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"Cat stoves do very well with smoldering fires."

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by soupy1957, Sep 24, 2010.

  1. soupy1957

    soupy1957 Minister of Fire

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    This quote comes from another thread............I don't understand this statement:

    "Cat stoves do very well with smoldering fires." I thought that "smoldering fires" were a bad thing, no matter what?

    It seems illogical? What am I missing here?

    -Soupy1957

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  2. Hanko

    Hanko Minister of Fire

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    I dont think your missing anything, I agree. Smoldering fire BAD.
  3. grommal

    grommal Feeling the Heat

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    Used to have a cat stove. What the post means is that, as long as the cat is lit, the fire in the main firebox can smolder, and the cat will reburn that smoke. This works well up to a point. If the smoldering is too intense, it can produce more smoke than the cat can burn as it passes through, so you still get a dirty chimney and a nasty cloud for your neighbors. A long, cold smolder can also fail to keep the cat lit long enough, and when it stops working then you have an old-fashioned smoke dragon. As a cat ages, the activity of the precious metal catalyst layer also decreases, so a well-used cat gets into trouble more easily than a brand-spanky new one.

    So, as long as the smolder produces an amount of smoke that the cat can handle, and as long as the cat stays lit to burn it, you're ok.
  4. Hanko

    Hanko Minister of Fire

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    at some point and time, I think ILL try a cat stove, probably a BK for my shop.
  5. Pagey

    Pagey Minister of Fire

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    Sounds like grommal summed things up pretty well. I'll agree that my non-cat stove doesn't deal with a smoldering fire well at all, but I can see where a cat stove, with the firebox heated up and the cat well into the active zone, could reburn the smoke from a smoldering fire where a non-cat would not. I believe the cat can reburn smoke at 500F or so, whereas the temps inside a non-cat need to hit 1100F or so for reburn.
  6. soupy1957

    soupy1957 Minister of Fire

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    In our home, we have a non-cat stove. That being said, I thought that a Catalytic Coverter was an inert object. A filter that simply processes the smoke going thru it, like a furnace filter does. Believing that to be the case, the statement, "......as long as the cat stays lit to burn it, you’re ok" doesn't make sense.

    The "Cat" is more than just an inline filter?

    -Soupy1957
  7. Pagey

    Pagey Minister of Fire

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    Well, my understanding is that the cat is a ceramic honeycomb treated with special metals that allow the smoke to combust at much lower temp (500F) than in a non-cat stove. I can't speak for whether or not the cat is actually "doing" anything, but once it reaches 500F, that puppy is burning smoke!
  8. branchburner

    branchburner Minister of Fire

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    I believe burning smoldering fires excessively will require the cat to be cleaned more frequently to continue performing well.

    An argument for catalytic stoves is well summed up by Pagey: "the cat can reburn smoke at 500F or so, whereas the temps inside a non-cat need to hit 1100F or so for reburn." When I wish to dial-down my non-cat and still burn smoke in the less-cold months like Oct, Nov, and April, the best I can dial down to is 1100F in the afterburner. Still very hot. Otherwise, I'm just running my high-tech stove like any other old smoke dragon.
  9. vvvv

    vvvv New Member

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    http://hearth.com/what/cat.html
  10. SolarAndWood

    SolarAndWood Minister of Fire

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    You have to light the cat off in the beginning of the burn cycle. If you don't get the fire hot enough to light the cat, you will billow smoke right out the stack until the wood in the firebox is gone. Once it is lit, however, it will burn very low for a very long time with zero smoke escaping the stack. This process takes me less than 10 minutes on a typical reload, much longer from a cold start which only happens a handful of times per year. Grommal and I had the same stove previously and his statement about keeping the cat lit is very true for that stove. However, the BK has proven to be a very different animal that is quite capable of clean 24+ hour burns continuously through the season with none of the nonsense the other stove required.
  11. Patapsco Mike

    Patapsco Mike Feeling the Heat

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    If I open my BK in the middle of a burn, it is always a smoldering fire. It's a smoky mess inside the stove, something that never ever, happened in any of my non-cat stoves (when I was burning properly). But thanks to the active cat, that smoky mess gets burned up and is a big part of what heats my house.

