chemical refrigerant like smell after new heat pump goes into defrost mode

chemical smell from heat pump



I have a new Trane heat pump and air handler. Installed in April, During the summer it was great. Now that winter is here there is a chemical smell. Here i what happens : heater is running all is good. when it is really cold the compressor makes Whooosh sound then some other noises. I assume this is defrost mode. Then after a few minutes cold cold air blows from the vents with a strong chemical smell. NOT dirty socks, Not moldy, in fact the opposite. A clean sanitizer smell or I associate it with the smell of an old freezer that needs defrosting along with a strong steam smell. The installer has been out and then a repairman. It would not do this while they were here, and they claim that thee are no signs of problems. The cold air is so cold and last for so long it defeats the entire work the hot air has done and the smell is so strong I worry what am I breathing. The last guy made it go to defrost mode, and the compressor made the noise, but the smell or cold air never did happen. It is not a dirty sock smell, not a bad smell, it is more of a metallic chemicall smell. In a new car when you go from heater to air conditionar... it is close to that smell.... I have googled for weeks..... and since it is intermittent...other than getting the repair guy to move in with me I am at my wits end....

 

Since the difference between a defrost cycle and running as an AirConditioner ( which you said was just fine) is that some auxiliary heat is turned on to reduce the coldness of the cold air produced maybe the Auxiliary heat is somehow the culprit.

If you run the unit in EmergencyHeat mode, so that the heat pump is not involved, does the smell appear ? If so perhaps there is some contaminant on the heater that is boiling or burning off ?

 

no, when I run straight aux. heat I do not smell the odor. In fact. it seems the more I run aux. heat then go back to heat pump the less it happens. Night before last and yesterday it did it about every three hours. Late yesterday I ran the aux heat for about an hour then back to heat pump and it has not happened again. Same outside temp, same indoor thermostat setting. Only difference is it may not be as humid today as it was yesterday and night before(no sleet or rain falling). I would almost say that when it happens it is at the very end stage of defrost mode. I am keeping track of when it happens, it has been almost 24 hours now. Last time I ran aux heat then back to heat pump it stopped for a while too but the weather also warmed up. But that is not the case this time.. Still under 32degrees outside, still sleet/ice on the ground, thermostate still set 68-70. So we shall see. I did call the salesman and talked to him about it yesterday. He said he will get with his boss and see. I understand intermittent issues that they can not reproduce. I have found some post that sounds like my issue but none of them have answers or they found it was a dirty filter and that is not the case.

 

It definitely sounds like oil burning off the re-heat coils but by now it should be dissipating.

 

ok, so oil from when it was made? oil as in leaking? how long should it take to burn it off? I bet it has only been used a few weekends while it was cold enough to go into defrost mode? I have been all day and it still (knock on wood) has not put off the smell again, I also have not heard the louder thunk whooosh a often as I was. Maybe it just needed time to break in? I am anxious for this cold snap to end.. and anxious to see if it comes back during the next cold snap. I live in North Texas, it is not like we get this cold this often.

 

Sorry.... let me clarify. They put oil on the heating coils to keep them from rusting. After several heating uses... the oil is usually burned off and the smell disappears.

 

eOk. so still below freezing. The unit did his all night Thursday night and most of Friday. Then I went all Friday evening and all Friday night. All day Saturday. I was so happy.. YEAH. The last night at 3am. I heard the unit do the louder than normal (shutting off/going into defrost mode) and then it came. Strong cold air (for over 5 min) and the smell.. I got up, put it on Aux. heat and went back to bed. I just now moved it back over to heat pump. &^%$$&*$#$#$%^&* not fixed yet. but may be getting weaker and less often. I asked the salesman. Since it is intermittent, Is there a device that can put close to my vents to measure or read what is coming out. To either leave up there and it just run or for me to hold up there when it does this? He said he thought there was, but that would mean they would have to leave it with me. Any suggestions on how I can "prove" that this is happening and to test to see if the smell does in fact have chemicals in it?

