Anyone up for a good puzzle/challenge? We have a mystery smell that has been coming through our hvac vents for the last 5 months that just appeared after living in the house for 4 years and it’s getting worse, so bad I have the family staying in a hotel. The Smell is a musty cigarette/burning smell (similar to an old musty bar when they allowed smoking) but we don’t smoke, nor do any of our neighbors. unfortunately I can’t find anyone on google that describes a similar smell. Smell is in the air and we can’t trace it to any source Inside or outside the house. We have had multiple experts out and are $8k into solving this mystery with no solution. Hoping someone in this board has smelled this smell before /dealt with similar issue and can give some ideas to explore. We are getting desperate so really appreciate the help!
Equipment- forced air, 80% efficient gas Lennox furnace with Bryant ac unit, furnace is 5 years old, ac is 4 years old. Furnace is located in garage.
House: 2 story single family (removed from other houses)1990 built house located in the Seattle area. House has floor vents on both floors, a crawl space basement, and unfinished attic (no duct work in attic) and 3 returns, one on downstairs wall (north end of house), one in ceiling (south end of house), and one up stair son floor wall, that appears to actually not be a ducting to anything-looks like builder got away with this one.
What we have done so far: professionally cleaned the vents, had mold air test samplings throughout house (all negative), had crawl space experts inspect the crawl space, had multiple contractors look at it, had multiple hvac companies inspect the furnace and ac units and no obvious issues. One of the hvac companies was convinced that the smell was coming from the crawl space (although the smell doesn’t exist in the crawl space) and being pulled into the supply vents because they are running through crawl space and we’re not sealed well by the builder. The theory was that we had negative pressure in the house because the furnace didn’t have outside air and was therefore pulling in its make up air from the crawlspace. So they sealed all the ducts ( hand sealed the big gaps and aero sealed) replaced some old insulation around the return ducting, ducted out the returns to grills (previously just between floor joists), sealed the furnace better, and added an outside air duct on a timer to bring fresh air into the return ducting.
After all the improvements, the smell is actually worse- the sealing of the ducts appears to be spreading the smell more efficiently. The smell moves around the house and the strength changes by the hour, but is most obvious in two rooms. For the first two months it could only be smelled in the in 2 rooms, but can now be smelled throughout the house. House only smells when hvac furnace/ac or fan are running. The strongest smell is right next to furnace.
The furnace is located in the garage. Through much trial and error, we discovered that if we left the garage doors open to outside all day, the smell reduces substantially even when the equipment is running. We can’t figure out if the smell is getting pulled into the unit from the garage or the garage smells from the furnace.
During two weeks in late summer when we weren’t using ac or heat, the smell went away completely- which leads me to believe this is somehow equipment related (not duct or garage related) but three different hvac companies have “inspected” it but they all seem to do it very quickly- not sure how long it should take someone to thoroughly inspect. The hvac companies don’t think its coming from the unit since they can’t smell it in there when they open it up.
Smell is potent and absorbs into clothing.
Hvac company is coming back to pressure test return system. But after that, is out of ideas.
Questions: what could make that smell? Should we try having a vent cleaner deodorize the vents? Any other ideas? How do we eliminate possibilities/start narrowing in On the root problem?
Thanks in advance
-Sb
Equipment- forced air, 80% efficient gas Lennox furnace with Bryant ac unit, furnace is 5 years old, ac is 4 years old. Furnace is located in garage.
House: 2 story single family (removed from other houses)1990 built house located in the Seattle area. House has floor vents on both floors, a crawl space basement, and unfinished attic (no duct work in attic) and 3 returns, one on downstairs wall (north end of house), one in ceiling (south end of house), and one up stair son floor wall, that appears to actually not be a ducting to anything-looks like builder got away with this one.
What we have done so far: professionally cleaned the vents, had mold air test samplings throughout house (all negative), had crawl space experts inspect the crawl space, had multiple contractors look at it, had multiple hvac companies inspect the furnace and ac units and no obvious issues. One of the hvac companies was convinced that the smell was coming from the crawl space (although the smell doesn’t exist in the crawl space) and being pulled into the supply vents because they are running through crawl space and we’re not sealed well by the builder. The theory was that we had negative pressure in the house because the furnace didn’t have outside air and was therefore pulling in its make up air from the crawlspace. So they sealed all the ducts ( hand sealed the big gaps and aero sealed) replaced some old insulation around the return ducting, ducted out the returns to grills (previously just between floor joists), sealed the furnace better, and added an outside air duct on a timer to bring fresh air into the return ducting.
After all the improvements, the smell is actually worse- the sealing of the ducts appears to be spreading the smell more efficiently. The smell moves around the house and the strength changes by the hour, but is most obvious in two rooms. For the first two months it could only be smelled in the in 2 rooms, but can now be smelled throughout the house. House only smells when hvac furnace/ac or fan are running. The strongest smell is right next to furnace.
The furnace is located in the garage. Through much trial and error, we discovered that if we left the garage doors open to outside all day, the smell reduces substantially even when the equipment is running. We can’t figure out if the smell is getting pulled into the unit from the garage or the garage smells from the furnace.
During two weeks in late summer when we weren’t using ac or heat, the smell went away completely- which leads me to believe this is somehow equipment related (not duct or garage related) but three different hvac companies have “inspected” it but they all seem to do it very quickly- not sure how long it should take someone to thoroughly inspect. The hvac companies don’t think its coming from the unit since they can’t smell it in there when they open it up.
Smell is potent and absorbs into clothing.
Hvac company is coming back to pressure test return system. But after that, is out of ideas.
Questions: what could make that smell? Should we try having a vent cleaner deodorize the vents? Any other ideas? How do we eliminate possibilities/start narrowing in On the root problem?
Thanks in advance
-Sb
source https://hvac-talk.com/vbb/showthread.php?2223263-Musty-cigarette-smell-from-vents-need-help!&goto=newpost
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