Charge Heat Pump in AC mode even in winter??

Posted by henny on November 8, 2006, 8:50 pm

I just want to double check this method. My 15 year old Lennox HP is a
little low on refrigerant charge per the pressure charts in the
manual. (about 40 psi low on suction and 50 psi low on the high side
relative to the charts)

Lennox states when adding charge, (as opposed to complete evac. and
recharge), to heat home to 74, switch HP to AC mode, turn thermostat
to 68 degrees and block the condenser vents to build up some high side
pressure. Then introduce refrigerant until parameters are correct per
their charts.

I have no reason to doubt this. I just wanted to make sure this
method is applicable in winter ambient temps. (ie 40-50 outside
ambient)

Posted by Noon-Air on November 9, 2006, 12:10 am

>I just want to double check this method. My 15 year old Lennox HP is a
> little low on refrigerant charge per the pressure charts in the
> manual. (about 40 psi low on suction and 50 psi low on the high side
> relative to the charts)
> Lennox states when adding charge, (as opposed to complete evac. and
> recharge), to heat home to 74, switch HP to AC mode, turn thermostat
> to 68 degrees and block the condenser vents to build up some high side
> pressure. Then introduce refrigerant until parameters are correct per
> their charts.
> I have no reason to doubt this. I just wanted to make sure this
> method is applicable in winter ambient temps. (ie 40-50 outside
> ambient)

What did your tech say?? What?? You say you didn't call one?? When you get
done screwing it up, let us know what your SST and superheat is.

Posted by B-Hate-Me on November 9, 2006, 8:54 am

> Lennox states when adding charge, (as opposed to complete evac. and
> recharge), to heat home to 74, switch HP to AC mode, turn thermostat
> to 68 degrees and block the condenser vents to build up some high side
> pressure. Then introduce refrigerant until parameters are correct per
> their charts.

All this method does is simulate a clogged condenser coil.

Posted by Bob_Loblaw on November 9, 2006, 9:29 am

>> Lennox states when adding charge, (as opposed to complete evac. and
>> recharge), to heat home to 74, switch HP to AC mode, turn thermostat
>> to 68 degrees and block the condenser vents to build up some high side
>> pressure. Then introduce refrigerant until parameters are correct per
>> their charts.

>
> All this method does is simulate a clogged condenser coil.

Yes! Thank you!
I've been saying this for years to techs I know, and they all argued that
"everybody does it that way", to which I replied "that doesn't mean it's
right".
I've always maintained it's a piss-poor way to try to simulate a load...

--
Respectfully, Bob

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