 

We have lived in our house for over 7 years. Our house is only 11 years old. Well, our heat pump went out about half of a year out of warranty. It was an Armstrong air 3.5 ton. I spent extra money, and paid for a trane. 15i and they installed a variable speed air handler. This occurred at the end of February. Not one problem, until it was really cold and raining the Sunday night before thanksgiving. The smell was awful! It woke me up that night every time. I called the people I bought it from. They sent a guy out at around 4:00pm on a day where temps were around 45-50. He couldn't find anything. He told me it couldn't be dirty sock because we did not have copper coils. He tried to say the smell was coming from the drain sucking sewer smell. I tried to explain it wasn't sewer smell. So, I poured some water down the drain in the unfinished basement, and no problems. Or so I thought. It got ow freezing, and no smell. Then, it started to snow. It was bitterly cold, and BAM, the smell was back. I went downstairs and noticed it was going through defrost cycle. The guy tried it make it go to defrost, and he said I would smell it right away. Well, I removed the cover, and almost got knocked down by the smell.
I describe the smell like a freezer with dry ice, old smell. I paid a lot of money, and now I get an efficient stinking heat pump. I hope the smell isn't permanent this coming summer. I have called 3 times, and no one visits. There is snow on the ground, with more freezing rain expected. They claim they are working on people with no heat, and my problem is next. We will see. I am going to show this post.

 

When it gets really cold and the heat pump can't keep up with the demand..... the electric reheat coils turn on.

When the unit goes to defrost.... the electric reheat coils turn on.

The smell of the oil burning off the coils can be pretty nauseating but I wouldn't necessarily call it an old freezer smell.

If this is a continuous problem.... try turning off the large two pole breaker that controls the electric heat coils. There may be a disconnect switch right on the air handler. You don't want to shut the system down or turn the air handler off.... you just want the electric coils to not operate. With the coils not operating you can see if the problem still occurs.

 

I used to set the thermostat to 68 at night, and then 70 when we wake, and then 68 when we leave for school (both teachers), and 70 when we return at 4:00. I have seen on the thermostat when it asks for auxiliary heat. It never stunk last year. I was so mad, I ran it on emergency heat all night, and no smell. So there goes the oil theory.

 

I was under the impression the new unit was installed just this past February. I had figured since the bulk of the cold weather had passed by that time that you hadn't needed the electric coils until Thanksgiving.

I can't offer any other thoughts on the smell at this time.

 

Maybe it's somehow outdoor odors; I think of how readily a passing skunk or a neighbor burning trash is detected inside my closed house .
Is there any air drawn in from outdoors either deliberately or accidentally ?
When in defrost have you ever gone out and sniffed the steam or water drippings - and just the ambient air for that matter?

Did you have any new duct work or plenum installed with the new system or duct cleaning ? ... maybe the smell is from sheet metal or some of the newer duct sealants or tapes.
I had the experience of intermittent metallic odors a few years ago after getting my ducts cleaned (a big mistake by the way).

I know you said it worked fine during the AC season, but maybe running the AC, suffering the cold air for a little while, would perform the defrost without the AUX heat (which seems to be ruled out) to see if you can cause the condition.

Have you tried removing the air filter when the smell is present ?

Have you examined the indoor coil and attached plumbing, insulation, drain pan for odors, debris, oily film, installation trash ?

Do you have an electrostatic filtering system ? A humidifier ?

 

Our house is tightly sealed, all electric. No air should be entering. The service man came and inspected the unit about a month ago. Everything looked new still. I keep a high quality filter changed every other month. And, it doesn't look that dirty. He claims he has never seen this on aluminum. He was going to visit Monday, but, I called and asked him to come some other time. The temp was up to 63 yesterday. And, it seems that he makes it over when it is warm. He said he would come when he can force the unit to defrost for a longer length of time. He still swears it is something else, but I know when I smell it. As for running the AC, warranty says not to do so in 60 degree temps or less. I will keep everyone posted. I wish I had a way to record smell. Maybe there will be an app for that someday.

