View Full Version : Discharge superheat

11-07-2015, 07:09 PM
Hi guys can you confirm this is correct as I am doubting myself

discharge superheat
1 x discharge pressure & check with comparator what temperature it is
2 x measure actual discharge temp
3 x difference between 2 give s you discharge superheat

r407c chiller @ 100%
discharge pressure 16.5 bar = 40C
discharge temp 64C
discharge superheat 24C ??????

is this correct

cheers guys

11-07-2015, 08:07 PM
Yes you are correct

11-07-2015, 08:13 PM
Thanks mate

superheat & sub cooling I am ok but was doubting myself with dsh

is a 20C diff normal

high discharge superheat short of gas ?
low discharge superheat over charged ?

11-07-2015, 08:19 PM
Each type of refrigerant is different as to discharge temperature.
20 deg sounds ok to me but have you checked suction superheat at evaporator?
If it was a screw you need minimum 15 deg C to drive refrigerant out of oil for good lubrication.

11-07-2015, 08:29 PM
Superheat 6C & sub cooling 9C
chiller operating fine just was not sure about discharge superheat

thanks again

11-07-2015, 08:32 PM
To me it's fine, as superheat perfect, not much else you can do.
What type of compressor is it.

11-07-2015, 08:34 PM
Hitachi screws mate

11-07-2015, 10:51 PM
Hitachi screws mate

No no problem then

12-07-2015, 11:41 PM
Forgot to ask oil temperature of screw & how it is cooled, as that can also influence discharge temperature (although yours still sounds ok)

oil il temp should be approx 15 deg C higher than SDT & discharge temp a bit higher than oil temp.