fireplace smell when AC runs

Last fall we had the flue replaced in our fireplace. It was the type that sits right over the fire. It was rusted out. We replaced it with a flue at the top of the chimney. The cord runs down the chimney, and you close it by pulling the cord down and hooking it off to the side. This worked great all winter.

Only we turned the air conditioner on for the first time this spring and we smell--in the room where the fireplace is--a faint scent of the chimney. It is not unpleasant, sort of like the distant scent of a campfire. Anyone have any idea why this would be happening? Is it an indication of a problem?

Thanks in advance!

I'm assuming that you mean flue damper. It seems to me that you've got a little negative pressure in the house when you're running the AC that's sucking some air down the chimney and with it the smell. A chimney cleaning generally helps with creasote smells. Is your house really air tight? You might need to make it less so.

I would check for proper combustion air supply, and then investigate the return air and curculation of heated air. Try different combinations of opening and closing interior doors, and see if that makes any difference.

prescottrecorder said:

I'm assuming that you mean flue damper. It seems to me that you've got a little negative pressure in the house when you're running the AC that's sucking some air down the chimney and with it the smell. A chimney cleaning generally helps with creasote smells. Is your house really air tight? You might need to make it less so.

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The house is a 1-story brick ranch built in 1961. I do not think it is completely air tight. I cleaned out the fireplace ash and a log left over in there after the winter, and then, after running the AC for another day, the smell has subsided. Not sure what to make of it.