 

I have the same problem. I'm not an HVAC person but I've been looking into this for quite some time. If the e-heat does not kick on after going into defrost mode than the whole system will rapidly cool down creating condensation in the duct work. If it's not new duct work it's going to smell. And not dirty sock smell. Mine is a wet metallic or wet drywall smell. Check to see if you are getting a significant temperature drop from the registers during defrost mode. Especially on a cold nite.

 

Having the indoor coil temperature change rapidly might be causing the odor.

If the odor is due to dust/dirt, it might get worse as the heatpump ages.

If it's due to a coating on the coil, it should get better.

I don't know what the solution would be.

 

the smell is so hard to describe. My son said it smells like a sanitizer. I have the head service guy coming in the morning. He is bring a detergent strip that is in this unit for me to smell to see if that is what I am smelling. The freon is still full so it is not freon I smell. I say it is the same as what soonerskins is smelling. It is like an old freezer that needs defrosting and then add a steam iron to that. I say it blows way way too cold of air during this time as well.

 

The repair man did come on Monday of this week. It was below freezing. He made it go to defrost, and wham! The smell was there, and he could not deny it. So, he cleaned the coils with some bio stuff. It hasn't smelled since, but, he made it sound like it would be back. He told me he has been in contact with the tech, and this was an environmental issue, and not a Trane issue. But, he said that they would get a new coated coil, and he would be back with me on an install date. He said I may have to pay labor, but he said the owner very seldom makes the customers do this.
It is interesting that Trane is so willing to change out the coil. They know something isn't right. But, since I paid for the Trane name, they are taking care of me. The repairman told me about a goodman unit, and the manufacturer would not replace the coils because they were not leaking. So, in my case, you get what you pay for. I went with a company with a reputation and a unit with a reputation, and it is paying off.

 

My repairman just left. He said there was a wire lose in the air handler and that is why it was blowing so cold of air during defrost mode. (forgot to ask they why did it work when I manually turn on emergency heat, but maybe different switches).. The unit did produce the smell, it was faint, but he smelled it. He immediately said that is dirty sock... I let him know real quick that I have never smelled a dirty sock that smelled like this. When I said at first I assoicated it with salt water, he said yes, he thinks some smell more of a brine smell then dirty BUT it call all smell different from one home to the other, BUT that was by far dirty soc smell. According to him Trane makes him coat it twice before they will replace. He said they do not do it to all the units at the point of manufacturing since it is expensive and only happens in about 10% of the units. And due to the cost they require him to coat it twice but that this only works in less than 10% of the time, so he coated it, if it smell comes back, he will coat again and if the smell comes back Trane will replace with different type of coils. I say we need to rename DSS but it is a relief to know I am not breathing freon. He laughed when I said it smelled like a chemical reaction.. cause it is.. reaction with heat and bacteria. Suggested to clean with Oxy type cleaners instead of bleach based cleaners. So, it looks like Soonerskin and I have the mystery solved... Now to really solve it.

 

I'm very interested in this thread as my heater has just recently started doing this exact same thing.

This is the first time i've been to this website but googling "weird smell from heater" mostly brought up stuff about how it usually smells when people first turn their heater on. This is different, it's exactly how you two have described it: When the defrost comes on the air blows way too cold and there's this weird, freezer/chemical smell.

I'm glad to know it didn't kill either of you lol. I was really afraid it might be something poisonous. I'll try to put what I've read in this thread to use but so far it basically seems one of you just had his coils worked on and the other had a wire loose? or something like that..

Gonna read over all this again.

 

I have the exact same thing going on with my Trane XL15i, which is just 2 years old. The defrost cycle starts, the cold air comes out of the ducts and a strange smell prevails. This is not a dirty sock problem. This unit has been worked on three times since I have had it. Never again will I buy a Trane. The AC part is fine but the air handler is too loud when running the heat. I wake up every time it comes on. What is the premium air flow without living in a wind tunnel?

