I am having a backdraft condition on a new brick one story chimney, We built a new 20’x25′ family room onto a 50’s vintage center hall colonial. The fireplace burns great, but when there is no fire the entire house smells like smoke even when the damper is closed. The addition of glass doors and an additional flue top damper has not helped. When plastic is taped over the glass doors it billows into the room like a sail, when a window is cracked open it goes slack. Is there some way to equalize pressure in the house to get rid of the smoke smell? I have thought of a fresh air vent to the fire box but am afraid it will only make the smell worse. I am trying to avoid adding 12′ to the chimney because I think it will look silly. Thank you Gilhoran
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The code in Chicago is 3' over 10' for residential fireplace chimney's. It has got to be close to that for you. You need that for 2 reasons. 1.fire safety, burning ash or sparks are already above the roof line when exiting the flue. 2. smoke draw from the firebox to avoid back flow. Check what your local code is first before you knock going higher. Form does follow function.
something in your house is requiring makeup air and is tking it from the chimney.
it could be a combination of all the other fuel burners and vents or it could be just one - or a window left open or a whole house fan or......
On the chimney height, it should be three feet above the ridge or two feet above and roof point within ten feet of it.
Draw is also effected by the ratio of height, flue size vs firebox openning. Too laarge a flue for the box ould contribute to this problem
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...What Piffin said. Consider bathroom fans, range hoods, even clothes dryers. Anything that creates a negative pressure inside the house will draw from the path of least resistance. A wide open chimney is pretty "least resistance".
If your house has a makeup air source, check to be sure that it isn't somehow blocked.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
You might go to http://www.woodheat.org and read their expert info on chimney placement and design. Your problem sounds like what they describe as "Cold Hearth" syndrome. When there is no fire the cold low pressure zone around your fireplace is drawing outside air down the chimney. This effect is created by the warmer high pressure air escaping in the upper living areas of you house. In their words, "your house is a better chimney than your fireplace chimney".