating OperationWhen the unit transitions from the Fan Only to MinDAT(page 109) or Heating operating state, compressor heatingoperation begins Refer to Inverter Compressor HeatingOperation State (page 118) for a detail description of theheating compressor operating sequenceHeat Pump Defrost OperationDefrost operation is required when compressor operation is inthe Normal Heating state when frost build up on the outdoorcoil interferes with the normal heat transfer from the outdoorcoil to the ambient air Refer to Defrost Operation– Heat PumpUnits Only for a detailed descriptionoperator ’s guIdewww DaikinApplied com113 OM 1141-3 • MICROTECH UNIT CONTROLLER
