Daikin VRV EMERION RXYQ-AATJA, Service Manual

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Basic Control SiUS342303E
109 Part 4 Functions and Control
5.4 Electronic Expansion Valve PI Control
Main electronic expansion valve EVM control
When the outdoor unit heat exchanging is performed via the condenser (Y5S is set to OFF), this
function is used to exert PI control on the electronic expansion valve (Y1E or Y6E) so that the
condenser outlet subcooling degree (SC) will become constant.
When the outdoor unit heat exchanging is performed via the evaporator (Y5S is set to ON), this
function is used to exert PI control on the electronic expansion valve (Y1E or Y6E) so that the
evaporator outlet superheating degree (SH) will become constant.
Subcooling electronic expansion valve EVT control
In order to make the maximum use of the subcooling heat exchanger, this function is used to exert
PI control on the electronic expansion valve (Y3E) so that the evaporator-side gas pipe
superheating degree (SH) will become constant.
SC = Tc – Tf SC:
Tc:
Tf:
Condenser outlet subcooling degree
High pressure equivalent saturated temperature
Liquid pipe temperature detected by heat exchanger liquid pipe
thermistor (R2T, R9T)
 RXYQ72-168AA:
SH = Ts – Te SH:
Ts:
Te:
Evaporator outlet superheating degree
Suction pipe before accumulator (R5T)
Low pressure equivalent saturated temperature

RXYQ192-240AA:
SH = Tg – Te SH:
Tg:
Te:
Evaporator outlet superheating degree
Suction pipe temperature detected by heat exchanger gas pipe
thermistor (R11T, R12T)
Low pressure equivalent saturated temperature
SH = Tsh – Tm SH:
Tsh:
Tm:
Evaporator outlet superheating degree
Suction pipe temperature detected by the subcooling gas pipe
thermistor (R6T)
Low or middle pressure equivalent saturated temperature