    The ability to throttle down the air to the point where the fire is smoldering- while still operating at peak efficiency- is why you can get such crazy-long burn times out of a cat stove.

    BUT- not all cat stoves can do this well, you need to have a grasp of how a cat works (need to get the cat fired off before you can get away with any of this) and if your wood is not properly seasoned it will not work at all. So it's not going to perform if you aren't paying some attention to what is going on.
  12. oldspark

    oldspark Guest

    I might have bought a cat stove but was afraid the wife might have trouble with it.
  13. SolarAndWood

    SolarAndWood Minister of Fire

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    Because it only gets loaded once a day, my wife rarely opens the door and our daughters aren't allowed to even touch the door handle. On the other hand, all three can and do adjust the thermostat on the side of the stove any time they want. Even the little one knows that she can turn it up to 3 if she gets up in the morning and thinks its a little cold. As a result, we get at least 15 minutes more sleep than we would otherwise.
  14. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Okay Soupy. That quote was from me so please allow me to explain what we do and how our stove does its job.

    With a cold stove or on reloads, we bypass the cat (turn it off). This is done very simply by moving a lever from the down position to the up position (Some on this forum thinks this is complicated!). The reason we bypass the cat is to bring the stove temperature up to about 500 degrees (interior). That temperature is needed before the cat will light. Once the stove is to that temperature we then move that lever down (or turn it on. Complicated?). This is at the same time we dial down the draft.

    In short order the cat begins to do its work (burning the smoke). Most times it will give a very bright red glow. When that happens the flame will change and it is pretty to watch. Usually in a few minutes we will dial the draft down further. Each installation might be different and no doubt the type of wood makes some difference too. With our stove we usually dial the draft down to around .25. That is with a scale of 1-4. So you can see we have the draft almost shut and in fact there are times when we do have it shut and the stove still burns great.

    I'll never forget the first time I got up during the night and was shocked at what I saw. Whenever I do get up during the night it is normal to check the stove. Well, I went to the room with the stove and I thought the danged thing had went out as I could see no flame at all. Yet, the house was toasty warm. As I got to the stove and looked in the glass I could not see even one spot of red coals! Well, the glass was not dirty but what is going on? There was this red glow I could tell was coming from the cat area so I bent down to look and that cat was really bright red. The stove top temperature was sitting at 650 degrees! Well, how can this be? No flame. Just a smoldering bunch of wood with the cat burning the smoke.

    That has happened so many times it is old hat now. Most times we will have either a small flame or shortly after the reloads we get what looks like the Pits of Hell itself. But the flame is really pretty with it lifted above the wood and it appears to be rolling. A sight to see indeed.

    So naturally many will wonder if we have some big time problems with creosote. I'm glad you asked. We heat 100% with wood using only the Fireview. Our chimney runs up the outside wall of the house and is not surrounded by a chase. We have burned wood in this stove for 3 full winters. We have got approximately a cup of soot from the chimney. That was a year ago when I cleaned. We did not clean after last winter and the chimney still looks clean.

    We have cleaned the cat twice each winter but this year will probably be once during the winter and again when the summer cleaning happens. Cleaning the cat is very simple and takes 2-3 minutes.


    So with the way the cat works, we can and do burn with smoldering fires and it works very well.
  15. begreen

    begreen Mooderator Staff Member

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    Perhaps a better way to put it is cats do well with a 'low' fire after the catalyst is hot enough to burn off the wood gasses.

    If the cat is prematurely engaged when the cat is cool and the fire is smoldering, it's going to get gunked up, right along with the flue.
  16. Flatbedford

    Flatbedford Minister of Fire

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    You could say that, but with regards to operating a Fireview, it would be far to complicated. Mine is just like Dennis said. Bypass cat, open draft, start fire/reload, wait 5 or 10 on reload or 20-30 minutes for proper temp, close bypass, close down draft, walk away, enjoy soft heat for 8 hours or more, repeat. Set and forget.
  17. fjord

    fjord New Member

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    Best use explanation yet ! Good job. :exclaim:

    The extra step ( 1 only ) and extra care checking the cat "light off" at reload is exactly why stove engineers designed non-cats to satisfy EPA particulate requirements. The platinum or paladium coating needs a high temp.
    Users just did not bother to use the cat stoves as speced.

