Daikin RXSQ24TAVJU Service Manual page 61

SiUS331708EA
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
Ts1 : Suction pipe temperature detected by thermistor R3T (suction pipe 1)
Tb : Heat exchanger temperature
Starting conditions
Referring to the set conditions for the following items, start oil return operation in heating.
• Integrated amount of displaced oil
• Timer setting (After the power is turned ON, integrated operating time is two hours and subsequently every
eight hours.)
In addition, integrated amount of displaced oil is derived from Tc, Te, and compressor load.
Electric symbol
Outdoor unit
actuator
24/36 class 48 class 60 class
Compressor M1C
Outdoor fan M1F
Four way valve Y1S
Main electronic
Y1E
expansion valve
Subcooling

electronic
expansion valve
Hot gas bypass
Y2S
valve
Injection valve Y3S
Ending conditions
∗ From the preparing oil-returning operation to the oil-returning operation, and from the oil-returning operation
to the operation after oil-returning, the compressor stops for 1 minute to reduce noise on changing of the four
way valve.
Indoor fan
Electronic expansion valve
Functions and Control
Oil return preparation
operation
M1C Upper limit control → 0 rps
M1C
M1F, Fan control
M1F
M2F (Normal heating)
Y1S Y1S ON
SH control → 0 pulse
Y1E Y1E
 Normal control → 0 pulse
Y3E
OFF
 
(Up to 5 minutes 50
seconds)

Y3S OFF
• More than 4 minutes
30 seconds
• A lapse of 20 seconds
OR
from four way valve
ON → OFF
Indoor unit actuator
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Thermostat ON unit
Non-operating unit
Thermostat OFF unit
Oil return operation
STEP 25 load (24/36 class)
STEP 21 load (48/60 class)
Control dependent on the
values of Pc from STEP 3
OFF
480 pulse (Fully open)
0 pulse
OFF
OFF
• 16 minutes
OR
• Tb > 11°C (51.8°F)
&
• Ts1 – Te < 5°C (9°F)
Heating oil return operation
416 pulse
256 pulse
416 pulse
Special Control
After oil return operation
Increases 2 steps every 20
seconds from minimum
frequency until Pc – Pe >
0.4 MPa (58 psi) is achieved.
OFF → STEP 8 after
Pc – Pe > 0.4 MPa (58 psi)
ON
55 pulse
0 pulse
ON → OFF
OFF
• 160 seconds
• Pc > 2.7 MPa (391 psi)
OR
• Pc – Pe > 0.4 MPa
(58 psi)
OFF
OFF
OFF
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