Special Operation
SiUS30-1301
60
Function and Control
7. Special Operation
7.1
Oil Return Operation
In order to prevent the running-out of refrigerating oil in the compressor, the oil return operation is
conducted to recover oil flown out from the compressor to the system side.
7.1.1 Oil Return Operation in Cooling
Tc: High pressure equivalent saturation temperature
Te: Low pressure equivalent saturation temperature
[Starting conditions]
Start oil return operation in cooling referring to the following conditions.
Cumulative oil return amount
Timer
Cumulative compressor operating time after power supply turns ON exceeds 2 hours and the time
after the completion of previous oil return operation exceeds 8 hours.
Furthermore, the cumulative oil return is calculated according to Tc, Te, and compressor load.
Cooling Oil Return
Parts Name
Preparation
Inverter compressor
Four way valve (Main)
Normal control
Normal control
—
—
Ending condition
20 seconds
Max. 8 minutes
Max. 3 minutes
—
—
Electric
Symbol
During Oil Return
Operation
After Oil Return
Operation
Same as normal
cooling operation
Electronic expansion
valve (Main)
Electronic expansion
valve (Subcooling)
Solenoid valve (Hot
gas)
Solenoid valve (Oil
return of water heat
exchanger)
Solenoid valve
(Receiver gas
charging)
Solenoid valve
(Receiver gas
discharging)
Solenoid valve (Non-
operating unit liquid
pipe closing)
Indoor unit fan
(Cooling)
Indoor unit electronic
expansion valve
(Cooling)
Indoor unit fan
(Heating)
Indoor unit electronic
expansion valve
(Heating)
Thermostat ON/OFF:
Indoor unit control
Thermostat OFF:
OFF
Stop/thermostat OFF:
200 pls
Thermostat ON:
Indoor unit control
Four way valve (Sub)
M1C
Y5S
Y7S
Y1E
Y3E
Y1S
Y2S
Y3S
Y4S
Y6S
M1F, M2F
Y1E
M1F, M2F
Y1E
Symbol
—
20S1
20S2
EV1
EV3
SVP
SVE
SVL
SVG
SVSL
—
EV
—
EV
104 Hz
OFF
OFF
2000 pulse
0 pulse
ON
OFF
OFF
OFF
ON
52 Hz
OFF
OFF
2000 pulse
0 pulse
ON
OFF
OFF
OFF
ON