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The secondary burn at lowest setting

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by wg_bent, Dec 15, 2005.

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  1. wg_bent

    wg_bent Minister of Fire

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    In my Osburn, about 10 - 20 minutes after adding several logs, the secondary burn flame seems to be pretty much filling the entire firebox, even with the draft control at it's lowest setting. Lots of heat coming out of the stove, and at times the rearmost burn tube can have a slight glow to it. I do get concerned about over firing. I know the new EPA rated stoves aren't designed to smoulder like older stoves, is this just the way they all are? Seems like after the wood has burned for 20 minutes or so things settle down a bit, but it sure gets hot for a while. Typical?

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  2. Rhone

    Rhone Minister of Fire

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    I vote that's normal. Your secondary burn is over 1000 degrees and Frank Ivy posted once anything heated to 900 will begin to emit visible light, so your secondary burn should glow if operating normally. I'm seeing my secondary burn tubes glow red depending on the wood I burn. My oaks don't seem to have much secondary burn action (they may still be on the high side of moisture content) but put a very dry elm or birch causes my secondary burn to have a field day.
  3. Sandor

    Sandor Minister of Fire

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    Use one of the those stove thermometers to take the guesswork out.

    Then you'll know for sure.
  4. Osburn1800i

    Osburn1800i New Member

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    Warren, I am glad you are posting this issue. I have same thing happened on my stove as well. I have four half logs ~ 5-6" in dia. in the stove insert and the stove burns very well even the damper is at the minimum setting. I am afraid to overfire the stove so I only load the stove up to about 75% full. It lasts about 4 hours then I open the damper fully to allow the charcoal to burn completely for about an hour. I haven't seen the jet flames coming from the tube holes yet but the very thin blue flames like gases burning on top of the woods.
  5. Jfigliuolo

    Jfigliuolo New Member

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    If your wood is VERY dry, it will give off volatile(sp) gases faster, lighting up the secondary burn. This is why they say kiln dried wood should NEVER be used in a non-cat (EPA approved, not the old tanks) stove
  6. wg_bent

    wg_bent Minister of Fire

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    Some of the really dry wood I have does do this more than some apple I have that hisses for a couple minutes. I think the Apple is too wet still. I do get the jets of burn going, but typically more out of the rearmost burn tube and less in the front. Sometimes I'll even get flames rolling down the front glass in a big wave. When I say the entire fire box is flame I'm not kidding. What gets me nervous is having a full load of wood like OSBURN1800i said and going to bed with that huge flame rolling away inside the stove. I've done it, but knowing how much flame and heat that stove is capable of does make me nervous. It seems like a stove thermometer is out since putting one on the "cook top" just wouldn't work. The owners manual is just flat wrong. If what they call the cook surface on that stove is 800 degrees, the interior of the stove would melt. That surface is a loosly attached shroud that directs the blower air down towards the floor. If that's 300 degrees I'd be surprised, since I can't even get water to boil on it in a small pan.

    If having the big rolling flames is sort of typical, then I guess I feel better knowing that's just the way these newer stoves work.
  7. Rhone

    Rhone Minister of Fire

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    Yeah, isn't that funny they call those things "cook tops" on inserts? They need to deem them cook tops, or warm tops. I have a Hearthstone insert that sticks out 5" and has a cook top. I thought wow! I can use it for cooking, boiling water, determine if I'm overfiring how neat to have one when the power is out. Didn't take me long to figure out something was up. It doesn't get hot, like at all. Yours happens to be a seperate piece with air blowing underneath. Mine doesn't have air blowing under it but appears to be insulated. So much for cooking with that insulation underneath! Having a very hot fire going it's not possible to burn myself on it or probably even boil water. Now, we use it for defrosting and warming, why I say they should call them warm tops.

