New HVAC flex ductwork new plastic smell

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Old 09-21-19, 06:46 AM
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New HVAC flex ductwork new plastic smell

About a month ago we had a new AC handler and new AC ductwork installed in our home. Since then we have had a new plastic smell coming from some of the vents. The smell is similar to when you open a new plastic shower curtain or new pool float. The ac company said the smell is coming from the plastic lining that is used in the flex ductwork. The maker of the ductwork has stated that is not possible since they use PE plastic and PE plastic does not off gas in anyway. We were okay with the smell when it was first installed but after a month I would have figured the smell would have gone away. Any ideas? Could it be the plastic lining? And if so, are the off gases hazardous? Could some of the ductwork be defective, which is why only certain vents are effected? The ac company inspected the entire system yesterday and cannot find the source. They were thinking that there might have been an incomplete seal causing some of the mastic to remain wet and produce a smell. But they found no leaks and all the mastic appears to be dry. They are coming back out on Monday to cut into the duct board boxes to see if they might be able to locate the source.
 
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Old 09-21-19, 08:17 AM
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Flowers and food have odors, and those odors aren't hazardous. A toilet can often smell so bad you need to turn on the fan or light a match. Also not really hazardous. True, there are some odors like formaldehyde or chlorine or other chemical / noxious gasses that are hazardous, and make people sick, but I doubt this is one of them. It's no different than that new car smell or new carpet smell. But I have learned that some people- especially nowadays- are more sensitive to odors than most. Most would just shrug it off and not let it bother them. It makes others go berserk because it's all they can think about, and they convince themselves it's going to make them sick. Sometines it may depend on which type of person you are.

I have heard similar complaints, though. Is it an ammonia type of smell? Can you describe it?

Opening a window or two a few inches to exchange air, might help speed the amount of time it takes for it to go away. But it will eventually go away, I'm sure. Until then, get some air freshener or scented candles to mask it if it bothers you that much.
 
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Old 09-21-19, 11:08 AM
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Rarely does that smell linger. I don't install..... just service systems but I can sometimes smell the plastic. I have noticed that if the lines are run thru a hot attic..... that can accentuate the smell too.

You could try leaving your system in "FAN ON" mode for a week or two to air out the lines.
 
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Old 09-21-19, 02:12 PM
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Find out why ." only certain vents are effected"..... is the key.
 
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Old 09-21-19, 04:46 PM
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Xsleeper, the smell is not an ammonia smell, it is a new plastic smell. The best way I can describe it is similar to opening a new plastic shower curtain or plastic pool float. It has that same plastic like smell.
 
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Old 09-21-19, 04:50 PM
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PJmax, yes the duct work goes through the attic and I have noticed the first blast of air in the afternoons is very strong with the smell. It thins out after awhile but never goes away. We have been running the ac constantly for 4 weeks now and the smell has not lessened which has us concerned. You would think if it was an off gas it would be decreasing a little bit each day.
 
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Old 09-21-19, 04:53 PM
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clocert, yes I think you are right in that finding out why only certain vents are effected should hopefully lead us to the answer. It is such a weird situation and it has left everyone wondering why might be going on. It is a shame because we got rid of the old duct work/ac because of mold/mildew and now we are dealing with this. You do not expect a new system to possibly be causing the same health issues the old one was causing.
 
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Old 09-23-19, 06:31 AM
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Have them install a plasma air unit. Something like the Iwave iWave-R - Air Purifier
 
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Old 09-23-19, 03:18 PM
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Update: The ac company was back out at the house today with a different tech. This tech noticed that not all boots were sealed completely in the attic. He believes the air is coming from the attic and is giving a plastic smell. They are coming back out on Wednesday to reseal the boots. I am not 100% convinced. The attic doesn't smell like plastic (I have been up there crawling around more times then I can count lately). But I am going to go with their assessment and see if it changes the smell coming out of the vents. If not then it will be back to the drawing board.
 
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Old 09-23-19, 03:35 PM
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As I mentioned..... the smell increases with heat so a poorly sealed flex line in an attic could expose it to more heat then it should. It may be that the inside duct is sealed but not the outside insulated part.
 
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Old 09-24-19, 01:25 PM
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PJmax, thank you, that makes a lot of sense and that gives me hope for tomorrow's possible fix!
 
