Heat Pump icing question

[lakelivin]

I've got about a 10 year old ComfortMaker heat pump. After a pretty cold night (mid-low 30's?) it got up to low 60's today. About 2:00 p.m. I hapened to pass by the outside unit and noticed that it was almost completely iced up (it has cooling fins around it, not the 'bristle' like coils).

Can anyone tell me what that likely means? (here's hoping not alot of money, 'cause that will really hurt right now).

 

[Limited-Time]

Re: Heat Pump icing question

Not a pro here but sounds like the de-ice cycle is not working. Have also seen them ice over due to low Freon, but only in the summer if I recall correctly.

 

[stevieray]

Re: Heat Pump icing question

Most likely cause is as LT says, bad defrost cycle. This could be any number of small, inexpensive electrical parts (thermostats, relays, timers). Could also be bad outoor fan motor or reversing valve. Turn it off, squirt it down with a garden hose to get the ice off & reset everything (switch off the breakers & turn back on). That may be enough to goose it back. If the ice comes back & stays, you may need to call for service. Don't let 'em sell you a new one without a second opinion - it may be just a cheapy part.

 

[Ron G]

Re: Heat Pump icing question

im no expert either but im with LT,also make sure the fan motor is running.

 

[lakelivin]

Re: Heat Pump icing question

Not the fan motor, that kicked on when I was out there. I'll have to pull out the multimeter & poke around tomorrow (too cold to start tonight).

 

[Ron G]

Re: Heat Pump icing question

could be the compressior(sp)i hope not.

 

[Boomyal]

Re: Heat Pump icing question

...also it could be that you caught it just before the defrost cycle.

 

[rickdb1boat]

Re: Heat Pump icing question

...also it could be that you caught it just before the defrost cycle.

Absolutely. It can last anywhere from a few minutes to 10 minutes...
That is normal operation in the heating mode......

 

[lakelivin]

Re: Heat Pump icing question

Well, ice was gone when I checked it a couple of hours later. Looked today & no ice (but there has been a light rain so that could have melted anything that was there).

Guess I'll wait & keep monitoring it to see if it happens again.

As far as catching it right before the defrost cycle, the ice was just about completely covering the fins all the way around the unit, in approx. 60 degree weather. Would a properly working deforst cycle let that much ice build up before kicking in?

Ron G- w.r.t. your last post, I'm holding up my index fingers in the shape of a cross, as if to ward off a vampire 8).

Thanks for the feedback & I'll post back if I catch it icing again.

 

[ob]

Re: Heat Pump icing question

The heat pump units that I am familiar with have a (freeze stat) located on or close to the outdoor unit fins that initiates a hot gas bypass valve.I suspect yours is defective or dislodged.This feature is designed to prevent the freezing over that you mentioned.Expanding ice between the coil fins and tubing can lead to rupture.One other note:Heat pumps are grossly inefficient under ambient temps of 32 degrees where they rely heavily on the supplimentary indoor electrical heat strip/s for temp control.Not to mention that the heat pump compressors are laboring summer and winter.

 

[Boomyal]

Re: Heat Pump icing question

As far as catching it right before the defrost cycle, the ice was just about completely covering the fins all the way around the unit, in approx. 60 degree weather. Would a properly working deforst cycle let that much ice build up before kicking in?

In view of that lakelivin, I'd pay a tech to come out and put the guages on it. They can also check out the defrost timer. Better now than to wait for the deep freeze.

 

[stevieray]

Re: Heat Pump icing question

As far as catching it right before the defrost cycle, the ice was just about completely covering the fins all the way around the unit, in approx. 60 degree weather. Would a properly working deforst cycle let that much ice build up before kicking in?

Normal frosting is a thin, powdery looking coating. Solid ice is not normal. Did it work OK the last time you ran the A/C in the summer?

 

[lakelivin]

Re: Heat Pump icing question

Didn't notice any problems last time I ran the A/C, but wasn't looking for any, either. Heat cycle has been working fine, but haven't had another really cold night lately either.

I'm gonna monitor it for now. Even if it completely stops on a cold night, I have a fireplace with a catalytic combuster (acts more like a wood stove than a fireplace) that will heat the whole house if I fire it up.

I'm aware of the limitations of a HP as it gets colder. But I'm in north-central NC; gets under 35 deg. but not for long periods of time. Overall, it's stil probably the most economical alternative for me (outside of geothermal or something exotic like that).

1500 sq. ft., 1.5 story cedar log house (stick built .5 second story), all electric utilities (heat pump, well), one person except for when family visits in the summertime. Monthly total electric bills range from around $50 (spring & fall) to max of around $180 (coldest winter & hottest sumer months)....

 

[stevieray]

Re: Heat Pump icing question

Didn't notice any problems last time I ran the A/C, but wasn't looking for any, either. Heat cycle has been working fine, but haven't had another really cold night lately either.

Reason I asked is if the compressor was going bad, you probably would have noticed it wasn't cooling right.

As far as heat, most have an aux electric backup that will kick in & heat the place even if the compressor is dead. Do you see an indicator light on your thermostat that says "aux heat" or "em heat" & is it lit all the time it's running?

 

[lakelivin]

Re: Heat Pump icing question

I try to keep the aux heat off (e.g.,slowly raise thermostat temp over time if I've been away & previously turned the heat down). I'm almost positive it hasn't been on, so no indication of compressor problem on that front. Knock on wood 8)