Daikin REYQ34PY1 [154/438] Electronic expansion valve control

Daikin REYQ34PY1 [154/438] Electronic expansion valve control
Si37-701 Outline of Control (Indoor Unit)
Function 143
6.7 Electronic Expansion Valve Control
• EVM control of main motorized valve
When an evaporator is used for outdoor unit heat exchanging (20SA = ON), this function is used
to exercise the PI control on the motorized valve (Y1E) so as to keep the evaporator outlet
superheated degree (SH) constant.
• EVT control of supercooled motorized valve
In order to make full use of the supercooled heat exchanger, this function is used to exercise the
PI control on the motorized valve (Y3E) so as to keep the evaporator-side gas pipe superheated
degree (SH) constant.
• EVJ control of refrigerant charge motorized valve
To automatically charge or refill refrigerant, this function is used to exercise the PI control on the
opening degree of the motorized valve (Y2E) in response to outdoor temperatures and close the
motorized valve after the completion of charging or refilling.
Set the opening degree to 80 pls for normal operation.
SH = Tg - Te SH: Evaporator outlet superheated degree (°C)
Tg: Suction pipe temperature detected by the heat exchanger gas pipe
thermistor R2T (°C)
Te: Low pressure equivalent saturated temperature (°C)
SH = Tsh - Te SH: Evaporator outlet superheated degree (°C)
Tsh: Suction pipe temperature detected by the supercooled heat
exchanger outlet thermistor R5T (°C)
Te: Low pressure equivalent saturated temperature (°C)

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