Daikin Altherma HT - Basic Control; Normal Operation

ESIE09-08B Basic Control
Function 47
2. Basic Control
2.1 Normal Operation
 Heating Operation Outdoor Unit
Heating operation is not functional at an outdoor air temperature of field setting [9-02]. Default [20°C - 24°C].
 Heating Operation Indoor Unit
Actuator Operation Remarks
Compressor Compressor PI control
Used for high pressure protection control, low
pressure
protection
control, discharge pipe
temperature protection control, and compressor
operating frequency upper limit control with
inverter protection control.
Outdoor unit fan STEP 7 or 8 All steps possible, mainly STEP 7 OR 8
Four way valve ON 
Main electronic expansion valve (EV1) PI control 
Subcooling electronic expansion valve
(EV3)
PI control 
Hot gas bypass valve (SVP) OFF
This valve turns on with low pressure protection
control.
Actuator Operation Remarks
Compressor Compressor PI control
Used for high pressure protection control, low
pressure protection
control, discharge pipe
temperature protection control, and compressor
operating frequency upper limit control with
inverter protection control.
Four way valve (Y1R) OFF Only activated during defrost.
Two way valve (K2S) = solenoid valve CLOSED Only open during defrost.
Electronic expansion valve (K1E) PI control 
Electronic expansion valve (K2E) PI control 
DC inverter pump PI control 