Execute Defrost
The 4-way valve is switched to the cooling position to defrost
the coil. This state manages the refrigerant in the system and
assures the 4-way valve is seated before defrosting the coil.
Execute Defrost continues for 10 minutes or until the Defrost
Temperature (DFT) exceeds 51.8ºF or the discharge pressure
exceeds 426.7 psi.
Terminate Defrost
After the defrost operation is complete, the 4-way valve is
switched to the heating position. Terminate Defrost manages
the system refrigerant and assures the 4-way valve is seated
before returning to normal heating compressor operation.
Defrost Inactive
When defrost operation is in the inactive state, action of the
compressor devices is a dictated by the applicable heating or
cooling compressor state.
4 Way Reversing Valve Control
(4WV) – Heat Pump Units Only
4WV is energized (On) when the unit is in the MinDAT or
Heating operating state. $WVG is de-energized (OFF) when
the unit is in the Cooling operating state.
NOTE: Once switched, the 4WV remains in the new position
until the unit’s state changes from Cooling to MinDAT
or Heating or viceversa.
Receiver Solenoid Valve Control
(SVR)
DPS heat pump units include a receiver solenoid valve that is
used to direct the refrigerant to the receiver while switching the
valve during the defrost cycle. The SVR valve is closed most
of the time but is opened at certain points in the defrost cycle
and in the Pumpdown and Standby for Restart compressor
operating states.
Bypass Solenoid Valve Control
(SVB)
DPS units include a bypass solenoid valve that opens when
necessary to bypass refrigerant from the high to the low side of
the inverter compressor to reduce the load on the compressor.
The bypass solenoid is closed most of the time. Refer to the
descriptions of the compressor operating states and protection
control functions for details regarding when the bypass valve is
opened.
heat puMp
www.DaikinApplied.com 121 OM 1141-3 • MICROTECH UNIT CONTROLLER
To Next Page
Loading...
