Advice on existing clay-lined chimney

burnt03 Posted By burnt03, Nov 11, 2011 at 1:57 AM

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  1. burnt03

    burnt03
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    Oct 30, 2011
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    Have a masonry chimney on the outside wall of my home, two flues. The flue leading downstairs is about 6x10 ID. Probably about 20-25' high

    Don't have a stove yet (looking for a deal on a used one and lurking on the forum) but would a EPA stove with a 6" outlet work OK with this size chimney?

    Thanks in advance!
     
  2. Jackfre

    Jackfre
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    Oct 3, 2011
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    Exterior chimneys are the worst. Pardon me, oversized exterior chimneys are the worst. I cannot say that a system you would select would not work, but it is oversized and the flue will be cold. A good chimney liner will do wonders for your overall system efficiency and comfort. Masonry chimneys are basically 11th century technology venting 21st century appliances. A liner brings them all up to date...a good liner that is. If you look at the gas and oil codes in Canada they basically tell you you cannot use any masonry chimney under almost any circumstances. Granted, it is a different fuel, but I think they are on the right track.
     
  3. begreen

    begreen
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    I'm going to say maybe. It's worth a try as long as the chimney is tile-lined and in good condition. But the difference between 20ft and 25 ft is significant and may be the determining factor of whether a stainless liner is required or not.
     
  4. burnt03

    burnt03
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    Oct 30, 2011
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    Is a higher chimney better or worse?
     
  5. begreen

    begreen
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    It can be better if there is a couple 90 deg turns in the connector at the beginning of the smoke path. But worse for creosote collection in a colder chimney, especially at the top of the flue.
     
  6. zzr7ky

    zzr7ky
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    Jun 12, 2006
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    Hi -

    I would plan on lining the chimney. There are ovalized flex liners. Ovalize rigid liner slightly (creative use of the hydrolic splitter?).
     
  7. burnt03

    burnt03
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    Oct 30, 2011
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    Bringing this old thread back to life....

    Had a sweep in today to sweep and do an evaluation on the existing chimney, looks like it's in good shape.

    So my question is, what problem does the oversized chimney present? I seem to remember reading:

    1) Results in cooler temperatures going up the flue, get more creosote production

    2) Draft problems?

    Regarding #1, would that problem be eliminated or reduced if I had a cat stove (blaze king)?
     
  8. begreen

    begreen
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    Nope, wrong assumption. The Blaze King will idle along providing yet a cooler flue. However, with an insulated liner in there like DuraLiner, I think you will be ok as long as the wood is nice and dry.
     
  9. Waulie

    Waulie
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    I would try it as is. You can always put a liner in later if it's not working out. Just keep a look out for creosote. I would price out a liner now so you know what you might have to spend in the near future.

    FWIW, my dad is running a 6" outlet cat stove on a 7X11 ID chimney. His is about the same height as yours, but it is interior. Works great for him! I would expect quite a difference with an exterior chimney, though. Bottom line is that since your chimney is in good shape, it can't hurt to try.
     
  10. burnt03

    burnt03
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    Oct 30, 2011
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    Loc:
    Peachland, BC, Canada
    Thanks for the replies

    So a cooler flue results in more creosote production and a poor draft.

    Is there any way to check my draft as it sits (no stove, just a thimble through the wall), like lighting a match and seeing if the smoke is heading up and out or pushed in?
     
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