HVAC MeFites, please hope me

November 12, 2018 7:27 AM

Can I adjust how often my heat pump goes into defrost mode?

I previously asked this heatpump question. This is sort-of a sequel, but with all new players.

I have a Goodman GSZ140361 heatpump. It's been working great even as Indiana starts to slide into winter, making good heat well into the low 30s without ever having to lean on the aux heat. So far, so good. This morning, though, temps hit 30, and now it seems like the heatpump is going into defrost mode every other heating cycle, which seems pretty excessive to me (This is, as far as I can tell, the first time this season it's gone into defrost.) It's making great heat even when defrost kicks in, so it would seem to my uneducated mind that it shouldn't go into defrost so quickly.

I've been told by others that there should be a control on the heatpump defrost board that allows you to set how often the defrost cycle happens. I've looked at the board, but I'm not really sure what I'm looking at.

So, I'm hoping some kind HVAC MeFites might be able to guide me.

Thanks!

(I also have a new question about my new thermostat, but I'll gladly discuss that offline, so as not to pile-on the asks.)

posted by Thorzdad to Home & Garden (4 answers total)

I am not an expert in HVAC by any means, just a home owner with a heat pump. My understanding is that the unit will automatically go into defrost mode when the outside coils start to frost up. This will be dictated by how humid it is outside. When defrosting the unit is going into A/C mode moving heat from inside to outside to heat the outside coils. During this time the aux heating elements come on side the air blowing out the vents is not cold. At least this is how it was explained to me by my HVAC tech.
posted by tman99 at 8:03 AM on November 12, 2018

Response by poster: When defrosting the unit is going into A/C mode moving heat from inside to outside to heat the outside coils. During this time the aux heating elements come on side the air blowing out the vents is not cold. At least this is how it was explained to me by my HVAC tech.

I’ve gotten different responses from HVAC people I’ve asked about this. Most said that the aux coils don’t come on during defrost. I know mine don’t.

In any case, it’s not necessarily the interruption in heating during defrost that I’m concerned of. It’s more that it seems the heatpump goes into defrost a lot more often than would seem to be necessitated by conditions. I mean, twice in a half-hour period really seems far too often, especially given that the conditions, while cold, aren’t wet, frosty, misty, etc.

Sorry for the threadsit. I’ll go sit over there and be quiet now.
posted by Thorzdad at 2:16 PM on November 12, 2018

It’s more that it seems the heatpump goes into defrost a lot more often than would seem to be necessitated by conditions.

Only real way to judge that is to sit and watch the outside unit and see whether it's going into defrost before you see frost start to appear.
posted by flabdablet at 6:53 PM on November 12, 2018

Best answer: More expensive heatpumps have on demand defrost but other units defrost on a timed cycle. I have an Amana heatpump that has DIP switches on the control board on the outside unit that controls the frequency of defrost cycles in 30 min increments. You need to find your unit's owners' manual.
posted by LoveHam at 8:26 AM on November 13, 2018