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Osburn runaway?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Bagelboy, Nov 15, 2013.

  1. Bagelboy

    Bagelboy Member

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    Had my 2400 insert running with the stovetop running around 400 degrees yesterday. Threw in about 4 or 5 pieces of wood and the top went to 600 degrees. This made my poor wife a wreck. Air control was all the way in. It's hard to believe there's no way to shut it down any further. My question to those who know: is the stove top or the liner in danger if it fires over 600 degrees? How can I shut the air down further?

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  2. etiger2007

    etiger2007 Minister of Fire

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    I love when my stove top is 600-700 lets me know im cooking effciently. My Osburn manual says anthing over 825 stove top would be considered an over fire. I think your just getting a tatse of what a beast you have. I get my stove top up to 500 ez just with the kindling load. I have overfired my insert before and the top started to glow dull red:eek:, my therm was pegged at 800 and was probably over 1,000. I think you need to stay around 600-700 stove top to burn clean, if you start hitting 800 for a long stretch then i would be concerned.
    Last edited: Nov 15, 2013
    dafattkidd and HatboroPaul like this.
  3. Grisu

    Grisu Minister of Fire

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    Please tell your wife that there is nothing to worry about. 600 F stove top is fine. In fact, that is an optimal temperature for running a non-cat stove to get a clean burn. I usually run my insert between 600 and 700 F after a reload. I get nervous and crank up the blower at 750 F; overfire starts at 800 F. If you have it only at 400 F most of the time you may not get a clean, efficient burn and accumulate creosote in your flue. Not really something that I would consider being more safe.

    To avoid having the stove run away from you after a reload rake all the coals in the front. That way the splits in the back will catch fire a little later. Dial down the air as soon as the splits have caught fire. Your stove and your flue are already warm; there is less reason to be concerned about creosote. When the stove is at 600 F and stays there with nice secondaries you hit the sweet spot. Just let it cruise like that all night.
    eclecticcottage and Beer Belly like this.
  4. eclecticcottage

    eclecticcottage Minister of Fire

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    That temp wouldn't bother me at all. I don't like to see it climb over 750. Check to see where the air intake is on your stove and make aluminum foil "balls" to stick in the hole (s) if you'd like to be able to cut it down completely. It's not a bad idea anyway, to do ahead of time, just in case.
  5. BCC_Burner

    BCC_Burner Member

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    Anything under 800 is just fine. I think the number 2 newbie mistake after burning wet wood is being way too concerned about overfiring the stove. It's a big metal box, full of wood, it's going to get hotter than your kitchen oven. Relax and take a layer off.
  6. Sprinter

    Sprinter Minister of Fire

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    I'd be concerned if it didn't actually (depending on how high the air is turned up).

    But I understand. I have an alarm set for 650 just to let me know it's up there and my wife freaked out whenever it did. (She understands now).

    Not many user manuals will give you an actual runaway number. It's good to know that under 825 is okay. Personally, I like to keep it under 650 under cruise conditions but I don't panic if it goes over now and then.
  7. Cynnergy

    Cynnergy Member

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    How are you measuring temps? Don't forget that if you have a magnetic thermometer, those usually are designed for use on single-wall stovepipe at a certain distance above the stove. No problems using them on the stovetop too (a temperature is a temperature), but the marked 'zones' on the thermometer for over-fire temps are not accurate for stovetop use.
  8. Sprinter

    Sprinter Minister of Fire

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    Good question. Inserts are usually pretty hard to find an accurate place to put a thermometer.
  9. etiger2007

    etiger2007 Minister of Fire

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    I use a Condar Medallion, these therms are disigned to read stove top temps. They are pretty accurate too, my inferred therm and the Condar are only about 50 degrees off from each other.
  10. HatboroPaul

    HatboroPaul New Member

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    I have the same unit Ed, and my experiences are exactly as you describe.
    etiger2007 likes this.
  11. Craig S.

    Craig S. Member

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    I should probably get a thermometer for my matrix insert. Any suggestions?
  12. etiger2007

    etiger2007 Minister of Fire

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    It's tough on a flush mount to measure the stove top, maybe get an infrared laser to read temps in tight spots.
  13. Bagelboy

    Bagelboy Member

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    True Cynnergy, I use a magnetic thermometer on my stovetop. However, I would think its at least close to being accurate. Also, everyone here seems to feel confident that the stove is not over firing at 600 degrees. My question is, why is it hard to control the intake when shut all the way down? Also, how can this be controlled?
  14. Bagelboy

    Bagelboy Member

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    Etiger2007, what was the stovetop temp when you overfired? Also, how have you been able to block air from coming in to the box?
  15. Cynnergy

    Cynnergy Member

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    Sorry if I wasn't being clear. I have a cheap-o Rutland similar to this: http://www.amazon.com/gp/aw/d/B000627RGM

    which indicates that 600F is in the overfire range. That isn't accurate. I get nervous if the stove is over 700F, but I am still a newbie. I believe that others on here have said to keep it below 800F. And if you have an insert and can't measure the temps very well I would listen to what others say rather than me :).
  16. Sprinter

    Sprinter Minister of Fire

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    How tall is your flue? If it's very tall, like around 30', your draft may be excessive which can cause this kind of problem. You'd be getting too much air and the control can't close the air down far enough.

