heat pump smell

deee_gwJanuary 31, 2014

We live in a 17 year old house. We replaced the original heat pump with a Trane this past summer. We live near the Georgia Florida border.

The air conditioning worked great. The heat works fine too but during this last bit of cold weather there has been an intermittent odd odor coming out of the vents. I believe it happens when the heat strip is on but it doesn't happen every time.

It's a stale and musty odor. It doesn't smell moldy or wet. The ducts were cleaned about a year before we installed the new unit and we didn't have the smell with the old unit. I've read about "dirty sock" but I don't think that's the issue.

I have a call in to the installers but I thought would post here and get some opinions and advice. Thanks.

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Of course I can't be certain. But I believe the clue to your issue is in your post. It is a new system. I suspect you are getting some residue burn off inside your air handler. If this is not making you sick and is more of an annoyance, I would not do a thing. Just monitor for the rest of the winter. If it doesn't go away by then, call your installer for a look see.

Since this is a new system, I really doubt you have dirty sock syndrome.


    Bookmark   January 31, 2014 at 7:33AM
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We have a year-old Trane gas package unit, and it seems we are also potentially dealing with dirty sock syndrome. We have been trying to figure this out for weeks, even had a plumber come out thinking it was a drain issue, but it's definitely coming from the vents. No leaks in ducts. The guys were out here today.

They cleaned the coils today and told us to monitor. If it's not better, they may have to replace the coils. Of course, it's jut out of the 1-year warranty, but we will argue about that. A unit that cost this much should not have problems one year out!

We are in the Carolinas, so definitely been a cold, wet winter.

This post was edited by gsciencechick on Mon, Mar 17, 14 at 14:07

    Bookmark   March 17, 2014 at 2:06PM
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Keep in mind that all ducts leak, it is just a matter of where and how much. If the leaks are external to the house envelope, you get pressurization or depressurization of the house. The depressurization can suck air in from outside in unpredictable ways.

You won't have DSS after you've been in heating mode for any length of time.

    Bookmark   March 17, 2014 at 2:20PM
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We started noticing this over the holidays. It is moreso when the system has been off for awhile. For example, on Sat we turned it off since it was in the 70's. I have horrible smell, and I could smell it in the late when the heat went back on. This morning when the system had run during the night it was OK.

    Bookmark   March 17, 2014 at 3:20PM
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Happy to report their treatment seems to have helped. We had the heat off since yesterday afternoon, and putting it on in the morning there was no smell.

We also had some plumbing work done the other day in the crawlspace, and I think that was also contributing to the smell. The smell was very strong after the guys left.

    Bookmark   March 21, 2014 at 9:44AM
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What "treatment" did they do?

    Bookmark   March 21, 2014 at 10:35AM
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Yes, we are still having this problem. They put some sort of "cleaner" on the coils. The tech said it should help, and we should not be getting the smell when we run the A/C. We are still getting the smell with the A/C except now it smells like must and cleaner! It's like a Comet/Ajax smell

They said the only thing to do would be replace the coils, but it the heat isn't running, it can't be the coils, correct?

We are ready to call out a different company for a second opinion. We are beginning to think it's the ductwork.

    Bookmark   April 13, 2014 at 7:35AM
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All of you complaining about DSS (Dirty Sock Syndrome) should google Dirty Sock Syndrome and spend two hours reading about it. It does exist and Trane knows all about it. Problem is in the coil, copper pipes and aluminum fins in the newer hi efficiency models build up bacteria around the coil and give off a odor that can bother those who have a sensitive smell condition. My wife has a very sensitive smeller and continuously complained to me about the odor that I did not smell. After researching DSS I was convinced that was the problem and had the coil on my one year old system removed on April 11 to be sent off for a cleaning and coated with a epoxy that should eliminate the problem. At the date of this thread we have no odor, also no A/C, but the problem has been identified and is in the process of being fixed. My contractor has worked with this problem previously so it is not new to him. Update to follow after coil is reinstalled.

    Bookmark   April 14, 2014 at 4:16PM
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Kodak.1, in your research, do you see many reports of DSS when heat pumps are in the heating mode?

    Bookmark   April 14, 2014 at 6:08PM
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ionized:, I my case my wife smelled it when it was off or on. I've read some smelled it when you switched from heat to cold air. If you read all the articles on the Web you see some smelled it during the defrost cycle which only applies to the outside unit. I can only say, since the coil is out, my wife is not having the breathing problems she was having, and I am relieved. I do know Trane MFG is aware of the problem. Some folks have installed UV lights in the return air pendulum to clean the air and had good results.

    Bookmark   April 14, 2014 at 6:51PM
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FYI: The defrost cycle also applies to the inside unit. It switches the system into cooling mode so that the outside unit gets hot and the inside unit gets cold. To keep your house from freezing, it also activates the electric heating coils. After a few minutes it switches back.

    Bookmark   April 15, 2014 at 12:45AM
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Thanks, Kodak. I have been OOT the past couple days not online here. We have read some on DSS but could definitely read more. It will be interesting if your treatment helps. My DH is the sensitive one, me less so. However, I can smell it when I first walk in the house.

Major OOPS: Our system is a Lennox gas pack, not a Trane, but I'm sure the same problems exist. Our unit is exclusively outside; that is how everything is in our neighborhood.

I am almost thinking about contacting our local company and seeing if we can get a Lennox rep out here. I remember when we bought the system they offered to install the UV lights as an option.

We had a Goodman which is not considered a great brand, but it never smelled ever. The gas furnace portion is about the same efficiency as the old, so not that great.

    Bookmark   April 19, 2014 at 8:35PM
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It took awhile to get my coil back from Bronz Glow in Florida. It has been epoxyed and looks good. Installed today and already my wife can tell it does not have the odor it had before. Thank goodness for that. Amazing what you can learn by googling HAVAC odor or Dirty Sock Syndrome.

    Bookmark   May 14, 2014 at 9:27PM
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I don't understand why you'd have more severe DSS constantly in heat mode. One would think that the VOCs would blow off pretty quickly in heat mode and be gone as long as cooling is not used since no new growth will occur.

My understanding is that epoxy coating causes water to bead up and shed better. That would also tend to take soil with it. I am not saying that it is a bad move in this, but I wonder what it does to efficiency.

Too bad it would be too expensive to make an all-copper coil. The heavy metal would probably suppress microbial growth just fine.

Another theoretical solution to this kind of problem would be to blow outdoor air (filtered) through the unit when it is shut off for the day when it will not be run for several hours. That would dry the moisture out. I set up my car AC to do something like that.

This post was edited by ionized on Wed, May 14, 14 at 21:56

    Bookmark   May 14, 2014 at 9:54PM
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A+. You have the answer to the problem. The extent to which copper limits, when compared to aluminum, the growth of bacteria is 99.99 % and the limitation of fungal growth is 99.74 %. ("Characterization and Control of the Microbial Community Affiliated with Copper or Aluminum Heat Exchangers of HVAC Systems"; Michael G. Schmidt, et al., 2012. DOI 10.1007/s00284-012-0137-0)(last paragraph). In other words, the smelly stuff can't grow on copper.

They should have gone to all copper instead of all aluminum coils. But then they probably wouldn't have been able to make as much money and what's a few sick people.

    Bookmark   March 10, 2015 at 10:02AM
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