    Not all inserts that stick out are like that. The smaller version of my insert doesn't have an insulated cook top, or air blowing under it and what I'd call a true "cook top", granted because of that it has massive clearances to the mantel above. Without your blowers on like during a power outtage at least your cook top will then get pretty hot and become useful when you can really use it. Mine, being insulated, I'm stuck.
  8. Roospike

    Roospike New Member

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    My P.E. summit does it too but does not get red hot at the top because of the flat SS that the box is made out of. Tubes would get hotter . Now with the secondary burn ....... the more smoke that the logs are giving off the more upper flame the secondary burn chamber is going to give off . Also you might be getting more flame from the back because that is where the air is coming from in the SBC . ( it least on the Pacific Energy stoves )
  9. Conrad

    Conrad New Member

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    With a good secondary burn going, my Lopi Liberty will run with cherry red tubes, and a sheet of flame down the glass. IMO, that's normal and doesn't seem to hurt anything. The top surface will be at about 500F, and it seems to be the optimal condition for this stove. The manual considers a medium burn to be 500-600F, and a high burn to be 700-800F. I can't imagine running it that hot- I saw 700 once and turned the air down a bit because it was just too hot. Even then, nothing other than the tubes would be even close to glowing. I heat the entire house solely with the Liberty, and as long as I can hit about 500F, there's plenty of heat in even the coldest weather. As for a low or overnight burn, I don't get much secondary burn with the air cut back that far, nor would I cut the air back until the wood was burned down, lest I stink up the neighborhood more than necessary. Efficiency won't be good with the air cut back. The key to everything is the wood. Last year I had very poor wood and thought I might freeze to death. Sometimes the fire would just plain go out! This year I got much better seasoned wood, and am having no problems. IMO, a modern stove that burns directly on firebrick, has to have good wood to work properly. My old stove had a grate and burned from the bottom of the stack up. It would burn anything, because the upper wood was dried by the flame below, and there was plenty of airflow. The modern stove is way more efficient, but needs to operate in a much narrower window of wood quality, airflow, and temperature. What I wonder about is your minimum air adjustment. Are you still getting too vigorous a fire, even with the air cut back?
  10. wg_bent

    wg_bent Minister of Fire

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    Well, It seems like when I have a very full load of wood, and a hot stove, all that wood giving off gasses all at once seems to be linked to a lot of secondary burn fireball. Clearly when the air control is at it's lowest, there's not much air getting in, since trying to get a fire started in the morning if the air's not open makes for a hard starting fire. Also, I get a hotter stove, more secondary, and wood goes faster if control is open more.

    Some wood seems to exhibit this more than others. Elm and Cherry seem to do this more than Oak, Apple and Ash. The clue here may be that the Elm and Cherry I'm burning were dead trees I cut and split, vs the Oak, Apple and Ash were live trees that were cut split and seasoned. Seems like seasoned starting from green wood may exhibit much better burn characteristics. I'm not positive about the correlation on this, and as I dig into the next pallet of wood over the weekend (Ash and Elm), I'll try to pay attention to the correlation of big secondary burn to wood species that I have in the pile.
  11. fespo

    fespo Feeling the Heat

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    Conard , I just bought a new Lopi Liberty about 2 months ago. In my owners manual in dosn't say anything about what temp to burn at. My dealer told me to run around 500 to 600. I was told about once a week to run it up to 700 to 800 for 10 mintutes or so to give it a real hot clean burn. The hottest I run up to is about 700. At 700 it look and feel like it going to melt down:) I too heat the whole house with it, I did but on two low speed and quite make shift blowers on . Have you had any problem with your? I have a leaking door or window seal that Im waiting for a replacement .
  12. Conrad

    Conrad New Member

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    I think wood is the key. Around here it's wet a lot of the time, and my wood isn't as good as it might be in some areas. My pile usually consists of some great dry pieces that ring like a bell when you knock them together, and some percentage that go klunk, weigh too much, and burn slowly. If you've got nice dry wood, split into smallish pieces, I can see where you might have a pretty good fireball when it gets going. IMO, you should always be able to cut the air back to get it under control, but that's a stove design issue.

    On the Liberty, I see no reason to do any weekly hi temp burn. Normal operation should keep it clean if the wood is good. My chimney guy has one, and says his chimney rarely even needs cleaning. I think the stove can handle over 700F on the top surface, since they say it can, but it will probably last longer if it doesn't have to. You also have the issue of measurement accuracy. When you run that hot, you really want to have a good handle on what's going on. Since the Liberty has no automatic air control, things can get out of hand quickly if you're not around to watch it. OTOH, it's hard to load it with enough wood to maintain those hi temps for very long.
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