Heat Pump temp defferntial - InspectionNews

Anthony Alderman · #1 (**permalink**) 02-21-2008, 07:39 PM

is there a specific temp deferential for a heat pump on heat cycle with out any emg heat???

Jim Luttrall · #2 (**permalink**) 02-21-2008, 07:59 PM

Nope. Heat pumps operate under such a wide range of temperatures, there is no "normal" temperature split.
Now, having said that, I look for about 20 degrees as a starting place, but just because it achieves or exceeds that does not mean it is working correctly.

Anthony Alderman · #3 (**permalink**) 02-21-2008, 08:03 PM

Thanks Jim. The one I had today was getting about 12-14 at most. not sure whether to call it or not, for service

Jim Luttrall · #4 (**permalink**) 02-21-2008, 08:55 PM

What was the indoor return air temp?
and the outdoor temp?
Was the outdoor coil frosted?
How long had it been running?
Were both coils clean?

Anthony Alderman · #5 (**permalink**) 02-21-2008, 09:21 PM

What was the indoor return air temp? 64

and the outdoor temp? 38

Was the outdoor coil frosted? no

How long had it been running? over night

Were both coils clean? Yes

Nick Ostrowski · #6 (**permalink**) 02-21-2008, 11:25 PM

Anthony, you'll likely get many different responses on this but I look for a differential of between 18-30 degrees in heat mode. If you were only getting a temp differential of 14 degrees tops, I would call for servicing. An exterior air temperature of 38 degrees is not so low that it should place an excessive tax on the system.

Any idea how old the system was?

Anthony Alderman · #7 (**permalink**) 02-22-2008, 06:25 AM

2002 1.5 ton for small 3rd level

I did go ahead and call for service cause it did seem really low. I just realized I had never seen any concrete numbers before sooooo I went to the guys who know

Thanks

Kevin VanderWarf · #8 (**permalink**) 02-26-2008, 09:34 AM

sorta rule of thumb but certainly logical.
If the heat pump is to perform without the strips kicking in you could expect it to produce at least 12 to 18 degrees defferntial. I think anything less than 12 and the strips would not be far from kicking in.

I have always removed the cover of the t-stat so that I can see that the first bulb only is engaged while checking the heatpump temp, then raise to engage the second bulb and look for a significant increase.
The combined stages will produce the more unpredictable temp but 100 to 130 degrees should be expected.