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Heavy puffer sauna stove needs help please

Post in 'Classic Wood Stove Forums (prior to approx. 1993)' started by bandoo, May 15, 2012.

  1. bandoo

    bandoo New Member

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    [​IMG]
    Hi Folks,

    I have sauna stove that we made from a new round boiler body 35" long 20" wide.
    Fed from the outside.

    The vertical pipe is 8" wide. 16 feet high.

    The connector (stove to vertical)is about five and a half feet set at 30%.

    The problem is constant back puffing. Unless the intake is cut to almost nothing (quarter inch or less) it back puffs.

    Even after it's warmed up and the air inlet is closed to about a quarter inch, when I try to increase the fire by opening the draft another less than quarter inch it starts to puff again.

    Opening the door a crack stops it but opening the draft increases it.
    When the door is then closed it puffs unles inlet is closed almost to nothing.

    Outside weather temp is about 75 degrees.
    No outside wind.

    When it's running and the draft is open a tiny bit (quarter inch) it's ok.
    But starting it up is a real process with constant puffing. Then adding wood later or trying to make it hotter in the middle makes it constantly whuff untill it's back to a quarter inch open.

    Round screw in air draft intake is about 3.5".

    Before this I had a handmade square stove box that was about 75% of the size connected to a 6" wide 4 meter vertical pipe and it never back puffed. It had the same five and a half foot connector.

    The galvanized piece covering the pipe as it exits the wall is for safety. (falling pine needles).
    The metal part opposite the damper on the stove is just a stability support and has no other function.

    This is making us crazy trying to figure out what the problem may be.
    Before we changed the verical stove pipe going up it was 6" wide so we figured if we enlarged the pipe to the size on the stove 8" it would take care of the problem, The old upright pipe was 4 meters high.
    The old stove rusted out so we thought of using a new boiler body to avoid the rusting out of the welds on a square stove.

    Maybe the combustion chamber is too big? Inlet too big?Inlet shape?

    I hope I have the images in the right place..The first image is the inside of the stove. The picture didn't get rotated and is on it's side.

    Any suggestions would really be appreciated.

    Thanks in advance,
    micah

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  2. begreen

    begreen Mooderator Staff Member

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    Welcome. Draft sounds like the issue. Changing from 6" to 8" probably didn't help.
  3. bandoo

    bandoo New Member

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    Hi Thanks,
    The stove was made with 8" pipe upright and elbow to start with connected to a 6" connector halfway through the horizontal piece and a 6" 4 yard upright and it was puffing then.
    I thought since it started big that it was getting congested where it joined the 6"er so I did the whole thing in 8". Maybe it should have been 6" from the start?
    Any remedies short of replacing the whole pipe from the top of the stove out?
  4. begreen

    begreen Mooderator Staff Member

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    I would try a 8x6 reducer right at the stove and put the 6" connector back in. Are there any elbows involved here? If so, that's another problem area. If you can post a picture or two that would help. Use the upload file feature.
  5. Jags

    Jags Moderate Moderator Staff Member

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    See here for pics: http://postimage.org/gallery/7i2daz5c/

    Dunno - back puffing is usually from oxygen coming in from the wrong direction (down the pipe). OPENING the air intake is usually the cure. Your stating that you have to CLOSE the intake to make it stop?? But if you crack the door it will also stop? I simply don't get it. That is not the way it is supposed to work.

    By the way - your clearance to combustibles would make me a bit nervous.
  6. bandoo

    bandoo New Member

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    -----------
    Sorry about the false post. I pushed the wrong button......
    ------------
    I know what you mean. This has got me scratching my head.
    I have 4 other woodstoves including a cookstove and have had about 15 different setups from Oregon through Colorado to Vermont over 40+ years and never had a problem with a stove or installation I couldn't solve till now.

    The guy who welded the new stove put a 8" upright welded to the stove to begin with before I saw it. Everything else from the prior stove was 6" iron water pipe that was about at the end of it's life anyway. So After it was puffing away with the 8" going into the 6^' I figured I'd even it out and make it all 8".
    So I'm stuck with this pipe.

    The burn chamber is about the size of a small oil barrel. Maybe it's too big?
    Maybe the air inlet is too big or the wrong shape?
    Or maybe a gremlin.[​IMG]
    Any other sugestions would be appreciated no matter how wild...

