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Can not get a sustaining secondary burn

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by ddahlgren, Apr 24, 2013.

  1. ddahlgren

    ddahlgren Feeling the Heat

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    For the last few months I have not been able to get a good secondary burn that was possible before and can not figure out why. They will light off then slowly go down and the fire have too little energy to keep them going. i work my way down to secondaries with a 500+ stove top temp and 650 to 700 flue temp measured with a probe and has been running that way for 10 to 15 minutes. i do not cut the air all at once but in steps about 5 minutes apart and let it stabilize at each step. In general the stove temp goes up and flue goes down. Highest stove temp of 650 with flue probe at 500. the wood re-split oak with a MC of 10 to 14% Packed in fairly tight. At less than secondaries there is plenty of heat but no secondaries at all it just burns with short flames if I am going to keep it going. I am thinking door gasket even though they seem to pass every test is the only way to short circuit the burn. Any ideas at all...???
    Dave

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  2. ddddddden

    ddddddden Minister of Fire

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    From the temps, it kinda sounds like the stove is doing what it's supposed to do. . .

    Maybe the secondary air plumbing is clogged a bit;?
    Baffle out of place;?
    Flue dirty;?
    Defiant likes this.
  3. blades

    blades Minister of Fire

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    Wet Wood? or another way moisture content too high. It is harder to keep secondaries going in warmer temps also as your draft slows down.
    Defiant likes this.
  4. Jon1270

    Jon1270 Minister of Fire

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    Do you see smoke coming from your chimney?
    savageactor7 likes this.
  5. madison

    madison Minister of Fire

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    I think you are exhibiting the signs of woodstoveitus, most commonly observed at the end of the first yr of burning. Joking.

    Walk outside when the stove is not producing the "light show" when you believe it should be and look at the top of your chimney - if there is significant smoke you may have an issue. I would not change the door gasket based on the lack of the "light show" but on a dollar bill test or physical examination of the gasket.

    ///

    It has been my experience, that the "light show"/secondary burn hallucinations can be affected by many factors, including:
    1. Clearing out excess ash inside the stove -- generally a +
    2. Wet wood -
    3. Packing the stove to the gills -
    4. Split size + and -
    5. Species of wood + and -
    6. Draft and outside/inside air temp gradient +
    7. Imbibing in certain substances ++ (joke ?)
    8. Stove design I would assume has some affect
    9. Loading frequency/style
    Defiant likes this.
  6. Jags

    Jags Moderate Moderator Staff Member

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    Warmer weather - less draft.
    Restriction of draft. Pipe or cap dirty?

    Look for smoke. If it ain't smoking, it is probably doing the job. Some wood simply does not off gas as well as others do. Less off gassing, less light show. It doesn't mean that the stove isn't doing its job. The secondaries don't always have to be "rolling".
    Defiant likes this.
  7. oldspark

    oldspark Guest

    Oak will not have the crazy secondaries some woods do so might very well be normal.
  8. begreen

    begreen Mooderator Staff Member

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    I'm going with this direction. If all is clean, it could still be weak draft. What is the total flue height? Describe how the stove is connected and chimney in detail.
  9. ddahlgren

    ddahlgren Feeling the Heat

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    Nothing plugged, no smoke after the first few minutes of light off baffle is just fine wood is dry as mentioned. The draft for such a short chimney is quite good. with air wide open and a warm stove it can pull so hard it looks like it is blowing the fire out. The dollar bill test is something i am not much of a believer in to be honest. You can have high points and gaps that will snag the dollar bill and leak like a screen door.

    My bets are on door gasket but saying that no matter how air gets in it should not let the fire die to nothing. The fire dying out to me means no air to feed it no matter from where so goes against my door gasket thought. Glass is clean 99% of the time unless i do something to make it not clean, like this morning tossing in a wine box that I forgot to put out in the recycle bin and made a couple of soot marks that will no doubt burn off tonight. I waste very little time cleaning the glass as a good hot fire does a fine job of that. I have run the stove fully cleaned out to 3 inches of ash and it just makes no difference. I noticed the biggest difference after having the chimney cleaned and have no explanation of why that might be as I got into a different section of the wood pile at the same time so hard to tell which one made the difference. The chimney was very clean and have not changed burning practices to make it sooty beyond normal. The one odd thing I notice is that it takes a while to get the stove hot and then stays warm for a long time. It is still over 100 after being out for more than 6 hours and was at 500 when it went to coals. Can the fire brick get coated so they do not reflect heat back in or is it just the wood being so dry at 10 or so % MC? I was thinking about taking a wire brush to the bricks to be honest.
  10. begreen

    begreen Mooderator Staff Member

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    Such a short chimney? Seems like you just nailed it. Explain.
    Defiant likes this.
  11. Jags

