Daikin ALTHERMA HT ERSQ 014 V1 - Outdoor Unit Refrigerant Circuit

Refrigerant Circuit ESIE09-08A
12 Refrigerant Circuit
1. Refrigerant Circuit
1.1 Outdoor Unit
ERRQ - ERSQ
No. in
refrigerant
system
diagram
Symbol Name Major Function
A M1C Inverter compressor (INV)
Inverter compressor is operated on frequencies between 36 Hz and 195 Hz by using the
inverter. In total there are 31 steps.
B
M1F
M2F
Inverter fan
Since the system is of air heat exchanging type, the fan is operated at 8 (9)-step rotation speed
by using the inverter.
C 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.
D Y3E
Electronic expansion valve
(Subcool: EV3)
Pl control is applied to keep the outlet superheated degree of subcooling heat exchanger
constant.
E Y2S Solenoid valve (Hot gas: SVP) Used to prevent the low pressure from transient falling.
F Y3S
Solenoid valve (Unload circuit
SVUL)
Used to the unloading operation of compressor.
G Y1S Four way valve
Used to switch the operation mode between defrosting and heating. Activated during heating
(opposite concerning indoor unit).
H S1NPH High pressure sensor Used to detect high pressure.
I S1NPL Low pressure sensor Used to detect low pressure.
J 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.
K —
Pressure regulating valve 1
(Receiver to discharge pipe)
This valve opens at a pressure of 4.0 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 (INV discharge pipe:
Tdi)
used to detect discharge pipe temperature, make the temperature protection control of
compressor, and others.
3 R3T
Thermistor 
(Suction pipe1: Ts1)
used to detect suction pipe temperature, keep the suction superheated degree constant in heating
operation, 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
(Suction pipe2: Ts2)
Used to the calculation of superheat and internal temperature of compressor etc.
6 R6T
Thermistor (Subcooling heat
exchanger gas pipe: Tsh)
Used to control of subcooling electronic expansion valve.
7 R7T
Thermistor
(Liquid pipe1: Tl1)
Liquid thermistor (internal control), and others.
8 R8T
Thermistor
(Liquid pipe2: Tl2)
Liquid thermistor (internal control), and others.