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Old 09-26-19, 03:00 PM
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The ac company now thinks that the ac handler coils might have some glue, from the factory, on them which could be causing the smell. They are going to send a tech out tomorrow to clean the coils using a sanitation/cleaning fluid. Has anyone heard of this happening before? I am confused as to why the glue smell would only come out certain vents but I am willing to have them try it to see if it works.
 
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Old 09-27-19, 09:08 AM
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There are some people that have had problems with the coils in their heat pump systems. Some called it a dirty sock smell. It was caused by the bacteria in condensation reacting to either a coating on the coil or the metal of the coil. I don't recall anyone mentioning it smelled like plastic. Most said it smelled like a locker room. I'd imagine there are varying degrees of this problem.

You can search for dirty sock smell heat pump. Many articles on it.
To the best of my knowledge..... it only affects heat pump systems.
 
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Old 09-27-19, 01:52 PM
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The ac company was out at the house today and the sprayed the coils. It didn't help. They are going to come out next week and replace the spare bath line to see what that does. I am hoping that is the answer because I cannot figure out anything else that would be the culprit. I smelled the tape and adhesives they used to create the boxes. None of them had the same plastic smell. The tech did mention the clear condensation pump line. It is made out of clear plastic and does have a plastic smell. I am not sure how the condensation pump works and if the smell of the plastic hose could infiltrate the system. If that was the case I would imagine it would effect the whole system and not just some vents.
 
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Old 09-27-19, 07:28 PM
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The condensation line would not cause a smell inside the duct. That small hose is just used as a drain line from the pump to a sink, etc.

That's interesting..... you only smell it now in one room ?
 
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Old 09-27-19, 07:52 PM
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If everything else fails, You can do the following: Shut down or close all bad vents, replace the duct for that one vent, once that one is fixed, then do all others. Since you already know where (which vent) the problem is, I don't think it is that hard to fix. Good luck.
 
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Old 09-28-19, 03:55 AM
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Pjmax, thank you, that helps us rule out the pump. The smell is coming out of 5 vents. The spare bath line is the strongest smelling one and I am hoping on Monday they will replace that line to see if the smell in that vent goes away. If it does than we will know what needs to be done for the rest of the effected lines.

clocert, thank you, yes I think that will be our best bet! Hopefully that will work, because if it doesn't I do not know what else we could try. It seems to be the only viable option.

I have uploaded a diaphragm I created of the duct work in the attic. The black boxes are the duct board boxes they created. The green lines are larger flex duct lines that join the boxes. The red lines are flex duct lines that have the smell. The blue lines are flex duct lines that do not have the smell. The yellow lines are the return lines.

 
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Old 09-30-19, 02:26 PM
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The ac techs were back at the house today. The replaced the spare bath duct line and the smell went away! I am still not sure why. I smelled the duct work they removed and I smelled inside the box that was connected to the spare bath line. I smelled the boot that they created using duct board and there was an odor to it. It didn't match exactly the smell I was smelling but it was close. They said they used spray adhesive to create the boxes and I asked them not to use it when they made the new boxes. I am not sure if that was the change that made the difference but I am happy nonetheless that the smell is gone. They are going to come out tomorrow to change out the rest of the effected duct lines. I have my fingers crossed that the change solves the problem for the rest of the ducts. I asked the ac techs why only certain vents would be effected if the same materials were used for all the vents. They said they had 3 techs creating boxes that day. Some may have used the spray and others didn't. I am not sure why the spray adhesive is still giving off such a potent smell 5 1/2 weeks after the install. Have my fingers crossed that we can finally have our home back tomorrow!
 
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Old 10-01-19, 08:27 AM
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Make them use metal duct instead of duct board.
 
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Old 10-01-19, 01:40 PM
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I think something might have happened with the spray adhesive and the plastic lining. The techs also made a comment today remembering that it was raining when they installed the first set of boots. He said the boots might have gotten wet and that mixed with all the sprays, tapes, etc, might have created the perfect smell mixture. I am guessing if it was chemically altered that is why it never stopped smelling. The techs replaced all the effected boots and the smell seems to have lessened if not gone all together. The spare bathroom line that they completely replaced (boot and line) yesterday still has a bit of a smell, but I think it is new plastic liner I am smelling and not the same chemical plastic smell I was smelling before. The plastic liner has a smell that reminds me of raisins for some reason and that is what the vent smells like now. I am assuming that smell will go away with time. I am excited that the problem seems to be fixed. I am hoping it doesn't happen to anyone else but at least maybe they can use this troubleshooting information to do the same with their house. Thank you everyone for your advice, input and thoughts!
 
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