WH-SXC09H3E5, WH-SXC12H6E5, WH-UX09HE5, WH-UX12HE5 - Panasonic Air Conditioner Service Manual (repair manual). Page 117

117 

Purpose of Force Heater Mode 

-  As a backup heat source when heat pump error. Force heater Mode control backup heater to heat up the 

room circuit, and turn ON back up heater or booster heater to boil up tank water base on the tank heater 
selection (internal or external) 

Force Heater Control start condition: 

-  Force heater request ON by user OR auto turn ON by remote controller during error AND 

(Force Heater mode can be operate regardless of mode selection, remocon will send the lastest mode 
selection and force bit to indoor. Indoor will judge to turn ON heater to room side if it is heat mode selected, 
and turn ON heater to heat up tank water base on tank heater selection) 

-  During Error Happen (exclude the error list below) 

Error List not allow Force Heater Operation 
 

H12 

  Capacity Mismatch 

H76 

  Indoor-Remote Controller Communication Error 

H20 

  Abnormal Water Pump 

H95 

  Abnormal Voltage Connection 

H62 

  Abnormal Water Flow 

F37 

  Abnormal Water Inlet sensor 

H70 

  Abnormal Back-up Heater OLP 

F45 

  Abnormal Water Outlet sensor 

H74 

  PCB Communication Error 

 

  [ When tank mode operate with external heater selected & tank heater select ON] 

H72 

  Abnormal tank sensor 

H91 

  Abnormal tank heater OLP 

 
Force Heater Control Stop Condition: 

-  Force Heater request OFF OR 
-  Operation OFF request OR 
- Power 

reset 

OR 

-  Error of above list happens during force heater operation. 

 
Control contents: 

1)  After fulfil start condition, indoor will operate the force heater operation according to below mode condition 
 

Heat mode Only 

:  Turn ON backup heater to achieve room heat pump target water temperature. 

 

Heat + Tank mode 

:  Turn ON backup heater to heat up room OR Turn ON Heater to Boil up tank water. 

 

Cool mode Only  

:  Water pump and backup heater will OFF in force heater mode 

 

Cool + Tank mode 

:  Operate pump and internal Heater OR External heater to Boil up tank water. 

 

Tank mode Only 

:  Operate pump and internal Heater OR External heater to Boil up tank water. 

 

* For heat mode condition, backup heater will only turn ON if the backup heater is enable regardless of Room 

 

  Heater Selection 

 

* For tank mode condition, If internal heater selected backup heater will turn ON to boil up tank water. 

 

If external heater selected, booster heater will turn ON to boil up tank water regardless of tank heater 

 selection 

 
Room Side: (Heat Mode) 

1)  When force heater mode start condition fulfilled, turn ON water pump and turn ON backup heater follow 

below control. 

2)  Operate the 3 ways valve at room side only and turn ON 2 ways valve as heat mode operation. 
3)  Turn ON the zone pump and mixing valve if system select 2 zone system or Buffer tank connect YES, control 

according to normal zone pump and mixing valve control. 

4)  When Force heater mode stop condition fulfilled, turn OFF heater as below condition and turn OFF water 

pump after pump delay time. 

 
Backup Heater On Condition: 

a)  When Force Heater Control start condition fulfill AND 
b)  After water pump operate 2 minute AND 
c)  When water outlet temperature < water set temperature + [-4°C] AND 
d)  20 minutes since previous Backup heater Off AND 
e)  Backup Heater Enable 

 
Backup Heater Stop condition 

a)  Force mode off OR 
b) Operation 

off 

OR 

c)  When water outlet temperature > water set temperature + [-2°C] for continuous 15 secs OR 

* ON/OFF follow normal heater sequence.