Manual Heat Pump Model HHPM-V.2- SEP 2012
28
blower motor, and water pump can be checked and compared to the full load current indicated on the
component nameplates
The suction and discharge pressures should be similar to the values shown on the provided test
report example sheet included at the end of this manual.
5.4 Thermostatic Expansion Valve
The Thermostatic Expansion Valve(TXV) in the Heat Pump Water Heaters acts to control the
amount of refrigerant entering the evaporator coil. The TXV prevent liquid refrigerant from returning to the
compressor
causing damage to the compressor, responds to changing load conditions and keeps the heat
pump running at optimum efficiency.
The TXV is controlled by Suction Superheat which is defined as the temperature difference
between Suction Gas Temperature (measured directly) and Saturated Suction Temperature (found on P-T
table using measured Suction Pressure).
It is very important to insure that the HPA heat pump is operating with the proper amount of Suction
Superheat.
To Calculate Suction Superheat:
a)
Read Suction Temperature in display page. (ST)
b)
Read Evaporating Temperature in display page. (ET)
c)
Calculate Suction Superheat = ST – ET