    Jags Moderate Moderator Staff Member

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    This is telling. It is possible that you are simply burning wood that is off gassing at a slower rate. This would equate to less secondary flame action yet maintaining long heat cycles.
  12. ddahlgren

    ddahlgren Feeling the Heat

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    8 ft indoors and 5 ft of triple wall and drafts very well. Short or not does what it needs to do. Air wide open will turn the stove cold and look like wind is blowing the fire out.
  13. begreen

    begreen Mooderator Staff Member

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    Wide open air should turn the fire into a raging fireball. Something is out of balance. The flue temps are too high which sounds like it is afterburning up in the flue (assuming the flue thermometer is correct). Have you checked the baffle placement carefully to ensure that no flame is bypassing behind the baffle and heading directly up the flue?
  14. ddahlgren

    ddahlgren Feeling the Heat

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    Suspecting the different wood is the whole deal as the stove heats quite well. I am thinking some of the wood so dry the sap is gone and little out gas in the first place.
  15. Backwoods Savage

    Backwoods Savage Minister of Fire

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    ddahlgren, you can also tell a lot simply by looking at that door gasket. If there is a leak, the gasket will discolor.

    As for some of the wood so dry the sap is gone, don't be concerned a bit about that. Evaporating the moisture from the wood is one of the first things that happen! Also, I have yet to see firewood too dry and we typically burn wood that has been split and stacked from 3-7 years.
  16. oldspark

    oldspark Guest

    I dont think so at all, he is using a probe, my flue temps are higher then his with no problems at all and the stove is fine.
  17. begreen

    begreen Mooderator Staff Member

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    BS, you have a cat stove producing heat at the flue exit. His is a non-cat. With a non-cat, normally I like to see the flue temps at or lower than the surface temp once the stove is cruising. Our stove will cruise at 550-600F with a probe temp of 450F usually.
    Defiant likes this.
  18. oldspark

    oldspark Guest

    PE Summit as stated in my posts. My bad you must be talking to BWS.
  19. begreen

    begreen Mooderator Staff Member

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    Yep, I know your stove well.
  20. oldspark

    oldspark Guest

    Ok back to orignal post, my flue temps run high also compared to some but not all.
  21. begreen

    begreen Mooderator Staff Member

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    Sounds like you may have the flue sparky. ==c
    Defiant likes this.
  22. ddahlgren

    ddahlgren Feeling the Heat

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    Looked at the door gasket and it does look a bit iffy in places. I also noticed and never paid attention to before is the latch for the door just closes hard and does not really pull the door in tight before reaching the end of it's travel. the burning season is about over now where I am so will deal with that over the summer.

    I did score a nice load or maple and hickory and have 2 cords of oak that will be be over 2 years CS by this October so 1 more cord of maple and hickory and will be completely out of storage space for next season. What i can not figure out is why maple and hickory is so hard to find with it being such a common tree in the area. The maples grow like weeds around here and every storm some come down. I do know the larger tree service companies do not sell wood they run it all through the chipper no matter how big it is. It sure seems like a waste to me.
  23. madison

    madison Minister of Fire

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    And you later post that the " door handle latch closes hard (?) and does not pull the door tight ...."

    Better start understanding the dollar bill test, and research how to adjust the hinge/latch door fit. Not that it is associated with your original post.

    I would agree that that the short stack is an issue - especially with warmer weather.

    Finally, and not to flame but to educate. Burning trash (wine boxes) could potentially be plugging the cap as well as other issues associated with burning trash in a wood stove.
    begreen likes this.
  24. ddahlgren

    ddahlgren Feeling the Heat

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    Yes understand about the trash and a uncommon thing for me to do. On the latch it closes firmly but you do not feel it compress the gasket any more. There is a ramp in the latch and it goes to the bottom. If it were the draft as I slowly close the ir inlet there will be a point that the amount of air is the same as a day with a stronger draft. There is only one air supply on this stove and no other ports to let air in other than the secondary burn tube. It is either the wood or the firebox in some way just not getting hot enough for some reason. In 2 weeks it will not matter and the stove comes apart for servicing all those things that need doing gaskets, clean chimney, check fire bricks, touch up paint, take a good hard look at secondary air pipeing etc..

    Dave
  25. Backwoods Savage

    Backwoods Savage Minister of Fire

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    BG, with the cat stove, we too have lower flue temps than surface temps for most of the burn. Of course we can't be as exact as you because we do not have a probe but we can tell pretty close.

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