Refrigerant Circuit
Si18-525B
96
Refrigerant Circuit
1.
Refrigerant Circuit
1.1
Outdoor Units
No. in
refrigerant
system
diagram
Symbol
Name
Major Function
A
M1C
Inverter compressor (INV)
Inverter compressor is operated on frequencies between 52 Hz and 190 Hz by using
the inverter.
25 steps
D
M1F
M2F
Inverter fan
Since the system is of air heat exchanging type, the fan is operated at 8-step rotation
speed by using the inverter.
E
Y1E
Electronic expansion valve
(Main: EV1)
While in heating operation, PI control is applied to keep the outlet superheated degree
of air heat exchanger constant.
F
Y2E
Electronic expansion valve
(Subcool: EV2)
PI control is applied to keep the outlet superheated degree of subcooling heat
exchanger constant.
G
Y1S
Solenoid valve (Hot gas: SVP) Used to prevent the low pressure from transient falling.
J
Y2S
Solenoid valve (Receiver gas
discharging: SVG)
Used to collect refrigerant to receiver.
M
Y3S
Four way valve
Used to switch the operation mode between cooling and heating.
N
S1NPH High pressure sensor
Used to detect high pressure.
O
S1NPL Low pressure sensor
Used to detect low pressure.
P
S1PH
HP pressure switch (For INV
compressor)
In order to prevent the increase of high pressure when a malfunction occurs, this
switch is activated at high pressure of 4.0 MPa or more to stop the compressor
operation.
S
—
Fusible plug
In order to prevent the increase of pressure when abnormal heating is caused by fire
or others, the fusible part of the plug is molten at a temperature of 70 to 75°C to
release the pressure into the atmosphere.
T
—
Pressure regulating valve 1
(Receiver to discharge pipe)
This valve opens at a pressure of 2.0 to 2.7 MPa for prevention of pressure increase,
thus resulting in no damage of functional parts due to the increase of pressure in
transportation or storage.
1
R1T
Thermistor (Outdoor air: Ta)
Used to detect outdoor temperature, correct discharge pipe temperature, and others.
2
R2T
Thermistor (Suction pipe: Ts)
Used to detect suction pipe temperature, keep the suction superheated degree
constant in heating operation, and others.
3
R3T
Thermistor (INV discharge
pipe: Tdi)
Used to detect discharge pipe temperature, make the temperature protection control of
compressor, and others.
4
R4T
Thermistor (Heat exchanger
deicer: Tb)
Used to detect liquid pipe temperature of air heat exchanger, determine defrosting
operation, and others.
5
R5T
Thermistor (Subcooling heat
exchanger gas pipe: Tsh)
Used to detect gas pipe temperature on the evaporation side of subcooling heat
exchanger, keep the superheated degree at the outlet of subcooling heat exchanger
constant, and others.
Summary of Contents for D-Series
Page 1: ...Si18 525B Applied Models Super Multi Plus Cooling only Super Multi Plus Heat Pump D Series ...
Page 33: ...List of Functions Si18 525B 20 List of Functions ...
Page 71: ...Specifications Si18 525B 58 Specifications ...
Page 117: ...Refrigerant Flow for Each Operation Mode Si18 525B 104 Refrigerant Circuit ...
Page 171: ...Indoor Unit SkyAir Models Si18 525B 158 Function ...
Page 207: ...Test Operation and Field Setting for RA Indoor Unit Si18 525B 194 Test Operation ...
Page 336: ...Si18 525B Service Check Function Troubleshooting 323 ...
Page 469: ...Wiring Diagrams Si18 525B 456 Appendix ...
Page 475: ...Si18 525B vi Index ...
