Advice on existing clay-lined chimney

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!

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.

Is a higher chimney better or worse?

Hi -

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

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)?

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.

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?