Daikin Altherma HT - Special Control; Startup Control

Special Control ESIE09-08B
50 Function
3. Special Control
3.1 Startup Control
This control is used to equalize the pressure in the front and back of the compressor prior to the startup of the
compressor, thus reducing startup loads. Furthermore, the inverter is turned ON to charge the capacitor.
In addition, to avoid stresses to the compressor after the startup, the following control is made and the position of the
four way valve is also determined. To position the four way valve, the ma
ster and slave units simultaneously start up.

3.1.1 Startup Control in Heating Operation
* Always after POWER ON/OFF, compressor frequency is limited. This is not the case after thermo ON/OFF/ON.
Remark: A thermostat ON demand w
ill activate the outdoor fan, followed by the outdoor compressor and finally indoor
compressor.
Outdoor Thermostat ON
Pressure equalization control
prior to startup
Startup control
STEP1 STEP2
Compressor 0 Hz 57 Hz Unload
57 Hz Unload
+2 steps/20 sec.
(until Pc - Pe>0.39MPa is achieved)
Outdoor unit fan
From starting
~ 1 min. : STEP 7
1 ~ 3 min. : STEP 3
3 ~ 5 min. : OFF
STEP8 STEP8
Four way valve Holds ON ON
Main electronic expansion
valve (EV1)
0 pls 0 pls 0 pls
Subcooling electronic
expa
nsion
valve (EV3)
0 pls 0 pls 0 pls
Hot gas bypass valve
(SVP)
OFF OFF OFF
Ending conditions
 Pc - Pe<0.3MPa
 A lapse of 1 to 5 min.
A lapse of 10 sec.
 A lapse of 130 sec.
 Pc>2.70MPa
 Pc - Pe>0.39MPa
OR
OR
Indoor
STEP1 STEP2
Indoor compressor First 10 minutes -> maximum 128 Hz* To maximum frequency
4-way valve OFF OFF
Pump
HOT START
 High pressure side > 14 bar
 Maximum 5 minutes
Gradual to PI control
OR