    Also, how large and hot was the coal bed when you the put the additional wood on? If a coal bed is too hot on a reload, it can cause the new wood to offgas too quickly and this can happen. That often is what causes the runaways that have been mentioned here. Although yours was not really a runaway, you apparently had trouble getting it below 600.
  17. Bagelboy

    Bagelboy Member

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    The coals were very hot! I'm sure I placing 4 or 5 pieces on the coal bed created some problems, but, my chiminey is over 30 feet high. I would think that even with a hot coal bed, and with wood on the coals, the air intake should be more controlled. Now if it's hard to control the draft, what can I do to slow down the rate of burn?
  18. fitter9

    fitter9 New Member

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    in my short time with my insert i learned not to load on a really hot bed of coals. it will cause a runaway for sure. once it gets out of control its very hard to real it back in. i got alot of advice from people on this site that really helped me. my chimney is also over 30 ft. and has a very strong draft. it seems the colder it is outside the draft gets even stronger. the best advice i got was to block some of the air intake up with tin foil. that will slow down the draft. ive only had to do it twice so far when the temp dipped into the high 20s and it was windy outside. it worked great both times.
  19. cygnus

    cygnus Feeling the Heat

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    Hi Bagelboy.

    I think 600 degrees on the top of an insert is a problem. That is not actually the stove top. That's the temp of the air jacket running around the stove. The stove is MUCH hotter.
    Since there really is no good area to monitor the stove top temp, I have a thermo stuck in the air outlet. This is just gives me a relative temp to work with. I can't contribute to those, "I gone her cruis'in at 600 stove top" conversations because I have no idea what the actual stove top temp is but, I know that I'm crus'in when the output air is 175-225. At 150, the stove is cold and at 350+ I have a problem. I did buy a probe to install in the liner but I don't think I'll ever put it in. This seems to working OK.

    I experienced many overfires in my Osburn with the 30' insulated liner. It defies logic but, the air control only regulates the amount air to the secondaries. The primary is an open, uncontrolled hole. In my opinion this is a design flaw since it performs so terribly with a strong draft. My primary was sucking WAY TOO MUCH air due to a very strong draft and I was burning through huge quantities of wood. Once I found and obstructed the primary air intake I discovered what using a stove was supposed to be like all along. I can easily get 6 hours burns with half the wood. There is a promised land. Did you ever find the primary intake from this thread? http://www.hearth.com/talk/bookmarks/?type=post&id=1557168
  20. etiger2007

    etiger2007 Minister of Fire

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    My therm only goes up to 800 degrees and it was pegged and couldnt go any further, I think plate steel glows over 1,000 degrees. I did not block my air to my firebox, the reason I over fired was because I was an idiot and started closing the air down too late ( like 600 degrees) on purpose, Ill never do that again. Plus I got a whole new stove replacement from SBI due to the fact my door wouldnt seal right and Im sure that had some to do with it. My new insert is alot more predicable than the old one.
  21. etiger2007

    etiger2007 Minister of Fire

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    If your using a stack therm then yes 600 would be too hot, make sure you have a stove top therm, Condar medallion is a stove top therm line.
  22. etiger2007

    etiger2007 Minister of Fire

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    I have my therm directly on my stove top, the air jacket on our models are behind the surround.
  23. etiger2007

    etiger2007 Minister of Fire

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    Did you completely seal the hole or partially?
  24. Sprinter

    Sprinter Minister of Fire

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    The best place to restrict the air is at the secondaries if you can find the secondary air intake. The secondaries are where the trouble happens, and on most stoves the air is unrestricted there.

    Non-cat stoves were designed with moderate draft situations in mind. Unfortunately, strong draft situations suffer because no official accommodations were made for that. Probably modification of the air intake is not a officially sanctioned thing, but it's all that's left. You can put a key damper on the flue, but pretty impractical for an insert.
    Last edited: Nov 16, 2013
  25. BrowningBAR

    BrowningBAR Minister of Fire

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    This was not a runaway. The stove is running as designed. No need to try and smother it.

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