1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)

Air flow paths and reburn chamber

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by wahoowad, Jan 9, 2006.

Thread Status:
Not open for further replies.
  1. wahoowad

    wahoowad Minister of Fire

    Joined:
    Dec 19, 2005
    Messages:
    1,544
    Loc:
    Virginia
    I'm confused how any unburned gases enter the reburn chamber at the top of my Jotul 3CB firebox.

    I have two air inlets/controls at the front of the unit that appear to provide combustion air into the front of the firebox. I observe the flames and they seem to flow up to the ceiling (which is actually the floor of the reburn chamber), then forward to slip past the gap at the top of the firebox and into the top part where the exhaust vent is located. The reburn chamber has a bunch of holes in the leading edges as if gases or exhaust flows though them somehow, but I do not understand how any of my unburnt gases actually get into this area to be reburnt?!?!

    Helpful Sponsor Ads!





  2. wg_bent

    wg_bent Minister of Fire

    Joined:
    Nov 19, 2005
    Messages:
    2,248
    Loc:
    Poughkeepsie, NY
    I think those holes just allow super heated air to enter whereby the hot air ignites the unburned "gases"
  3. wahoowad

    wahoowad Minister of Fire

    Joined:
    Dec 19, 2005
    Messages:
    1,544
    Loc:
    Virginia
    Warren,

    I could follow that if maybe the air entered that chamber from behind and flowed through it, but why would air bother entering a confined space when it has a free exhaust path up and out?
  4. wg_bent

    wg_bent Minister of Fire

    Joined:
    Nov 19, 2005
    Messages:
    2,248
    Loc:
    Poughkeepsie, NY
    The design of your stove plus the chimney pulls air into the stove's primary air, the air is divided so that it gets pulled through the air wash system. How they manage to do that in your stove is the element of the design engineering that I'd have to see to understand, but all non-cat EPA stoves do this.

    I remember Elk responding to a post where the person wanted to design their own stove because they were good with a welder...Elk's point on his response was that it's really hard to design a good stove, and many have failed with big budgets and R&D staffs. Airflow is the magic in an EPA stove.
  5. Mike Wilson

    Mike Wilson New Member

    Joined:
    Nov 19, 2005
    Messages:
    1,003
    Loc:
    Orient Point, NY
    I think "reburn chamber" is a slight misnomer. The holes you see are not porting gasses from the fire, they simply shoot hot air into the top of your firebox. The unburned smoke from the fire below it comes up, hits the new source of (hot) oxygen, and ignites, thus "reburning." You'll see what looks like flames from a gas cooking stove coming from these air ports. From there the flame will curve up and around your air baffle plate, and exhaust up the flue. No "burning" goes on behind (above) the baffle plate itself. Note, the baffle plate is suspended and separated from the top of the stove, so that the stove body itself does not act as a heat sink and cool the plate down (you want hot air coming out of the jets). Some stoves have insulation up there, I don't believe yours does.

    -- Mike
  6. adrpga498

    adrpga498 Minister of Fire

    Joined:
    Nov 18, 2005
    Messages:
    866
    Loc:
    New Jersey
    Mike I have the catine and your exactly right. The burn isn't inside the baffle as one may suspect. If the fire isn't too high not all levels (3 on mine) will show air movement.
  7. wahoowad

    wahoowad Minister of Fire

    Joined:
    Dec 19, 2005
    Messages:
    1,544
    Loc:
    Virginia
    So let me see if I get this right. The reburn chamber (2 rows of horizontal holes) is not fed with any combustion air from outside my stove and has no appreciable air flow through it. Gas reburn occurs when unburnt gases flow up and past the holes and somehow superheated air from inside the chamber ignite them. The reburn happens outside the chamber, not in it.

    I guess I thought the reburn occurred inside the chamber given how I see jets of fire seemingly shooting out. Somehow I suspect there is still a circulation of air (perhaps coming in from the upper row of holes?) given how the jet of combusting gases must stimulate air movement from within the chamber.

    Today was my longest burn and I have observed it a lot through the glass door. Also watching how the stovetop temps vary based on the type of combustion going on.
Thread Status:
Not open for further replies.

Share This Page