5.5 Electronic Expansion Valve Control
EEVA control
The positions of electronic expansion valves EEVA are controlled in steps from 0 (fully closed) to 2880 (fully open).
When the outdoor unit heat exchanging is performed via the evaporator, this function is used to exert PI control on the
electronic expansion valve EEVA so that the evaporator outlet superheated degree (SH) will become constant.
SH = Tg – Te
SH: Evaporator outlet superheated degree (°C)
Tg: Suction pipe temperature (°C ) detected by the heat exchanger gas pipe thermistor T8.
Te: Low pressure equivalent saturated
When the outdoor unit heat exchanging is performed via the condenser, this function is used to exert PI control on the
electronic expansion valve EEVA so that the condenser outlet subcooled degree (SC) will become constant.
SC = Tc – TL
SC: Condenser outlet subcooled degree (°C )
TL: Liquid pipe temperature (°C ) detected by the heat exchanger gas pipe thermistor TL.
Tc: High pressure equivalent saturated
EEVC control
The positions of electronic expansion valves EEVC are controlled in steps from 0 (fully closed) to 480 (fully open).
In order to make the maximum use of the subcool heat exchanger, this function is used to exert PI control on the electronic
expansion valve EEVC so that the evaporator-side gas pipe superheated degree (SH) or discharge temperature(T7C1) will
become constant.
SH = T6B – T6A
SH: Evaporator outlet superheated degree (°C)
T6A: Suction pipe temperature (°C ) detected by the plate heat exchanger inlet thermistor T6A.
T6B: Suction pipe temperature (°C ) detected by the plate heat exchanger outlet thermistor T6B.
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