Odor during defrost on Trane

[Bentonville]

Being home more today and the outdoor temp being colder, I noticed my Trane dual fuel unit ( installed this summer) has defrosted more. We noticed a strong, almost sour odor when the thermostat showed stage 1 and 2 simultaneously, which is defrost. The air was blowing through the vents during this time and the odor is not so pleasant. It dissipated after a couple of minutes when the defrost cycle finished. I have mentioned this on another post before and was given good input as to the smell being sort of like opening a freezer. However, because of the strong odor, my wife asked for reassurance. Naturally when I contact my installer during the week, the unit is normal and everything is as it should be. it probably is but I would like to ask if this odor is normal. Thanks and I wish all of the great contributors here a Merry Christmas!

[tinknocker service tech]

no it isn't normal
trane has a method that seems to work well to solve this
special cleaner that is sprayed on the Eva coil while the blower is on and let to dry and done again just for good measure the a trane stay-cleen coating is sprayed on the coil with the blower on and let to dry and sprayed on a second time
have done this a few time and seems to work well
also recommend a UV light between the coil and the blower as to help kill any bacteria growth and prevent the odor from coming back next year

[dunkman]

Maybe there's something cooking on the electric heat strips? Try emergency heat and see if you get the smell.

[Bentonville]

Thank you for the input. I don't know if I have electric strips. The heat pump and natural gas are all the energy sources I know of in the unit. The smell is only with the defrost of the heat pump, as far as I understand. I was hoping it is something that will go away with time. During the summer months the defrost doesn't run so maybe it's a newness thing. However, I have sent my installer an email asking about the mold the other poster suggested. It makes sense to me. If you have any thoughts about this all, please share. Thank you.

[gravity]

if you switch the thermostat to emergency heat an let the furnace kick on does the smell come back? it could be something to do with the a/c running in defrost or maybe your smelling exhaust fumes from the furnace?

what type of furnace is installed. are the exhaust pipes hooked up?

[Bentonville]

Trane 16 SEER dual fuel system. The exhaust is a part of the unit as far as I know. The unit is outside and I don't see how exhaust can get in the duct system. I only smell the odor when the thermostat indicate stage 1 and stage 2 simultaneously. Steam rises from all the vents found all around the coil during this operation.

[gravity]

is this a packaged unit or a split system?

like a gas furnace in a basement with a h/p coil on top of the furnace?

[thermojohn]

This condition is classic 'Dirty Sock Syndrome'. We have dealt with it many times, but have not found the silver bullet yet. There are a lot of snake oil remedies, so research it out before you drop your dime.

Link provided explains the phenomenon, and many comments follow the article. My point here is to point out the condition, set the stage for education, and kindly step aside.

[Bentonville]

I will read the information. Do you know if it is dangerous or just unpleasant? I thought I did research before I purchased the system. Thank you for the input, all.

[thermojohn]

It's not dangerous.... Just odiferous. It's not brand specific, so don't be too hard on yourself or your installing company.

[Bentonville]

Man, it seems crazy. You spend thousands of dollars trying to buy the best system for your family and then something like this comes up. It seems that the mold and bacteria can be harmful in certain cases, according to some of the posts in the site you gave me. I have contacted my installer via email and hopefully he will address the situation. It seems that spraying is only temporary. Coated Coils seems to be the permanent solution. I don't have any idea how to accomplish that. I guess my installer will have to deal with it. Thanks for the information. I had no clue.

[tinknocker service tech]

what i axplained before is what trane will require be done first before they will do anything
if it doesnt work and the odor comes back then your installer can call trane and order an epoxy coil witch trane will supply
he has to do what i said first or trane will not do anything

[Bentonville]

Thank you very much, Everyone. Tinknocker, where is Supply? I live downeast in Stantonsburg. Last night the smell got bad so I just swithced to Emergency Heat. No smell but the system burned Nat. Gas. all night. I wonder if that heats up the bacteria enough to kill it?
I sent a copy of all of these comments to my installer and am waiting on his return call. Thank you all for your input. This forum is quite unusual in a world of rude folks. I appreciate how professional and how helpful the members are on this forum.

what i axplained before is what trane will require be done first before they will do anything
if it doesnt work and the odor comes back then your installer can call trane and order an epoxy coil witch trane will supply
he has to do what i said first or trane will not do anything