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Making an old stove emit less emisions

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by wg_bent, Feb 25, 2006.

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  1. wg_bent

    wg_bent Minister of Fire

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    There's a lot of old stoves out there that are great heaters, they just don't meet EPA requirements due to lack of secondary burn technology of today's new stoves, or a designed in catalyst. Seems like this would be a prime opportunity for a device that would be placed immediately after the stoves flu output that incorporated a catalytic combustor. Is there such a device? I know Eric added one to his furnace, but is there such a beast that works for stoves?

    Just think of all the old Jotul 602's pre-EPA, or VC Intrepeds and so many others, that could get a renewed life with such a device. I would suspect that a rule or two would need to be changed to allow for installation of an EPA approved stove, or a Pre-EPA stove with the addition of a catalytic converter device in the flu (properly installed of course)

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  2. jabush

    jabush Feeling the Heat

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    I looked into after market combusters for my old (coff-coff smoker-coff-coff) stove. The one for my application looked like it replaced the stovepipe damper. I thought "that's a good idea!". But the more I read about cat combusters, I found that they get very hot and it made me kind of nervous to think of my stovepipe getting in the 800+ degree range for hours on end.
    For now I just try to burn my stove as cleanly as possible until I can upgrade. Unfortunately, I had to spend my stove money making my current setup safe to operate after I had it inspected.
  3. precaud

    precaud Minister of Fire

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    Warren, I completely agree. But even without using cats, some of those stoves can be modified to burn cleaner and perform even better than their modern counterparts.

    Case in point: In the early 90's I spent quite a bit of time improving my Jotul 602's performance (and getting crinks in my neck from staring at the fire through the air inlet holes...). I fashioned a vertical plate, placed at the front of the baffle and contoured to it, to force the exiting flames/smoke/air to mix before exiting the firebox. On the door's inside casting, I blocked off all of the upper holes except the two center ones. And I placed 3/8" stainless steel rods along the top of the baffle to stop the flames from leaking out along the sides. These mods certainly helped make combustion more complete on all but the lowest firing rates, and improved the heat output. Most of the time, there is no visible smoke coming out the chimney.

    It could probably be improved still further by adding some sort of secondary air source at the top-rear of the firebox.

    Don't get me wrong - I like the new F602... it's keeping me warm as I type... but the amount of heat the modified old 602 gives puts the new F602 CB to shame. Now if only the old one had a glass front...
  4. begreen

    begreen Mooderator Staff Member

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    First rule for an old stove is to keep it in good working order. Rebuilding my old 602 made a world of difference in improving it's burn times, heat output and I believe it was much cleaner burning after the rebuild. We almost never could see smoke coming from the stack. Second thing would be to burn properly. There is a great thread on Tom's site - ChimneySweepOnline, that shows the difference in emissions between the stoke it and damper it right down method and the burn hot to throroughly char the wood, then damper down method. http://www.chimneysweeponline.com/hoarticl.htm
  5. wg_bent

    wg_bent Minister of Fire

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    I wasn't thinking of the cat in a stove pipe exactly, but more of a bit beefier device that had the cat in line.
  6. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    There were a lot of cat add-ons back in the eighties. The problem was that they just burned the smoke after it left the stove providing no additional heat except in the pipe/chimney. Ya need a combustion chamber in the stove to recover the heat.
  7. jabush

    jabush Feeling the Heat

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    Actually, what I had in mind when I looked into aftermarket cats was the cleaner burn as opposed to more heat. My stove is more than this house needs, but it was here when we bought the place. I'm guessing when I finally upgrade, the new stove will be about half the size of the Huntsman.
    If I had some confirmation that the stovepipe could handle the high temps for long periods I would rethink installing a cat for a test run. Other than not being able to view the fire, the only thing I don't like about my stove is it's not clean burning. Of couse my family and my wallet are enjoying the "free" heat!
  8. elkimmeg

    elkimmeg Guest

    Why did these add on cat fail Brother Bart aptly explained it but there are other factore they soon dissapeared
    the premise seem like they were a good idea for cleaner burning.
    #1 the restricted the flow of draft
    #2 could not be used in weak drafting stoves
    #3 required frequent cleaning

    If one burnt colored newspaper junk or wet wood the cats world colg as accumulations built up the stove would not draft.
    The stoves themselves were not designed to have draft reductions. Since the pipe is the heat exchanger little heat is stored
    in 24 ga steel plus its location the heat went up the chimney with the draft. For the most part they were ineffective
  9. jabush

    jabush Feeling the Heat

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    That makes sense. I'm nixxing the retrofit cat idea.
  10. precaud

    precaud Minister of Fire

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    To quote from the article: "Fuel has been added to the woodstove, but no one has touched the controls for an hour and a half... Then the draft is shut down all the way for several minutes."

