Specifications

SiBE04-624 Control Specification
Function and Control 79
3.14.6 Control for Abnormally High Discharge Temperature
Outline An abnormally high discharge temperature is an indication for a too high suction temperature or
super-heat. Making adjustments to the expansion valve opening can solve this problem.
Detail Increasing the expansion valve opening will increase the refrigerant flow through the evaporator
and decrease the superheat and the discharge temperature.
The unit is operating in the 'dropping zone' when all the following conditions are met:

The compressor is operating

the discharge temperature exceeds A°C
The unit is operating in the 'reset zone' when one of the following conditions are met:

The compressor has stopped

the discharge temperature is below B°C
A = 104 - correction value (a)
B = 100 - correction value (a)
For the correction value (a), refer to the Page72 "High Discharge Pipe Temperature Control".
Fig.: Abnormal high discharge temperature control graph
In the dropping zone the unit will react as follows:

Prohibit the discharge pipe temperature control

When entering the dropping zone from the reset zone, it will add 20 pulses the expansion
valve opening and set a 30 seconds 'opening adjustment timer'.

Each time the opening adjustment timer reaches zero without leaving the dropping zone, 20
pulses will be added to the expansion valve opening and the opening adjustment timer will
be reset.
A˚C
B˚C
Reset zone
Dropping zone
(R5920)