chimney/flue questions

[franz frippl]

I'm installing a woodburning stove that accepts 6" stovepipe. Is there any advantage to using an 8" chimney or can I keep the chimney at 6".

The chimney is not yet built.

[christian_pare]

If it's a prefab, I would stick to 6". The chimney should be the size of the stovepipe. If it's a masonry chimney, the only reason to go bigger (7") is if you want to more easily reline the chimney further down the road.. But, a bigger chimney will create more draft, thus a little more heat lost to the exterior.

I just installed a new woodstove in my home that came with a 6" stovepipe exhaust. We had a 7" brick chimney built for it. It works fine. I wanted a chimney that could be relined easily (in ~30 so years).

Christian

[franz frippl]

Thanks. This is for a small (20x24') cabin with loft. I'm thinking of a prefab metal chimney out the exterior wall. I know this is perhaps not the best arrangement but I prefer not to punch a hole in the new roof.

[christian_pare]

It will work. Just make sure you follow all the manufacturer's recommendations on the prefab chimney installation (READ: clearances).

=3D)

Christian

[S. Barker]

It is possible to create too much draft. But going up just one pipe size won' t do that. I have a fireplace insert with an 8 inch outlet and my chimney is 12 inches square. Sometimes when i open the stove doors, it just goes ape! Also the smaller pipe will stay cleaner due to it's running hotter.

s

[hallerb]

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s running

the effective size of a square or rectangular chimney is the largest circle that can fit inside, so your 12 inch square isnt as oversized as you might bellieve

[Joe]

Bad choice, poor draft and drainage problems. A roof isn't sacred, and a prefeb near the peak will be perfect for your installation. Follow code for height, use the right flashing exactly like the directions (under the shingles upstream and over the shingles downstream) and install a storm collar. The only real trick part is cutting the elliptical hole so the pipe is nice and straight going through the roof. HTH

Joe

[terry]

ors, =EF=BF=BDit

t's running

You mean???? a) 12 by 12 =3D 144 sq. inches. b) Pi x (r squared) =3D 3.142 x (6 x 6) =3D 113 sq. inches. If and when you install a metal flue liner within an existing masonry chimney? c) Eight inch pipe. Pi x (4 x 4) =3D 50 sq. inches. smaller pipe might be better in some circumstances and stay hotter for less soot deposit?

[hallerb]

e:

et and my

doors, =EF=BF=BDit

it's running

airflow near corners is poor, thats why i said what i did

[S. Barker]

Given that theory, (which doesn't make sense) then you could get a 12" pipe up my flue. And the area of a 12" circle is over twice that of the area of an 8" circle. AND the area of the 12" square is almost THREE times the area of an 8" circle. So, believe me, a 12" flue makes a hell of a lot more draft than that of an 8" pipe. This was confirmed when i finally dropped 8" single wall pipe down my chimmey and hooked it directly up to the stove insert. No more raging away when i open the doors.

but thanks for playing,

steve

the effective size of a square or rectangular chimney is the largest circle that can fit inside, so your 12 inch square isnt as oversized as you might bellieve

[S. Barker]

Yes, you got it.

steve

[John Galbreath Jr.]

Do not oversize. A 6" round has 28 square inches. An 8" is almost double at 50 square inches.

From another reply you made. It is not hard to go through the roof, and is a lot less expensive. Plus, you get the benefit of the heat off the pipe inside.