Daikin VRV II REYQ10MY1B, Service Manual

Page: 53 / 309

Refrigerant Circuit Si39-306
42 Refirgerant Circuit
1. Refrigerant Circuit
1.1 REYQ8, 10, 12M
No. in
refrigerant
system
diagram
Symbol Name Major Function
A M1C Inverter compressor (INV) Inverter compressor is operated on frequencies between 52 Hz and 210
Hz by using the inverter, while Standard compressor is operated with
commercial power supply only. The number of operating steps is as
follows when Inverter compressor is operated in combination with
Standard compressor.
REYQ8, 10, 12M : 29 steps
B M2C Standard compressor 1(STD1)
D M1F 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) Conducts PI control to make the outlet superheat degree constant when
the air heat exchanger is used at the evaporating side during heating
operation and cooling/heating simultaneous operation.
F Y2E Electronic expansion valve (Sub: EV2)
G Y3E Electronic expansion valve (Subcool: EV3)
PI control is applied to keep the outlet superheated degree of sub-
cooling heat exchanger constant.
H Y1S Solenoid valve (Hot gas: SVP) Used to prevent the low pressure from transient falling.
I Y2S Solenoid valve (Oil equalization: SVO) Used for oil equalizing among outdoor units in multiple-outdoor-unit system.
J Y3S
Solenoid valve (Receiver gas charging:
SVL)
Used to maintain high pressure while in cooling operation at low outdoor
temperature. And also used to prevent the accumulation of refrigerant in
non-operating outdoor units in the case of multiple-outdoor-unit system.
K Y4S
Solenoid valve (Receiver gas discharging:
SVG)
Used to collect refrigerant to receiver.
L Y5S
Solenoid valve (Discharge gas pipe closing:
SVR) Used to make the discharge gas pipe pressure high during heating
operation and cooling/heating simultaneous operation.
M Y6S
Solenoid valve (Non-operating unit liquid
pipe closing: SVSL) Used to prevent the accumulation of refrigerant in non-operating
outdoor units in the case of multiple-outdoor-unit system.
N Y7S
Solenoid valve (High pressure gas pipe
pressure reduction: SVC) Used to make the discharge gas pipe pressure low during cooling
operation.
O Y8S 4-way selector valve (Main: 20S1) Changes the main air heat exchanger into condenser or evaporator.
P Y9S 4-way selector valve (Sub: 20S2) Changes the sub air heat exchanger into condenser or evaporator.
Q S1NPH High pressure sensor Used to detect high pressure.
R S2NPL Low pressure sensor Used to detect low pressure.
S 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 3.8 MPa or more to
stop the compressor operation.
T S2PH HP pressure switch (For STD compressor 1)
V – 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.
W –
Pressure regulating valve 1 (Receiver to
discharge pipe)
This valve opens at a pressure of 2 to 2.7 MPa or more for prevention of
pressure increase, thus resulting in no damage of functional parts due to
the increase of pressure in transportation or storage.
X –
Pressure regulating valve 2 (Liquid pipe to
receiver)
Y –
Pressure regulating valve 3 (Oil equalizing
pipe to discharge pipe)
Z –
Pressure regulating valve 4 (Discharge to
discharge pipe)
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 R31T Thermistor (INV discharge pipe: Tdi)
Used to detect discharge pipe temperature, make the temperature
protection control of compressor, and others.
4 R32T Thermistor (STD1 discharge pipe: Tds1)
6 R4T Thermistor (Heat exchanger deicer: Tb)
Used to detect liquid pipe temperature of air heat exchanger, determine
defrosting operation, and others.
7 R5T
Thermistor (Sub-cooling heat exchanger gas
pipe: Tsh)
Used to detect gas pipe temperature on the evaporation side of sub-
cooling heat exchanger, keep the superheated degree at the outlet of
sub-cooling heat exchanger constant, and others.
8 R6T Thermistor (Receiver outlet liquid pipe: Tl)
Used to detect receiver outlet liquid pipe temperature, prevent the drift
between outdoor units while in heating operation in the case of multiple-
outdoor-unit system, and others.
9 R7T Thermistor (Oil equalizing pipe: To)
Used to detect oil equalizing pipe temperature, opening/closing of the oil
equalizing pipe stop valve, and others.
10 R81T
Thermistor (Main heat exchanger gas pipe:
Tg1)
Detects the gas pipe temperature of the main air heat exchanger. Used
for the control making the outlet superheat degree of main air heat
exchanger constant, etc.
11 R82T
Thermistor (Sub heat exchanger gas pipe:
Tg2)
Detects the gas pipe temperature of the sub air heat exchanger. Used
for the control making the outlet superheat degree of sub air heat
exchanger constant, etc.