    Thanks again,
    Micah
    --------------
    PS:
    I also have a Defiant Encore (junk compared to it's namesake) that when the catalitic converter chamber after 15 years disintegrated, I took a sledge hammer to the inside and removed all the double walls including the one separating the back chamber. Now it holds twice the wood and has been fine for 10 years. Also got a Hartland cookstove and a few small Yotols and Waterfords here and there.
    I have been running a sauna stove in this same spot for about 15 years and have checked out the combustibles within range of the stove, The walls around the stove are cement blocks and anywhere else has suspended metal sheets or is not near enough.
    There is a little wood house we built above it so we are really really sensitive to the issue of fire.
    Both the Hartland and the Defiant have double wall 8" pipes...
  7. begreen

    begreen Mooderator Staff Member

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    It looks like the smoke has to make 2 90 deg turns. Add a long horiz. run, oversized pipe and warm weather and I can see why draft is reversing. Is the horiz. run dead level or is it pitched upward toward the chimney cap?
  8. bandoo

    bandoo New Member

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    No it's not level at all. The angles at the joints are 30%..
    The smaller stove before it in the same place with the 6" pipe was dead level and never smoked....
    thanks.
  9. begreen

    begreen Mooderator Staff Member

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    Well, that's good. I'm curious why the smoke outlet was place far below the top of the stove? That would seem to be an issue too.
  10. bandoo

    bandoo New Member

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    You mean on the inside of the stove?
    I think it was a way for the welder to be sure he got a good weld job. Sometimes that's the place where they rust out first.
    I was wondering the same thing too.
    Is that what you were referring to?
  11. begreen

    begreen Mooderator Staff Member

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    Hard to tell from the pictures but it appears to exit several inches from the top of the stove. What is that dimension?
  12. fossil

    fossil Accidental Moderator Staff Member

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    I dunno either, but having read all through the thread and looked at the pics and thought about what everyone has said, it seems to me that the most significant thing about this system that's different from the previously trouble-free systems is the stove design/configuration itself. The positioning of the outlet flue collar on the end of the stove seems a whole lot less than ideal to me. Rick

    ETA: I may well be seeing something in the pictures that differs from reality...it wouldn't be the first time. Even if I wasn't looking at a picture. :p
  13. bandoo

    bandoo New Member

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    From the top. 20"high by 8" wide.
  14. bandoo

    bandoo New Member

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    I didn't like the look of that piece myself.
    The maker had already done it and had installed the damper so I reluctantly went along with it.
    It seemed it could be supercharging the air and somehow causing a combustion problem.
    The last stove in that place had a maybe 6" piece before going into a 45% angle piece for about a foot and a half before it hit the long horizontal.
    Could that be it? Could the whole thing being 8" also mess it up somehow?
  15. bandoo

    bandoo New Member

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    I agree.
    Are you talking about the position or configuration?
  16. fossil

    fossil Accidental Moderator Staff Member

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    I don't know what I'm talking about...I'm revisiting the pics and trying to figure out just exactly what I'm looking at. Rick
  17. bandoo

    bandoo New Member

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    If you need any info or other pics please ask.
    Thanks a lot.

    I really appreciate the help.
  18. Jags

    Jags Moderate Moderator Staff Member

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    What is the relationship between the top of the loading door and the bottom of the exhaust? If the loading door has any portion of it higher than the bottom of the pipe the stove can literally be confused as to which one is the exhaust. Also, if they are in close relationship it will adversely effect the draft, creating a low or lazy draft.
  19. bandoo

    bandoo New Member

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    I'm not sure exactly what you mean though.
    When we first made the door it was too low to add wood comfortably so we cut it higher. But that was after the backpuffing started. It backpuffs when the door is closed.We just redid the door.
    Is that what you were asking?
  20. Jags

    Jags Moderate Moderator Staff Member

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    I am basically asking: how much higher is the exhaust stack from the top of the door and also the top of your primary air inlet? The exhaust needs to be significantly higher than the air intake. Its the whole "hot air rises" thing. Also, is this a sealed (gasketed) stove?
  21. begreen

    begreen Mooderator Staff Member

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    Moved to the non-epa stove forum.
  22. bandoo

    bandoo New Member

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    It's 12 inches from the center of the primary air inlet to the bottom of the exhaust pipe.
    The top of the door is level with the exhaust.
    We just redid the door to make it easier to load. Before it was lower but there was no change with the puffing with the new door shape.
    It's pretty close to airtight I would say. The door is not gasketed but pretty tight.
    When the stove is hot and running and the inlet is open a half inch there is no puffing. Open it another half inch and it gets puffing.
    Could it maybe the upright piece off the top of the stove?
    Maybe it should come out a few inches then go into angle before exiting the wall?
  23. Jags

    Jags Moderate Moderator Staff Member

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    Dunno - possibly. When you refer to this "back puff" is it like little mini explosions? Or is it puffs of smoke? Something else? I just want to make sure we are talking about the same thing.
  24. bandoo

    bandoo New Member

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    It's small puffs of smoke chugging out like about every half second.
    I didn't see fire coming out..
  25. Jags

    Jags Moderate Moderator Staff Member

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    As a test, when this thing starts puffing like the little engine that could, take a piece of tin (or something non combustible and cover about half of the exhaust stack (at the top). See if that stops the puffing. I am suspecting very low stack temps. Do you ever sweep the stack? Do you get much black or gooey stuff in the stack?

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