Special Control
SiUS181305E
47
Function
3.2.2 Oil Return Operation in Heating Operation
<Conditions to start>
Oil return operation in heating operation is started referring to the following conditions:
Integrated amount of displaced oil
Timer setting (Make this setting so as to start the oil return operation when the initial cumulative
operating time reaches 2 hours after power supply is turned ON and then every 8 hours.)
The integrated amount of displaced oil is derived from Tc, Te, and the compressor load.
From the preparation to the oil return operation, and from the oil return operation to the post-oil-
return operation, the compressor stops for 1 minute to reduce noise on changing of the four way
valve.
Outdoor unit actuator
Oil return preparation
operation
Oil return operation
Post-oil-return operation
Compressor
Upper limit control
140 Hz Full load
36 Hz Unload
+2 steps / 20 sec.
(until Pc - Pe > 0.4 MPa)
(134 ftAq)
Outdoor fan
STEP 8
OFF
STEP 8
Four way valve (Y1S)
ON
OFF
ON
Main electronic expansion valve (Y1E) SH control
480 pulse
55 pulse
Subcooling electronic expansion valve
(Y3E)
0 pulse
0 pulse
0 pulse
Hot gas bypass solenoid valve (Y2S)
OFF
OFF
OFF
Ending conditions
2 min.
12 min.
Ts1 – Te < 5°C
(9°F)
Tb > 11°C
(51.8°F)
160 sec.
Pc – Pe > 0.4 MPa
(134 ftAq)
or
&
or
Indoor unit actuator
Heating oil return operation
Indoor fan
Thermostat ON unit
OFF
Stopping unit
OFF
Thermostat OFF unit
OFF
Electronic expansion valve of
BP unit
Thermostat ON unit
SH control
Stopping unit
80 pulse
Thermostat OFF unit
SH control
