Daikin MicroTech III DPS Installation And Maintenance Manual

Contents

Daikin MicroTech III DPS Installation And Maintenance Manual Manual pdf 59 page image

Operator’s Guidewww DaikinApplied com59 OM 1263 • MICROTECH UNIT CONTROLLERHeat Pump ControlA heat pump unit transitions between the Cooling and Heatingoperating states as described above If compressor heating isavailable it is used first to provide the heating source duringthe Heating states If compressor heating is unavailable (asduring defrost operation for example) or inadequate to meetthe heating requirements during these states, supplementalheating will be used to add to or in lieu of the compressorheatingHeat 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” on page 51 for a detail description of thecooling compressor operating sequence.Heat Pump Heating OperationWhen the unit transitions from the Fan Only to Heatingoperating state, compressor heating operation begins Referto “Inverter Compressor Heating State Descriptions” onpage 61 for a detail description of the heating compressoroperating sequence.Heat 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 – HeatPump Units Only” on page 67 for a detailed descriptionSupplemental Heating/CompressorHeating TransitionsSpecial action is required when the unit transitions from usingcompressor (heat pump) heating to supplemental heating andvise versa Normal operation is for the compressor heating toturn ON first and ramp to full capacity before turning on anysupplemental heating Once the compressor heating is atfull capacity, the supplemental heating will then ramp up anddown as necessary to satisfy the load There will however beinstances when heating is required and compressor heating isunavailable in which case the supplemental heating must turnON first. These include the following cases:• Compressor heating operation is disabled• Heat pump defrost operation is active• Dehumidification is active• Unit is 100% OA and the OAT is below the low limit setpoint of about 0° F [adjustable ] This is adjustable suchthat heat pump operation can be locked out at ambientswhere gas heat is more economicalIn the cases where compressor heating becomes availablewhile the supplemental heating is operating it is desirableto shift as much of the load as possible to the compressorheating. This is accomplished with the following sequencewhich occurs whenever compressor heating enters the NormalHeating state or leaves defrost operation while supplementalheating is active:• Inverter compressor speed is increased 5% every 15seconds up to maximum speed• Fixed speed compressor is turned ON when the invertercompressor reaches maximum speedSupplemental heating is allowed to cycle OFF normally whilethe compressor heating is ramping up When the supplementalheating has been OFF for one stage time period, normalmodulating compressor control begins from the currentcapacityWhen compressor heating is operating while supplementalheating is inactive, the supplemental heating is held inactiveuntil then compressor capacity has been operating at itsmaximum capacity and the fixed compressor is ON for onestage time period At this point the supplemental heating isenabled to start cycling to meet the load