Outline of Control (Indoor Unit)
SiUS371901E
147
Functions and Control
9.6
Control of Electronic Expansion Valve
Electronic expansion valves in indoor units have the functions of conducting superheating degree
control in cooling operation and subcooling degree control in heating operation. However, if the
indoor units receive any control command such as a protection control command or a special
control command from the outdoor unit, the units will give a priority to the control command.
• Superheating degree control in cooling operation
This function is used to adjust the opening of the electronic expansion valve so that superheating
degree (SH), which is calculated from the detection temperature (Tg) of the gas pipe thermistor
(R3T) and the detection temperature (Tl) of the liquid temperature thermistor (R2T) of the indoor
unit, will come close to a target superheating degree (SHS).
At that time, correction to the superheating degree is made according to the differences (
∆
T)
between set temperature and suction air temperature.
• Normally 5°C (9°F)
• As
∆
T (Remote controller set temp. – Suction air temp.) becomes larger, SHS becomes
lower.
• As
∆
T (Remote controller set temp. – Suction air temp.) becomes smaller, SHS becomes
higher.
• Subcooling degree control in heating operation
This function is used to adjust the opening of the electronic expansion valve so that the high
pressure equivalent saturated temperature (Tc), which is converted from the detected pressure of
the high pressure sensor in the outdoor unit, and the subcooling degree (SC), which is calculated
from the detected temperature (Tl) of the liquid temperature thermistor (R2T) in the indoor unit, will
come close to the target subcooling degree (SCS).
At that time, corrections to the subcooling degree are made according to differences (
∆
T) between
set temperature and suction air temperatures.
• Normally 5°C (9°F)
• As
∆
T (Remote controller set temp. – Suction air temp.) becomes larger, SCS becomes
lower.
• As
∆
T (Remote controller set temp. – Suction air temp.) becomes smaller, SCS becomes
higher.
SH = Tg – Tl
SH: Evaporator outlet superheating degree
Tg: Indoor unit gas pipe temperature (R3T)
Tl: Indoor unit liquid pipe temperature (R2T)
SHS (Target SH value)
SHS: Target superheating degree
SC = Tc – Tl
SC: Condenser outlet subcooling degree
Tc: High pressure equivalent saturated temperature
detected by the high pressure sensor (S1NPH)
Tl: Indoor unit liquid pipe temperature (R2T)
SCS (Target SC value)
SCS: Target subcooling degree
Summary of Contents for REYQ-XA
Page 1: ...Service Manual SiUS371901E REYQ72 456XATJU REYQ72 456XAYDU REYQ72 432XAYCU Heat Recovery 60 Hz...
Page 415: ...SiUS371901E Wiring Diagrams Appendix 402 REYQ144 168XATJU 2D119206A...
Page 416: ...Wiring Diagrams SiUS371901E 403 Appendix REYQ72 96 120XAYDU 2D119207B...
Page 417: ...SiUS371901E Wiring Diagrams Appendix 404 REYQ144 168XAYDU 2D119208B...
Page 418: ...Wiring Diagrams SiUS371901E 405 Appendix REYQ72 96 120 144 168XAYCU 2D119209A...
Page 421: ...SiUS371901E Wiring Diagrams Appendix 408 FXZQ05 07 09 12 15 18TAVJU 3D110443A...
Page 423: ...SiUS371901E Wiring Diagrams Appendix 410 FXEQ07 09 12 15 18 24PVJU 3D098557A...
Page 425: ...SiUS371901E Wiring Diagrams Appendix 412 FXSQ05 07 09 12 15 18 24 30 36 48 54TAVJU C 3D110467C...
Page 426: ...Wiring Diagrams SiUS371901E 413 Appendix FXMQ07 09 12 15 18 24 30 36 48 54PBVJU 3D093209B...
Page 428: ...Wiring Diagrams SiUS371901E 415 Appendix FXHQ12 24 36MVJU 3D048116C...
Page 429: ...SiUS371901E Wiring Diagrams Appendix 416 FXAQ07 09 12 18 24PVJU C 3D075354D...
Page 435: ...SiUS371901E Wiring Diagrams Appendix 422 VAM1200GVJU 3D073270D...
Page 437: ...SiUS371901E Wiring Diagrams Appendix 424 1 4 2 Multi Branch Selector Unit BS4Q54TVJ 3D089123B...
Page 438: ...Wiring Diagrams SiUS371901E 425 Appendix BS6 8Q54TVJ 2D089122B...
Page 439: ...SiUS371901E Wiring Diagrams Appendix 426 BS10 12Q54TVJ 2D089121B...
Page 440: ...Revision History Month Year Version Revised contents 04 2019 SiUS371901E First edition...
