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SiUS30-1301
Special Operation
Function and Control
61
7.1.2 Oil Return Operation in Heating or Cooling/Heating Simultaneous
Operation
Tc: High pressure equivalent saturation temperature
Te: Low pressure equivalent saturation temperature
[Starting conditions]
Start oil return operation in heating referring to the following conditions.
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. And cumulative oil return is
calculated based on Tc, Te compressor load.
Inverter compressor
74 Hz
Ending condition
2 minutes
Four way valve (Main)
ON
Heat exchanger mode
Parts Name
Preparation
Electric
Symbol
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)
During Oil Return
Operation
After Oil Return
Operation
Same as normal
heating operation
Thermostat ON/OFF:
Indoor unit control
Thermostat OFF:
OFF
Y7S = OFF: 2000 pulse
Y7S = ON : 180 pulse
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
320 pulse
OFF
320 pulse
Max. 8 minutes
0 pulse
ON
OFF
OFF
OFF
ON
Normal control
Normal control
Indoor unit control
Normal control
Max. 3 minutes
Cooling Branch Selector unit
actuator
Electric
symbol
Oil return operation
Heating Branch Selector unit
actuator
Electric
symbol
Oil return operation
Electronic expansion valve (EVH)
Y4E
600pulse
Electronic expansion valve (EVH)
Y4E
600pulse
Electronic expansion valve (EVL)
Y5E
760pulse (fully open)
Electronic expansion valve (EVL)
Y5E
760pulse (fully open)
Electronic expansion valve (EVHS)
Y2E
480pulse (fully open)
Electronic expansion valve (EVHS)
Y2E
480pulse (fully open)
Electronic expansion valve (EVLS)
Y3E
480pulse (fully open)
Electronic expansion valve (EVLS)
Y3E
480pulse (fully open)
Electronic expansion valve (EVSC)
Y1E
0pulse
Electronic expansion valve (EVSC)
Y1E
0pulse