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We have a wood-burning fireplace in our family room. Fifteen feet from the fireplace is a large cold air return. When the fireplace is stoked, nice and cozy, everything is fantastic. When I shut it down for the night, I close the flue, shut the glass doors, and go to bed. The problem...

Throughout the night the cold air return seems to be pulling the smell from the fireplace into the system, circulating it throughout our home. Getting rid of that smokey smell is tedious and makes burning the fireplace quite unappealing.

It's possible I have the problem wrong but I do recognize the symptoms. I would love to be using my fireplace but really don't want my house smelling of smoke all the time.

I would appreciate thoughts on how I might be able to resolve this issue. Would a fireplace insert help? How about blocking the cold air return (seems like a bad idea)? Should I leave the flue open?

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2 Answers 2

When I light my fireplace I leave my flue open for the night. The residual smoke from your fire is putting the smoke smell in the house when you close the flue

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Good call Sam. The flue should not be closed until all combustibles are totally extinguished. –  shirlock homes Dec 16 '12 at 10:27
    
OK. So assuming the flue stays open to clear combustibles and smell, I wonder (aloud) if closing the glass doors and leaving the tiny vents open are enough to allow the circulation for air to rise out the chimney. What is going to move that air up and out once it's cooled? –  allnightgrocery Dec 16 '12 at 14:25
    
@allnight: good follow up question. Not sure just how tiny these vents are, it doesn't really take much to provide enough combustion air to continue burning off the remaining coals. I'd say if the doors are meant to be closed during use, you're OK. If they must be open, you may want to at least leave the doors ajar. Once things have cooled, nothing will move air up the flue, there's the rub. If combustion slows enough and the flue cools enough, smoke will still back up into the room. Best to break up and arrange the remaining coals to burn completely before things cool too much. –  bcworkz Dec 16 '12 at 21:11
    
@bcworkz. The cover for my fireplace has two glass doors, designed to be closed, with a grill at the bottom with vent holes that can be closed as well. I have no issue closing the flue but getting a good evacuation is apparently the key to removing the smoke smell. How can I do that? Is it truly a crap shoot with the proper extinguishing of expiring coals? –  allnightgrocery Dec 17 '12 at 19:46

As mentioned by Sam, you must leave the flue damper open until the wood has completed burning or is fully extinguished. This is really an answer to your follow up question. I tried to address it briefly in comments, but ran out of allowed characters. I also hate multiple run on comments and the inability to break my comment into paragraphs, so I'm making this an answer.

Not only must you leave the flue damper open, but you must maintain an adequate combustion rate so the established draft up the flue continues to evacuate smoke as long as the wood is burning. The problem can and will arise where the combustion slows so much that the flue cools and the draft is blocked by cold air. Now smoke will have no where to go but back into the house.

The best way to prevent smoke in the house is to have the fireplace ducted to use outside combustion air. This way, the combustion chamber is sealed from the house and only very small amounts of smoke can leak through the joints in the doors.

Outside combustion air is not always a viable option. The next best option is to configure the combustion air openings and arrange the remaining coals to burn as rapidly as possible before retiring for the night. Thus the flue will stay hot until the wood is fully consumed.

A reasonable start point is to break up the remaining large chunks of coals and arrange them in a pile directly below the front edge of the smoke shelf. If chunks of wood are not burnt enough to break up, place them in the center of the pile and push smaller pieces up against the big ones. Your ability to do this will be limited by grate or andiron configuration. You don't need to go through extraordinary measures, just do the best you can. Close the glass doors and leave the combustion air vents wide open.

If you still get smoke backing up, experiment with leaving the doors ajar. You will provide more combustion air for faster burning, but also allow a free path for smoke to enter the house. If you restrict the combustion air further, you restrict the ability for smoke to enter, but you increase the chance of the flue cooling before the burn is complete. It's sort of a Catch 22, but hopefully you'll find the optimal arrangement.

An alternative approach if you plan on rekindling the fire in the morning is to re-stoke the fire a bit before retiring. Once the wood is fully charred and embers are forming on the edges, close the doors and restrict the combustion air intake enough to really slow combustion, but not so much that the fire chokes itself out and you're left with a bunch of cold charcoal and a strong creosote smell. The idea being by morning there's still embers burning and the draft is still established. Restarting the fire should be very easy. It will take some experimentation to determine the right combustion air volume. It varies by fuel load, log size, wood type, moisture content, outdoor air temperature, etc.

Another trick is to not fully clean out the ash all the time. The embers burn hotter on a thick bed of ash than they will on raw fire brick or a thin ash layer. This will help keep the draft established.

Accidental smoke entry seems to be inevitable with wood burning. But it should be just that, an accident, not a regular occurrence. It may take a little trial and error, but you should find a way to operate your fireplace so that you can enjoy it without much concern for smoke odors in the house.

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The outside air source would that be a small vent on the outside of the masonry base of the fireplace? –  Mike yesterday

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