Daikin 2MXS-N Series Service Manual page 88

Control Specification
3.13.10 SC (Subcooling) Control
Outline The liquid pipe temperature and the heat exchanger temperature are detected and the electronic
expansion valve opening is compensated so that the SC of each room becomes the target SC.
Detail Start Conditions
After finishing the starting control (660 ~ 690 seconds, depending on the model), (all) the electronic
expansion valve(s) for the operating room is/are controlled.
Determine Electronic Expansion Valve Opening
The electronic expansion valve opening is adjusted so that the temperature difference between the
maximum heat exchanger temperature of connected room and the liquid pipe temperature
thermistor becomes constant.
3.13.11 Target Discharge Pipe Temperature Control
The target discharge pipe temperature is obtained from the indoor and outdoor heat exchanger
temperature, and the electronic expansion valve opening is adjusted so that the actual discharge
pipe temperature becomes close to the target discharge pipe temperature. (Indirect SH
(superheating) control using the discharge pipe temperature)
The electronic expansion valve opening and the target discharge pipe temperature are adjusted
every 20 seconds. The target discharge pipe temperature is controlled by indoor heat exchanger
temperature and outdoor heat exchanger temperature. The opening degree of the electronic
expansion valve is controlled by the followings.
76
When the actual SC is > target SC, open the electronic expansion valve of the room.
When the actual SC is < target SC, close the electronic expansion valve of the room.
SC
(Subcool)
Target discharge pipe temperature
Actual discharge pipe temperature
Previous discharge pipe temperature
The target discharge pipe
temperature is set as to become
the aim SH.
The inclination does not change
depending on the operating condition.
SH
(Superheat)
SiUS121502E
(R18921)
Function and Control