How to measure superheat and subcooling

[eamonn493]

I was with US Iceman,
Liquid subcool and superheat calculated as;
a)Liquid subcool- Condenser temp minus
liquid line temperature.
b)Superheat- suction line temperature
minus evaporator temperature.

Cheers

rudi

Hi Rudi
I am new to A/C but I thought S/H is calculated by using The P/T chart, Temp reading,and pressure reading on the return pipe from the evaporator. Can you use pipe temperature reading only?
Regards Eamonn

[deekay]

One of the best places I have used to get pressure on an evaporator with no acess port has been the equaliser line. Both the external equaliser line and the bulb are located at the same point so no pressure drop is involved. I undo the 1/4" flare connection on the TXV connect it to my gauge manifold open the low side valve and connect the flexible line to the equaliser port so pressure and temperature are read at the same point. Now superheat can be calculated and adjustments made. No good if a soldered equaliser line is fitted but perfect on 90% of plant.

On measuring superheat and subcooling all I remember is superheat is the sensible heat of a gas and subcooling is the sensible heat of a liquid.