 

well, what he told me does not make sense// smell due to heat over coils, but lose wire was not allowing the ex heat to come on? but for almost a month I had a wonderful no noise, no smell heater. Dec 3rd, got cold and damp and sure enought THUNK WHOOSE... then the cold, then the smell. I had the tech come back treat the coils and make sure that wire was not lose. I will be calling them as soon as I can and let them know, now the smeall is stronger and seems to be happening more and more and the ice cold air is back too... UGH>> So pissed off on this issue

 

The first thing the tech should resolve is the AUX heat not coming on. That should be easy for a good tech. Post the model# and I might be able to help him.

 

ok so he said the aux heat was not coming on due to a broke wire. said it could of broke when it was being installed by the tech tightening it down too hard. I swear when he left that day my unit ran GREAT, no loud noise before defrost, no cold air coming out, no smell. from 12/28 till 2/3 it ran like it was a good unit. Now it it right back to loud noise, more of a DSS smell but still cold cold air. I am going to call them and tell them I want a warranty exchange, I dont believe it is DSS and I certainly know it is not operating correctly. I also want him to show me the wire that was broke. oh it is a TRANE XR15 model number 4TWR5036g1000ab air handler: TAM7aoc36h31sbb. If they refuse the waranty replacement then I am going to tell him I am calling a competitor to come check out the unit and then go from there. i swear after he was there and "fixed the wire" and assured me it was DSS... if I had not been there I would of sworn he traded out the unit and gave me a new workign one... That is for about one month. LOL I am so beside myself with it. I really think I breathed chemicals for months and just know this is not how it is suppose to be.

 

If the electric heat hasn't been on for awhile and it suddenly comes on then some dust will be on it and it will burn off and that will smell briefly. I would make sure they didn't forget to put a filter in it.Even so, you might get that burned dust smell if the electric heat hasn't been on regularly. The smell won't last a long time and will dissipate but if more dust gets on it the same thing will repeat again.

Since this happened way back in Nov 13 or before hope you got it all taken care of.

If you use an add on humidifier or if your humidity there is high the coil could be loading up with moisture and then burning it off suddenly. The humidifier should always be upstream of your unit and not feeding into the return. The defrost mode will attract any high humidty that is there if defrost is a long time.

Most recent heat pumps allow for an adjustment of defrost times. You might be able to shorten defrost especially if you live in a more moderate area.If you can shorten defrost time and make the defrost at longer intervals you will save money.

 

Lorac, I experienced the exact same problem with my relatively new Trane XL16i system. The smell was exactly as you described it (more chemical than dirty sock). I first encountered the problem in Nov 2013 and contacted the contractor who installed the system. The contractor did not seem to have any knowledge of this type of problem and I let it go for another month or so. I also called the Trane Customer Support line and they also denied any knowledge of this type of problem. Finally I had a technician from the contractor come out to experience the odor which he was able to do by putting the system in defrost. He acknowledged that the problem was caused by the coils in the internal system which had also been replaced at the same time as the heat pump. He stated that in his 20 years of HVAC work he has only seen the problem about 5 times. He assured me that Trane was very well aware of this DSS issue and they would replace the coils at no cost. Two days ago my contractor showed up with a new coil which he replaced in about 2 hours at no charge. The new coils looked like they had been treated with something since they were a completely different color (black) from the original coils. So far so good though I can't say for sure if there have been any defrost cycles since weather here has warmed up a bit.

 

So any definite reason/solution to this cold air at defrost and chemical smell problem?

I think my system is doing it as well. It does not seem to smell like DSS, more chemical.

 

This unit has always smelled weird like dry ice when it's super cold but the heat seems to be working fine so I'm leaving it alone.

 

We had a new Trane XL18i installed this past spring. We have a strong chlorine like smell from it now that the weather is turning much colder. We'll be calling the installer on Monday. I initially thought it was the new heating elements and it would eventually burn off....not so.

I would definitely not call it dirty socks unless your feet sweat chlorine!!!

We also have the newer electronic filter. So, I don't see that as the issue.