Foam smell when AC turns on | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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SPFer Posted: Jun 09, 2011 09:12 AM	Foam smell when AC turns on We sprayed a job about 8 weeks ago and the Owner just informed me of an odor issue. The smell only occurs when the AC turns on. The unit and ductwork is up in the attic, but the unit does not draw its air from the attic. I remember this being mentioned before in the forum but could not find it. Any thoughts on why the smell would only occur when the AC is on?
mason Posted: Jun 09, 2011 09:58 AM	A few things could have occured. 1. Some overspray fumes and mists could have drifted into the duct work and become embedded in the ducts insulation. If the foam was not completely mixed, some catalyst could have been absorbed causing odors when the unit is turned on. 2. Odors from the foam could be drawn into the units and circulated only when the units are on. You need to identify the source of the odors. Check out the foam, cut into it and see if it has an odor. Then check the ductwork and do the same. Repair is to remove the odorous foam or insulation. You might have to replace the ductwork if it's insuation is indeed saturated with partially unreacted foam.
angus mcdougald Posted: Jun 09, 2011 12:06 PM	what about trying to seal the ducts first?
Posted: Jun 10, 2011 03:46 AM	stick your schnozz up in the attic,,, should smell up there if the oder is in the attic and it is being "picked up" by the ac unit.. take a sample of your foam from the attic NOW. seal it up in a baggie,,, check it for oders in the am,,,the jimmie durrante test,,, keep it in the bag,,labled with job, batch, in case you need it later,,, ???if the ac unit does not draw air from the attic,,,one would question why this is the foam attic assemblies problem??? has anyone considered a deasd rotting bird/critter in the ductwork somewhere,,been there,,smelled that..(pulled a decaying cat out of an ac unit onetime,,,wedged into the squirrel cage,,,channel lock and piece at a time,,,yank & barf,,,yank & barf,,,) consider: 1) i have inspected my condtioned lid asssembly applied as contracted. i see no apparrent defects or inconsistencies in the appliction, nor do i detect any apparrent oders related to the foam system (there should be none) in the attic space. 2) the conditioned lid assembly is not the origin of the oder.(call the hvac man! its his assembly!) too many times the spf contractor becomes the dumping ground for any weirdness in the home cause its the "new" kid on the block,, sirbrightness had it too,,if it is from the attic (then ventilate the attic for a week or so and shoot someone elses closed cell foam next time cause the stuff shouldnt stink,,unless you kinda hogged it,,lol)seal the duct will lessen the chance of the duct pickin up the oder,,, good luck dude
mason Posted: Jun 10, 2011 02:10 PM	I agree with foamdude. Make sure the odor is from the foam first. Foam has a specific type of odor, like a slightly chemically rotten egg odor. Doesn't smell at all like dead rodents, formaldehyde or pesticide.

Author

Comments

SPFer

Posted: Jun 09, 2011 09:12 AM

Foam smell when AC turns on

We sprayed a job about 8 weeks ago and the Owner just informed me of an odor issue. The smell only occurs when the AC turns on. The unit and ductwork is up in the attic, but the unit does not draw its air from the attic.

I remember this being mentioned before in the forum but could not find it.

Any thoughts on why the smell would only occur when the AC is on?

mason

Posted: Jun 09, 2011 09:58 AM

A few things could have occured.

1. Some overspray fumes and mists could have drifted into the duct work and become embedded in the ducts insulation. If the foam was not completely mixed, some catalyst could have been absorbed causing odors when the unit is turned on.

2. Odors from the foam could be drawn into the units and circulated only when the units are on.

You need to identify the source of the odors.
Check out the foam, cut into it and see if it has an odor. Then check the ductwork and do the same.

Repair is to remove the odorous foam or insulation. You might have to replace the ductwork if it's insuation is indeed saturated with partially unreacted foam.

angus mcdougald

Posted: Jun 09, 2011 12:06 PM

what about trying to seal the ducts first?

Posted: Jun 10, 2011 03:46 AM

stick your schnozz up in the attic,,,
should smell up there if the oder is in the attic and it is being "picked up" by the ac unit..

take a sample of your foam from the attic NOW.
seal it up in a baggie,,,
check it for oders in the am,,,the jimmie durrante test,,,
keep it in the bag,,labled with job, batch, in case you need it later,,,

???if the ac unit does not draw air from the attic,,,one would question why this is the foam attic assemblies problem???
has anyone considered a deasd rotting bird/critter in the ductwork somewhere,,been there,,smelled that..(pulled a decaying cat out of an ac unit onetime,,,wedged into the squirrel cage,,,channel lock and piece at a time,,,yank & barf,,,yank & barf,,,)

consider:
1) i have inspected my condtioned lid asssembly applied as contracted. i see no apparrent defects or inconsistencies in the appliction, nor do i detect any apparrent oders related to the foam system (there should be none) in the attic space.
2) the conditioned lid assembly is not the origin of the oder.(call the hvac man! its his assembly!)

too many times the spf contractor becomes the dumping ground for any weirdness in the home cause its the "new" kid on the block,,

sirbrightness had it too,,if it is from the attic (then ventilate the attic for a week or so and shoot someone elses closed cell foam next time cause the stuff shouldnt stink,,unless you kinda hogged it,,lol)seal the duct will lessen the chance of the duct pickin up the oder,,,

good luck
dude

mason

Posted: Jun 10, 2011 02:10 PM

I agree with foamdude. Make sure the odor is from the foam first. Foam has a specific type of odor, like a slightly chemically rotten egg odor. Doesn't smell at all like dead rodents, formaldehyde or pesticide.

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