Mitsubishi Electric PAC-IF021B-E Manual page 27

4
Switch setting (FTC2)
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).
Switch to ON (switch to DHW circuit to defrost. The system defrosts using
ON
accumulated heat for defrosting).
Other factors in the Defrost operation
Water circulation
Heat pump status
pump status
Defrost operation ON
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
- TH1 2 deg C
T
HE
T - TH1 < 2 deg C
HE
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)
OFF 5 minutes after Heat pump unit stops operation. Then the pump will switch ON
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
Heat pump
Anti-freeze mode
status
ON ON
OFF OFF
Booster heater 1 Booster heater 2
status status
Electric heaters have the same control in each mode
Operation
Maximum frequency is NOT restricted.
Maximum frequency is restricted for 10 minutes.
Water circulation Booster heater 1
pump status status
Booster heaters have same control as in
ON
Heating mode
ON OFF
Immersion heater
status
Booster heater 2 Immersion
status heater status
NOT USED
NOT USED
Flow temp. controller
C-27 C-27