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darthsmozers 04-23-2012 07:45 AM

FROST on HVAC?
 
2 Attachment(s)
Hi all,

This morning I noticed frost on some of the pipes that run out of the HVAC unit and into the wall behind it. 2 photos are attached.

It might be worth mentioning the reason I looked was because the air vent made an odd sound this morning. We ran the heat last night because of the cold rainy weather. We set it to 70. When we left this morning I lowered it to 65 since we won't be home. After I lowered the thermostat, which temporarily turned the heater off since it was already at temperature, it made a hard mechanical sound when shutting off. That's what prompted me to go downstairs and look in the laundry room and I found the frost.

Even in the winter I never noticed frost on the pipes. Can you take a look at the photos and let me know your thoughts on it? It seems strange to me, particularly since it wasn't below 40 last night outside.

Thanks!

Doc Holliday 04-23-2012 08:21 AM

IMMEDIATELY TURN THE SYSTEM OFF.

Systems freeze up due to lack of air flow/air flow being restricted (dirty filtr/clogged evaporator coil) and/or lack of refrigerant. Keeping the system running you'll stand a chance of blowing both the compressor and the fan motors (not to mention no one can work on a frozen up system).

You need to call and hire an hvac company.

ben's plumbing 04-23-2012 08:23 AM

Quote:

Originally Posted by darthsmozers (Post 905241)
Hi all,

This morning I noticed frost on some of the pipes that run out of the HVAC unit and into the wall behind it. 2 photos are attached.

It might be worth mentioning the reason I looked was because the air vent made an odd sound this morning. We ran the heat last night because of the cold rainy weather. We set it to 70. When we left this morning I lowered it to 65 since we won't be home. After I lowered the thermostat, which temporarily turned the heater off since it was already at temperature, it made a hard mechanical sound when shutting off. That's what prompted me to go downstairs and look in the laundry room and I found the frost.

Even in the winter I never noticed frost on the pipes. Can you take a look at the photos and let me know your thoughts on it? It seems strange to me, particularly since it wasn't below 40 last night outside.

Thanks!

doc is right on..air flow or low charge...shut it down ..check filters..let it thaw out....if you don't know how to check charge call in a pro..:yes:

darthsmozers 04-23-2012 08:28 AM

I did notice yesterday the thermostat had a little message on it that said "replace filter". I was going to do that today - it wasn't urgent to me since we haven't had the heat running except for last night due to a rainy night. Maybe I should have listened? :(

M3 Pete 04-23-2012 02:25 PM

Quote:

Originally Posted by darthsmozers (Post 905257)
I did notice yesterday the thermostat had a little message on it that said "replace filter". I was going to do that today - it wasn't urgent to me since we haven't had the heat running except for last night due to a rainy night. Maybe I should have listened? :(

a lot of thermostats show "change filter" on a time basis, like every 90 days. So it might not be a measurement of flow.

But it can't hurt to change.

darthsmozers 04-23-2012 02:42 PM

What is it exactly that would cause it to freeze due to lack of air flow? In other words, if its not freezing outside, how does the pipe become cold enough to freeze like that when the heat's running? (I know nothing about how the system works - new homeowner of less than a year). Is there a refridgerant that is kept warm when operating normally but freezes when not?
Forgot if I mentioned - the system is less than a year old (as is the whole house) and the heat is made via a heat pump.

Doc Holliday 04-23-2012 02:58 PM

The refrigerant is grabbing the moisture in the air which freezes at 32 degrees. Refrigerant only get's cold enough to do so in a contained system if it's low as it's under far less pressure in the lines allowing it to be extremely cold, well under 32 degrees.

Everything refrigerant related is pressure/temperature related.
At 57.5 psi refrigerant R-22 is 32 degrees, freezing. I'd suspect your system has less than 57.5 of pressure on the remaining refrigerant it has left. An "average" amount of pressure would be 75 psi, which would mean the temperature of the refrigerant is 44 to 44.5 degrees f.

It is not uncommon for a system to spring a leak.

http://www.advantageengineering.com/...%20shading.jpg
For more information on refrigerant temperatures and pressures
call the Advantage Service Department at 317-887-0729.

darthsmozers 04-23-2012 03:12 PM

Doc,

So are you saying that either 1) I have a refrigerant leak or 2) The old air filter could be the problem? If I replace the filter when I get home from work today and see no more frost, can I assume all is well?

Doc Holliday 04-23-2012 03:20 PM

Yes, leak and or blocked filter. Concerning the filter, dirt can find it's way past the filter and through any possible air leaks in the system, many times a return air leak, and build up in and on the evaporator coil, used for both heating (it's actually a condensing coil during heat but evaporator in cooling, one and the same) and cooling in a heat pump application. You can try changing the filter and if indeed it is very dirty than you may need to have your evaporator (coil inside the home, the easy explanation) coil cleaned as well.

Doc Holliday 04-23-2012 03:21 PM

You'd need refrigerant gauges to check the pressures of the refrigerant in the system, to tell if it's low.

darthsmozers 04-23-2012 03:32 PM

Quote:

Originally Posted by Doc Holliday (Post 905586)
Yes, leak and or blocked filter. Concerning the filter, dirt can find it's way past the filter and through any possible air leaks in the system, many times a return air leak, and build up in and on the evaporator coil, used for both heating (it's actually a condensing coil during heat but evaporator in cooling, one and the same) and cooling in a heat pump application. You can try changing the filter and if indeed it is very dirty than you may need to have your evaporator (coil inside the home, the easy explanation) coil cleaned as well.

OK I will check this afternoon. Here's hoping its just the filter! I will report back. Thanks! :thumbsup:

beenthere 04-23-2012 04:23 PM

Is it a heat pump? Had to be running in cooling mode to freeze the indoor coil. or it got stuck in defrost mode.

darthsmozers 04-23-2012 04:54 PM

2 Attachment(s)
So I pulled out the air filter and ice came out with it. See first picture.
I tried sticking the camera inside where the filter goes to take a photo of the ice, but I can't tell what I'm looking at. See second picture.

:(

M3 Pete 04-23-2012 05:26 PM

Quote:

Originally Posted by darthsmozers (Post 905647)
So I pulled out the air filter and ice came out with it. See first picture.
I tried sticking the camera inside where the filter goes to take a photo of the ice, but I can't tell what I'm looking at. See second picture.

:(

is all the white stuff ice?

The HVAC pros can tell you better, but that looks like your evaporator coil under all that ice. Has your A/C been on?

Doc Holliday 04-23-2012 05:41 PM

Your filter doesn't look too bad but you should've turned off the system last night and left it off. It would have thawed out by now, enough to add refrigerant and/or find the leak. It could not have frozen up today unless it was running.

I'd be willing to bet you have a leak. At this point it's best to call an hvac company to resolve this issue. Working with refrigerant requires special licenses and special tools.


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