Ask Your Question

Angie's List Answers is the trusted spot to ask home improvement and health questions and get answers from service companies, health providers and consumers. For ratings and reviews on companies in your area, search Angie's List.

Top 30 Days Experts
Rank Leader Points*
1 kstreett 240
2 Guest_9020487 110
3 Guest_9190926 105
4 GoldenKid 100
5 ahowell 95
6 KnowledgeBase 95
7 skbloom 80
8 Guest_98024861 70
9 Guest_9311297 70
10 Guest_9400529 70

*Updates every 4 hours

Browse Projects By Category

Question DetailsAsked on 11/19/2015

Acrid smell on main floor room over mechanical room only...not present in summer, only winter

Not really evident unless door to room is closed...then very strong smell develops pretty quick...uplift pump and gas dryer, furnace water heater in mechanical room..odd thing is that the mechanical room doesn't smell

Do you have the same question? Follow this Question

3 Answers


Sounds pretty straight forward to me (though that might be deceptive) - happens when you cut off fresh air flow (at least partly) to the mechanical room when the furnace is running (or maybe only when the dryer is running, or maybe some combination). Sounds to me like your heating appliances may be starving for air, so they are pulling a partial vacuum on the house to get combustion air, or your ducts are leaking enough that the return air is signficantly less than outgoing so again the furnace is pulling makeup air from the house. This could be pulling flue gases from the exhaust flue through cracks or open joints, or could be pulling sewer gases from a trap somewhere in the area. Or since you said an "uplift pump" which I infer to mean a sewage lift pump, perhaps it has an air vent that is staying open, so when the furnace puts a slight vacuum on the house getting combustion and makeup air, it is pulling sewer gases into the house fro the sewer pipe.

Another possibility is an undersized or partly blocked exhaust flue that is leaking into the main room area when the furnace fires - or maybe only when the furnace and water heater are firing together, for instance.

Actually - unless this is a pretty big room, having the gas dryer in there might be illegal anyway unless the door is essentially all louvers, because it pulls a lot of airflow in use, which can backdraft the gas heaters.

First thing I would look for is if the ventilation grillage or louvers in the door have been closed off (or door replaced with solid one), or fresh air inlet vent in wall has been plugged off (this is VERY common - homeowners and contractors alike run amok with spray foam filling required fresh air intakes into utility areas).

Also, check all drain traps that are not commonly used (unused washer drain, floor drains, unused guest or basement bathroom drains, etc) are all full of water so sewer gases can't get inot the house.

I would say you need to get a Heating and A/C contraxtor - and explain the situation and that someone suggested it might be a makeup air deficiency situation, so you want him to bring the necessary device to measure pressures in the equipment room, furnace, and flue and ducts.

Of course, if he finds that you are pulling too much vacuum on the house, he can remedy that with makeup air inlet, but you may still have to trace down the source if it is a sewer pipe leaking gases in to the house - which a Pllumber would be the vendor for.

Answered 4 years ago by LCD


Thanks for responding! You gave a lot of great insight and advice which we will follow up on. Also, I realize that I might have not been clear about where the smell is. The mechanical room doesn't smell, the smell is only in the room that is above the mechanical/laundry room, and we keep the door to the laundry/mechanical room open, so the air source for the furnace etc. is not only from outside, but also from the basement. There is a bathroom that isn't used much in the room that adjoins the mechanical room.. I will flush the toilet often, to see if that helps.

Answered 4 years ago by Burlington


Ok on the ventilation access - though depending on how large the surrounding room is, might still be short on makeup air if there is not outside ventilation provided - commonly through a screened but otherwise open 6-12 inch range duct through the wall to outside air.

Could still be a furnace exhaust duct leak into the room above, if the flue passes through a wall adjacent to that room - especially if oil fired furnace, their exhaust can be pretty rank.

Certainly check out ALL drains (sink, toilet, tub/shower, any floor drains or unused washer drains) - put some lemon scented dish soap or such in hot water and pour about 1/2-1 gallon down each drain that is not frequently used - then remember to add a quart or so of water to those drains every several months (can require every month or two in very dry climates - or adding an anti-evaporation fluid available at your plumbing supply, which floats on the top and essentially stops evaporation). Might or might not be actual sewewr gas leakage from the traps - could be they are going stagnant and during the heating season the stagnant smell is migrating from the drains into the room.

If that makes no difference, then probably back to the Heating and A/C contractor to check your heating airflow and inspect the flue for holes or loose joints.

Answered 4 years ago by LCD

Related Questions

Terms Of Use
Privacy Policy