    As BS explained, once the cat is "lit" to burn the non combusted smoke products, it will continue for the cycle.
    Think of the catalyst in your vehicle, it lights immediately due to the high combustion temps. No need for any "reload" higher temperature delay.
    It's the extra steps and care that many cat users didn't do. And, as he said, at first it's a kick to run out to see the "no smoke" from what some are calling a smouldering fire. At first.

    For you cat users remember that the combustion life of cats is ~ 12,000 hours of burn time, whether you clean it, bathe it in hot vinegar (yes, the Corning method), use unseasoned wood, or leave it.
    Don't throw the cat out (many do) , and burn without it. The cat stoves are designed for use WITH the catalyst.
    For 24/7 wood heat the 12K hours is for us close to 2 years of burning. Still, cats are nice long steady heat. The last catalyst bought last year was the steel cat from SUD-CHEMIE in Mass.

    While we enjoy the Oslo, the burn cycle is not as long, or steady. Those burn tubes in the Jotul will stay hot enough to gas off, but nothing like the efficiency of our cat stove. Same wood, same spaces, similar insulation,same bodies. Over the 4 years with the Oslo and the Encore, the Oslo uses ~ 1/4 more wood for the same BTU's. The unscientific experience for 100%, 24/7 heating in northern Maine.
  18. soupy1957

    soupy1957 Minister of Fire

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    I GUESS I "get it" (lol) Some very detailed and educational info here.

    I started it as a seperate thread only because it was somewhat off topic in the OTHER thread.

    The long and the short of it for me is............I'm happy with my stove WITHOUT a CAT, but I can't say from all the info, if it is truly BETTER to have a CAT or not. I guess that's one of those preferentially subjective discussions that has no definitive ending, as long as there is more than one person on this planet.

    -Soupy1957
  19. begreen

    begreen Mooderator Staff Member

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    My cat is happier with a stove.
  20. Pagey

    Pagey Minister of Fire

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    But is your cat happier IN the stove? :lol:
  21. Todd

    Todd Minister of Fire

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    When Woodstock comes out with their new hybrid cat/noncat next year you can have the best of both worlds and end the debate.
  22. ddddddden

    ddddddden Minister of Fire

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    It's not pre-EPA voodoo. It's cold hard science. www.thefreedictionary.com/catalyst http://en.wikipedia.org/wiki/Catalysis IMO, the woodstove is a very good application for this technology. . .really a shame that only a handful of stove manufacturers use it, the typical reason stated being that Joe Sixpack would find operating a cat stove too complicated. Seriously? Too complicated because you have to open a bypass at startup and reload? Funny, I read nothing but praise for the similar damper bypass in the Lopi non-cat. Is there any stove that can be operated properly by dumping in wood and walking away? No, you have to open the draft for, say, 20-30 minutes, get a good burn going, then reduce the draft. What's the big deal about closing the cat bypass when you reduce the draft?
  23. weatherguy

    weatherguy Minister of Fire

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    Took me a while to get used to that too, I would check it before I went to bed and would see norhing and thought it burned out, then I lean down and look up at the cat and see it bright red and glowing.
  24. ddddddden

    ddddddden Minister of Fire

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    Double post. Doh!
  25. North of 60

    North of 60 Minister of Fire

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    this is what I have going today at this time. Loaded at this am. Some pine and poplar 3/4 load 4hrs into burn and smoldering. Will get 12 hrs min for sure out of it. High temps above the cat but 400F at the rest of stove top locations. Been doing this since day one in mild outside temps. YR5. CAT still purring along like a kitten.
    Not a inline filter Soup. A heat source that smoke fuels.

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