View Full Version : Mcquay water source heat pump

28-01-2003, 02:36 AM
I have very little experience trouble shooting refrigerant flow problems on heat pumps. So let me give you guys a crack at it.
After evacuating and recharging unit, start up unit(10 min run time):
suction press:65#
head press 248#
suc temp @ inlet of water heat exchanger 46F
suc temp @ outlet of water heat exchanger 75F
suc temp @ comp ahead of reversing valve 77F
discharge line temp ahead of reversing valve 175F
discharge line temp downsteam of rev valve 175F
water temp inlet 80F
water temp outlet 75F
Seems to me suction superheat is high, discharge air temp is 90F, also seems low.
Return air @ 65-70" (*store is in very negative pressure).
This is the 2nd stage compressor in a 2 stage unit.
1st stage is inoperable, blockage in refrigerant circuit.
Got 2nd stage going to provide some heat to space and
will have to return to repair first stage.
S# 7 7L0809110

28-01-2003, 08:36 PM
Without getting into your figures too deeply to start with My first thoughts are that the air temperature may not be too bad; bear in mind that if it is a 2 stage unit then performance will drop off with only one stage running.

I always try and charge and check superheat in the cooling mode although I appreciate that may be difficult at this time of year.

With smaller heat pumps I have often found the superheat at the compressor inlet somewhat higher than I would like but when in cooling things get back to normal.

Sounds like you've had, and are having, fun on this one ;)

10-02-2003, 01:53 AM
Thats where I went wrong. I tried to adjust charge and superheat during heat mode.
When I returned to the site the other day, I turned the stat to cool and dialed the charge in.
As long as the cooling superheat is in order, I dont really care
about the heat mode superheat.
Its blowing warm, I'm off to the next adventure.