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White sky - smoke! Failing cat?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Joful, Jan 14, 2013.

  1. clemsonfor

    clemsonfor Minister of Fire

    Joined:
    Dec 15, 2011
    Messages:
    2,394
    Loc:
    Greenwood county, SC
    Just finished loading, took maybe 5 mins with a few trips and finding the right pieces, several trips to the shed, door cracked while waiting. OK I closed bypass at 10:41pm. When I put it into bypass it was 740F(CAT probe temps, which is what all the temps I give are), 2 mins later it was at 800F. Some stuff is oak that was split this summer but from dead tree ( I know its no where near 20% but it was on top and split right size. The rest is elm that was cut/split this last spring so it should be close, also some cherry that is at 20% guessing from same time, and some 2yr oak css on bottom, so its not the best load but its not suppose to be super cold so I am kind of mixing what I have tonight burn. Just looked its 10:48pm and I am reading 980F. and I have cut my air back at this point to about 2/3 open, so I have closed it by 1/3. Its 10:50pm and I have a reading of 1090F. 10:55Pm and reading 1210F. 10:57 and its showing 1290F. At about 10:55 I see the secondaries at the top starting to kick of. There pretty constant and blue just burning at the top right now, not really dramatic, but with some of the wood I put in there im not really expecting the northern lights. And its 10:59 and about 13:05. I have had enough of sitting here watching this and I am going to get into bed. This is also with the blower on low, if I have it on high I am confident that this will not raise as fast. But I just turned it down to low as I loaded it cause it was blowing burning hot air in my face as I reloaded, some air from the sir around stove but more so it was blowing the hot @$$ air that was in the stove flooding out of the door at me!!!

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  2. clemsonfor

    clemsonfor Minister of Fire

    Joined:
    Dec 15, 2011
    Messages:
    2,394
    Loc:
    Greenwood county, SC
    just went and peeked. I turned blower up to say 80-90% of its full speed (rheostat) and it was right about 11:17 and the temp was right a shade above 1300F and there was yellow secondaries constantly hugging the ceiling, no flames on the wood but just puffing like a cigarette. Air was cut back to about 25% before I went to bed the first time. Did not mess with any setting just went back to room.

    I also forgot that I had a piece of ash in there that was css the same time as the cherry and elm.
  3. WoodpileOCD

    WoodpileOCD Minister of Fire

    Joined:
    Jan 19, 2011
    Messages:
    659
    Loc:
    Central NC
    I think you misunderstood. It takes about 45min to go from a cold start to 1000, not 400 to 1000.


    I agree with jharkin. I think your cats are fine. I think as long as you can get them to cruise between 1000 and 1500 they are working fine. I'm in my third year with mine and I have no idea how long they were in there before I got the stove or how they were treated.
  4. jharkin

    jharkin Minister of Fire

    Joined:
    Oct 21, 2009
    Messages:
    3,238
    Loc:
    Holliston, MA USA
    Ahh 45 from cold makes more sense, thanks.

    BTW I think adjusting my secondary thermostat may have helped. Have to watch it and see.
  5. Diabel

    Diabel Minister of Fire

    Joined:
    Jan 11, 2008
    Messages:
    865
    Loc:
    Ottawa, ON
    Jeremy
    How do you adjust the secondary air and why?
    Thanks
  6. WoodpileOCD

    WoodpileOCD Minister of Fire

    Joined:
    Jan 19, 2011
    Messages:
    659
    Loc:
    Central NC
    What kind of sec. thermostat do you have and how does it work?
  7. jharkin

    jharkin Minister of Fire

    Joined:
    Oct 21, 2009
    Messages:
    3,238
    Loc:
    Holliston, MA USA
    Vermont castings catalytic stoves have four air inlets and two thermostats. Both are bimetallic coils.

    The primary thermostat is attached to the main air control level and regulates the primary air, similar in concept to Blaze king, though its generally accepted around here that Blaze King's works better.

    The second thermostat is fixed (but adjustable cold) and controls secondary air feed to the catalyst. I had to search a bit, but found this old thread with a picture:

    http://www.hearth.com/talk/threads/...ndary-air-intake-question-with-picture.27345/

    Basically there is a bimetallic probe in the cat exhaust that controls the opening of a secondary air door. This are feed passes around the refractory box to preheat and feeds directly into the cat hood intake. The idea is that the thermostat feeds extra air when cold to aid light off and then closes as the cat heats up to prevent over firing. You can see in the picture there is a screw in the center of the coil allowing you to set how open the door is when cold.

    It been theorized that if its not set right, in addition to making light off harder, when the cat is really hot the coil can turn past the 180 degree full closed position and actually reopened the door again - this might be what happens when one of these stoves goes into catalyst runaway.

    The factory setting is supposed to be "between 4 and 5 o'clock" for the end of the coil. I looked at mine and it was closer to 5, leaving the door only 1/8" open at cold. I opened it closer to 4 o'clock to se if it will improve things. I do think I got a faster light off and did not see and difference in cruising temp so far.


    (BTW the third and fourth air I mentioned above are the two small holes behind the legs that feed air into the coal bed from the ashpan, this is to satisfy the EPA minimum primary air requirement I believe and helps to keep the coal bed hot)

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