Special Control
SiUS281117
Function and Control
39
3.2.2 Oil Return Operation in Heating
Pc: High-pressure sensor detection value
Pe: Low-pressure sensor detection value
Tc: High-pressure equivalent saturation temperature
Te: Low-pressure equivalent saturation temperature
Ts: Suction pipe temperature detected by thermistor
[Conditions to start]
The heating oil return operation is started referring following conditions.
Integrated amount of displaced oil
Timer
(After the power is turned ON, integrated operating-time is 2 hours and subsequently every 8
hours.)
In addition, integrated amount of displaced oil is derived from Tc, Te, and the compressor
load.
From the preparing oil return operation to the oil return operation, and from the oil return
operation to the operation after oil return, the compressor stops for 1 minute to reduce noise
on changing of the four-way valve.
Parts Name Symbol
Electric Symbol
Oil return preparation
operation
Oil return operation
Post-oil-return
operation
RZR18/24/32P
RZQ18/24/30P
RZR36/42P
RZQ36/42P
Compressor
(INV.)
M1C
M1C
Upper limit control
124 Hz
2-step increase from
52 Hz to (Pc – Pe >
58 psi) time
Outdoor unit
fan
M1F
M1F
M2F
STEP 8
OFF
STEP 8
Four-way
valve
20S1
Y1S
Y1S
ON
OFF
ON
Electronic
expansion
valve (Main)
EV1
Y1E
Y1E
SH control
1400 pls
200~400 pls
Solenoid
valve (Hot
gas)
SVP
Y2S
Y2S
OFF
ON
ON
Solenoid
valve
(Receiver
gas
discharging)
SVG
Y3S
ON
ON
OFF
Ending conditions
130 seconds
6 minutes
Ts – Te < 9°F
160 seconds
Pc – Pe > 58 psi
OR
OR
Indoor unit actuator
Heating oil return operation
Fan
Thermostat ON unit
OFF
Stopping unit
OFF
Thermostat OFF unit
OFF
Electronic expansion valve
Thermostat ON unit
500 pls
Stopping unit
500 pls
Thermostat OFF unit
500 pls
