AS Reburn puffing?

Discussion in 'Modern EPA Stoves and Fireplaces' started by Marshel54, Mar 25, 2020 at 5:18 PM.

  1. Marshel54

    Marshel54

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    My AS has some fairly violent puffings from the reburn igniting. After the puff reburn goes out until the next time gasses build up. Which way to move the incoming air?
    I have given it more air and had a nice established reburn. I have also reduced the intake and got the same results. What is the key? Does not appear to be any rhyme nor reason.
     
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  2. Nitrodave

    Nitrodave

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    In fire service terms... you are experiencing “Backdraft” ... (Remember the movie ?)

    a backdraft occurs when there is a high heat, high fuel gas (smoke), but lacks oxygen, then gets a proper amount of oxygen... then POOF !!

    It’s happening in our stoves, because they close down so much. The smoke builds up, chimney cools and firebox goes rich. It then cools off enough that There is less fuel gas and it leans out .... poof !! Then the cycle continues. So you either need to cool the coal bed... shut air down ... or the quicker way is to open the rear air and let it flush some of the fuel through. Don’t open the door when the box is black... you will have a bunch of smoke in the house !! I have found that this only happens about an hour after a good reload. Just try to keep a small lazy flame, then it won’t happen.
     
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  3. BDF

    BDF

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    Often opening the draft slightly will cure back- puffing. Sometimes, closing it will also. The problem is that there are so many variables, no one can say anything so simple as close the draft 10% and all will be well.

    The cause, as you already pointed out, is the collection of flammable gasses and introducing just enough oxygen (from the air) to ignite those gasses. The 'cure' is to prevent either the flammable gasses from collecting so much, reducing the available oxygen in the firebox or both. Back puffing is often a problem with very dry wood such as kiln dried lumber. Being pine, it also off- gasses at a very high rate as compared with hardwoods. Another problem is getting the entire firebox full of wood up to temperature so that it pyrolyses (smokes) and then shutting the draft way down for the long burn. Instead, try starting off with a much smaller amount of wood, get it well- engaged, then load the stove and shut the draft down without allowing the entire load of fresh fuel to get hot enough to generate smoke. Thing of it like the way a cigarette burns: from one end and it just smolders. But if the entire cigarette is ignited, it will make a huge amount of smoke all at once.

    Finally, mixing in a little [less dry] wood can help immensely. We all strive to burn dry wood, and we should but extremely dry wood can also be problematic.

    Brian

     
  4. TurboDiesel

    TurboDiesel

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    More often than not, i open the draft and get a little more flame to stop the backpuffing.
    It usually doesn't backpuff unless it's a little warmer outside and or rainy
     
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  5. Marshel54

    Marshel54

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    Exactly what I was thinking, but the other night reducing air solved the problem.

    Exactly what I am experiencing.
    Was definitely not to dry of wood. I was burning black locus that was css last winter. Most of the time the firebox is full when I experience it the most. When I can get it throttle down with a lazy dancing reburn it put out a tremendous amount of heat.
    How is Phoebe doing?
    The last couple of times it has been fairly warm and rainy. I often times delay bedtime until I am comfortable not having backpuffing.
     
  6. Nitrodave

    Nitrodave

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    that’s because reducing the air , cools the fire, which in turn produces less fuel gasses.. which leans the firebox and no more poofing.
     
  7. brenndatomu

    brenndatomu

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    This ^ ^ ^ just the way the Kuuma furnace burns too...starts in the front and keeps the front of the splits burning juuust enough to off gas...but since you guys have a cat, the AS can burn lower and slower than the non cat Kuuma can.
    Loading on some hot coals at the front makes the whole process work better too...not sure if that would apply to the AS or not?
     
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  8. Nitrodave

    Nitrodave

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    One possible drawback to the AS, it side loads, so it East west... but the air curtain come down the front glass and hits the side of the splits... hard to get that end burn type fire..
     
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  9. BDF

    BDF

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    OFF TOPIC:

    Phoebe is doing great! A big cat in the first place, she is also pretty fat- I call her 'Jabba the cat'. But she seems perfectly content, is a great pet and is actually getting quite affectionate, more than two years since she 'moved in'. :)

    Brian

     
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