Quill Posted By Quill, Mar 22, 2006 at 8:33 PM

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  1. Quill

    New Member 2.

    Mar 22, 2006
    I have a fireplace built in the early 50s with a metal firebox that was designed to let heat passively circulate around it and rise out of vents above the mantel. That feature works well, but the problem is one of turbulence... there is always a pronounced rolling cylinder of smoke coming up from the back of the firebox. This isn't a problem with the doors shut, but if I open them to fiddle with the fire or add a log, smoke swirls out into the room. Big time. With one side door open it turns into a mini-cyclone, spinning very fast. It doesn't seem to be a problem with draw, unless perhaps it is drawing TOO well (it will pull the doors shut with some force). The chimney is on an internal wall and appears to have an 8x8 flue (the chimney vents a small furnace as well, but the problem persists even if the furnace is shut off). The damper is at the front of the firebox and has a opening of 28x4. With the doors open the front opening is 28x18. The only thing that appears missized is that where the metal of the firebox above the damper tapers down to about a 6x6 opening, the mason put 2 courses of brick that narrow further to perhaps 4.5x4.5 before opening to the chimney proper.

    If I partly close the damper it seems to help a little.

    I'm guessing that the narrow section is at fault, that the turbulence comes from the increased speed thru that section.

    My questions are-

    What else could be going on?

    Might it help to add a baffle?

    Would I have the same problem if I stuck in an insert or perhaps a small wood stove?

    tia- quill
  2. MountainStoveGuy

    Minister of Fire 2.

    Jan 23, 2006
    Boulder County
    I would say you have a draft issue due to one of many things, chimney hight, plugged cap, negative pressure do to exaust fans or a very tight house.
  3. begreen

    Mooderator 2.
    Staff Member

    Nov 18, 2005
    South Puget Sound, WA
    Are you saying that there is a furnace on the same flue as the fireplace? That I believe is a real no-no.
  4. elkimmeg

    Guest 2.

    In the 50's there were no codes. First time I heard of an 8/8 used for a fire place reduced to 4.5 to 4.5? connected to another applaince? and you wonder what why it is not opperating properly? Even your post indicated The flue alone without being connected to your burner can never handle the opening size of the fireplace.
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