    On any stove I've ever used, burning it for that length of time with the primary air wide open will pretty much burn down the whole load... it's not a great example. But it does illustrate that burning smaller, hotter fires in any stove will result in cleaner burning.
  11. begreen

    begreen Mooderator Staff Member

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    Exactly, it's realtive to the stove size and design. If you left the older 602 wide open for 1.5 hrs, it would have first turned cherry red and would have exhausted the fuel in less than an hour.
  12. elkimmeg

    elkimmeg Guest

    Ant the #1 reason addon cats to the flue will not work? in a cat stove the draft is bipassed protecting the cat till stove
    Teemps reach or exceed 500 degrees where cleaner burning is taking place. Then the seconday path of exhaust is opened by closing the primary exit. There is no way to achieve this ina single pipe exhaust. So when fires are first started they produce the most polutants and clog the cat. If the wood is not that dry also moisture has to pass threw the cat. There is noway to close off the inline cat in the single flue,, for temps to rise and cleaner burning takes place, before engaging the cat. Same problem when adding wood. A lot of smoke and polllutants are released into the cat before temps are high enough for secondary cat light off. It does not take that long to clog it up Given this situation I doubt the inline cat will ever light off but act as a draft reducer. Probably reduce the stove's effeciency when the clogged cat restricts draft.
  13. wg_bent

    wg_bent Minister of Fire

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    o.k., read my lips (sorry I just couldn't help myself.. he he)

    Think new device here. incorporates a cat, secondary burn chamber and a bypass. and it all fits in line with the stove pipe. What I'm talking about is a small woodstock soapstone stove that comes after the old 602. O.k. so in thinking that through...I guess it's just time to melt down the old stove and buy a new one.

    Sigh, well, Elk that "need of a bypass" combined with "a way to extract the heat" all seems to kill this idea. Too complex
  14. wg_bent

    wg_bent Minister of Fire

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    LOL....(I hate you guys!) LOL :lol: :lol: ;-) :coolsmirk:
  15. elkimmeg

    elkimmeg Guest

    I did not look at it that way.. I tried to remember what transpired when these flue pipe cats
    were intruduced and why they failed. I was not trying to wear Warren down.
  16. Sundeep Arole

    Sundeep Arole New Member

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    Just an idea - but thought I would throw this out. Use a add on cat, and then one of those stovepipe heat exchangers to extract the heat from the cat. Then you could tie it in to a DHW system or a hydronic floor heating system.
  17. pgmr

    pgmr Feeling the Heat

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    The one I've looked at online (Catalytic Damper) is just that - a catlalyst mounted like a damper. When it is not in use (during stove startup or reloading), it is turned parallel to the flow of smoke, allowing it to pass by the cat. Can't see how the cat would plug when little, if any, smoke is passing through it during bypass mode.

    I considered one of these a few months ago to clean up my flue gas, but the biggest problem I saw was that I would lose the ability to just sweep directly into the stove. The cat would have to be removed before every sweeping and some kind of bag arrangement attached to the now open pipe. If the unit reduced the need to sweep to once a year, it might be worth it. I just don't want to spend $200 to find out that it doesn't.
  18. elkimmeg

    elkimmeg Guest

    I figure its time to examine my flues ,get on the roof, I just as well aught to brush it out for the piece of mind.
    I do remember when theses were popular in the 80"s I'm not saying all will fail. Will the burn clean enough to
    eliminate cleaning your flue? I don't think any here could say for sure. $200 is a gamble I would rather clean my own flue and know for sure. Must be doing something right, 2 stoves operating going on 30 years no chimney fire yet. Couse I inspect them often and clean it to start the season burn dry wood and clean them mid season
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