Refrigerant Circuit; Rxyq72M, 96M; Refrigerant Circuit Part - Daikin RXYQ72 Serivce Manual

Refrigerant Circuit

1.

Refrigerant Circuit

1.1

RXYQ72M, 96M

No. in
refrigerant
Symbol
system
diagram
A M1C Inverter compressor (INV)
B M2C Standard compressor 1 (STD1)
D M1F Inverter fan
Electronic expansion valve
E Y1E
(Main: EV1)
Electronic expansion valve
F Y2E
(Subcool: EV2)
G Y1S Solenoid valve (Hot gas: SVP)
Solenoid valve (Oil
H Y2S
equalization: SVO)
Solenoid valve (Receiver gas
I Y3S
charging: SVL)
Solenoid valve (Receiver gas
J Y4S
discharging: SV)
Solenoid valve (Non-operating
K Y5S
unit gas discharging SVSG)
Solenoid valve (Non-operating
L Y6S
unit liquid pipe closing: SVSL)
M Y7S 4-way valve
N S1NPH High pressure sensor
O S1NPL Low pressure sensor
HP pressure switch (For INV
P S1PH
compressor)
HP pressure switch (For STD
Q S2PH
compressor 2)
S — Fusible plug
Pressure regulating valve 1
T —
(Receiver to discharge pipe)
Pressure regulating valve 2
U —
(Liquid pipe to receiver)
Pressure regulating valve 3
V — (Equalizing pipe to discharge
pipe)
1 R1T Thermistor (Outdoor air: Ta)
2 R2T Thermistor (Suction pipe: Ts)
Thermistor (INV discharge
3 R31T
pipe: Tdi)
Thermistor (STD1 discharge
4 R32T
pipe: Tds1)
Thermistor (Heat exchanger
6 R4T
deicer: Tb)
Thermistor (Subcooling heat
7 R5T
exchanger gas pipe: Tsh)
Thermistor (Receiver outlet
8 R6T
liquid pipe: Tl)
Thermistor (Oil equalizing pipe:
9 R7T
To)
24
Name
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.
Since the system is of air heat exchanging type, the fan is operated at 8-step rotation
speed by using the inverter.
While in heating operation, PI control is applied to keep the outlet superheated degree of
air heat exchanger constant.
PI control is applied to keep the outlet superheated degree of subcooling heat exchanger
constant.
Used to prevent the low pressure from transient falling.
Used for oil equalizing among outdoor units in multiple-outdoor-unit system.
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.
Used to collect refrigerant to receiver.
Used to prevent the accumulation of refrigerant in non-operating outdoor units in the
case of multiple-outdoor-unit system.
Used to prevent the accumulation of refrigerant in non-operating outdoor units in the
case of multi-outdoor unit system.
Used to switch the operation mode between cooling and heating.
Used to detect high pressure.
Used to detect low pressure.
In order to prevent the increase of high pressure when a malfunction occurs, this switch
is activated at high pressure of 550 psi or more to stop the compressor operation.
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 158 to 167°F to release
the pressure into the atmosphere.
This valve opens at a pressure of 290 to 390 psi for prevention of pressure increase, thus
resulting in no damage of functional parts due to the increase of pressure in
transportation or storage.
Used to detect outdoor temperature, correct discharge pipe temperature, and others.
used to detect suction pipe temperature, keep the suction superheated degree constant
in heating operation, and others.
used to detect discharge pipe temperature, make the temperature protection control of
compressor, and others.
Used to detect liquid pipe temperature of air heat exchanger, determine defrosting
operation, and others.
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.
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.
Used to detect equalizing pipe temperature, opening/closing of the equalizing pipe stop
valve, and others.
Major Function
SiUS39-601
Refrigerant Circuit