A smell when the furnace kicks on

We have a gas furnace in our house and recently I have been noticing a skunk smell or some sort of sewage type smell whenever the gas furnace unit has kicked on and started running.

And this is not really a decaying type of smell like a dead animal, either.

It’s mostly just a skunky kind of smell. We already have a carbon monoxide and gas detector so it’s not really a problem with that. Our house is built on a cement foundation, and so there isn’t any basement. The air ducts are all under the floors, though, and the actual gas furnace is in a bedroom closet downstairs. I was starting to wonder if maybe there was a skunk in the air ducts under our floors or something, and so I asked a friend of mine who is an HVAC technician if he had ever heard of that. He actually said that my carbon monoxide detector would not be able to detect natural gases if there were a gas leak in the house but that my gas company would be able to come and check it out for me for free. Then he said that it could possibly be a sewer gas problem from a broken trap. He said that if the trap is messed up on the condensate pipe on the air conditioning, then it would smell. The pipe goes to the drain and the drain sometimes smells and goes up into the pipe and then into the air ducts. That explanation made a lot of sense to me so I’m going to call both a plumber and an HVAC technician today. I have got to get rid of this smell!


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