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Community and Q&A

Masonry fireplace smoking tight house

mtndrew | Posted in GBA Pro Help on

I built a tight house with fresh air HVAC intake and managed exhaust with bath fan timers. My clients insisted on a masonry fireplace and once put to use, indicated having to open windows to keep smoke from infiltrating the house. I ended up installing a 4″ cast-iron fresh-air intake vent through the back wall of the firebox and clients still have to open window(s) for enough outside air CFM. Should I install a larger floor vent in front of the hearth to allow for this additional air need? Is there another solution to keep my clients from having to open windows?

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  1. Expert Member
    Michael Maines | | #1

    Mtndrew, that is a common issue when burning wood in a reasonably tight house. The fireplace should draw better once the chimney is hot, but an open fireplace really has no place in a modern home, aesthetics aside. Providing additional makeup air might help, but you should really talk them into adding doors to the fireplace, or better, installing an insert.

  2. MattJF | | #2

    A fireplace insert with a fresh air supply is going to be the best option.

    Open fireplaces should probably not be allowed in current code built houses.

    Have they tried running the furnace fan, which should pressurize the house?

    A makeup air fan may be needed. Ironically the makeup air may cause comfort issues and need an inline heater.

  3. Nola_Sweats | | #3

    I had a smoke-infiltration problem for years with my wood-burning fireplace. I eventually realized that all of the smoke was coming in within the first few minutes, before the draft got going. It was a simple matter to light the natural gas igniter for a few minutes until I could see there was a draft, then add wood after that. I can't imagine a 4" supply wouldn't supply enough air unless they're burning a huge fire.

    Also, natural-wood fires are aesthetically lovely. I know they're terrible energy-wise, but I like them ... assuming you've got an ample supply of firewood and don't live in an area with air quality problems. I've since moved to a more urban area, into a house with a gas fireplace that we never use because it's boring and, worse, it's not vented to the outside. Life was a little better with a real fireplace. YMMV.

    1. MattJF | | #4

      Whoa, I didn't even know a natural gas wood fireplace starter was a thing.

      Growing up we always started the wood stove with a propane torch. Before lighting, we would always put the torch in what I guess was a clean out door for five minutes to get a draft going prior to lighting.

      1. Nola_Sweats | | #5

        Yeah, it was very convenient and more reliable than starting with paper or kindling. A "Dante valve" or a "Dante kit" is what it was called. It would also work with gas-only ceramic logs, although not as nice-looking as a gas kit expressly designed for ceramic logs.

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