Flow temp. controller
C-27
Switch setting (FTC2)
Flow temp. controller
4
C-27
4.5.6. Defrost operation
The heat pump process requires regular defrost cycles. The FTC2 operates as follows when the system receives defrost signal and
when it completes defrosting.
4.5.6.1. When defrost signal is received
3-port valve
In DHW mode the 3-port valve remains ON.
In heating mode the valve can be OFF enabling the Heat pump unit to defrost while keeping the heat in the heating circuit or switched to
ON so system is defrosted using accumulated heat.
Selection is made using Dip SW3-1
SW 3-1 Operation
OFF Remains OFF (defrost while keeping Heating circuit).
ON
Switch to ON (switch to DHW circuit to defrost. The system defrosts using
accumulated heat for defrosting).
Other factors in the Defrost operation
Heat pump status
Water circulation
pump status
Booster heater 1
status
Booster heater 2
status
Immersion heater
status
Defrost operation
ON
Electric heaters have the same control in each mode
4.5.6.2. When System completes defrost operation
All water circuit parts return to normal settings except for the Heat pump unit.
Heat Pump unit
If the unit was running in Heating or Heating ECO previous to the defrost cycle the system restricts the maximum frequency for 10 minutes
from completion of defrost. In this time it considers the operation it was previously performing.
* The maximum frequency shall be restricted as follows depending on the temperature drop of outlet water during the defrost operation.
Temperature differential at the
beginning of defrost operation
Operation
T
HE Maximum frequency is NOT restricted.
T
HE -TH1<2degC
-TH1 2degC
Maximum frequency is restricted for 10 minutes.
4.5.7. Cooling mode (not available on some models)
Cooling mode works in a similar manner to Heating mode. The heat pump unit is controlled by the FTC2 and has a 1 minute delay in starting to
allow for the Water circulation pump to start before the Heat pump unit.
The operation of the Water circulation pump is selected using Dip SW 2-3 as before
SW 2-3 Operation
OFF Always ON (to prevent water circuit from freezing)
ON
OFF 5 minutes after Heat pump unit stops operation. Then the pump will switch ON
for 1 minute OFF for 3 minutes repeatedly until the heat pump starts again.
The 3-port valve is always OFF in Cooling mode.
The Booster heaters and the Immersion heater are always OFF in Cooling mode.
4.5.8. Anti-freeze mode
Anti-freeze mode is selected using the PAR-W21MAA or local controller.
Anti-freeze mode characteristics
Anti-freeze mode
Heat pump
status
Water circulation
pump status
Booster heater 1
status
Booster heater 2
status
Immersion
heater status
ON ON ON
Booster heaters have same control as in
Heating mode
NOT USED
OFF OFF ON OFF NOT USED
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