6 Inch Liner in 7X11 Flue?

Lightning wrote:Ah ah ah Mr moderator.. gotta disagree partner... temperature is what makes the chimney draft.. although the chimney has 22 more feet of atmospheric pressure at the bottom, it is neutralized by having 22 feet less at the top.. your suggestion illustrates a gravity powered perpetual motion mechanism..

If all we had to do is stand a tall tube on its end to create a draft we would have the answer to all the worlds energy needs...

Go stand a 22' tube up and tell me what happens, I'll be waiting. Also read some Bernoulli. With 22' less pressure at the top of the chimney, the atmosphere inside of it will want to equalize. A temperature difference will increase draft, but without that it should still draft. I have never seen a 20' chimney that didn't draft cold. Mine is 15' and drafts well cold.

Not sure how you can create any serious power with what amounts to a hundreth or two pounds difference in atmospheric pressure. I'm sure the parisitic losses would eat any energy you could possibly harness from said powerhouse.

HUH????????????????

I agree draft pressure would be hard pressed to derive any usable amount of energy unless it was upscaled.. lol

I remember learning about Bernoulli in 6th grade science.. his principals have nothing to do with how or why a chimney creates draft..

Draft happens because heated air has less mass per volume which makes it lighter... its why hot air balloons float.. its why weather systems move around on our globe..

My chimney doesn't draft when its the same temperature as the ambient air because it can't, and there is no motivation for it to do so.. its 26 feet high.

But I don't want to hijack this guys thread with a physics debate, we can start a new thread for that. So rebuttal if you wish.. I spoke my piece.. peace out..

flyer,
May I suggest 'borrowing' the misses least favorite make-up mirror and , if the chimney doesn't have a cap, about 'high noon', with good sun light, insert mirror into flue and have a look. If it looks clean and healthy, fire it up. I think you said this is an exterior chimney. If so, even with minor crack, it probably will not leak into the house, as with an interior chimney. I check the flues on my chimneys(3) in the Fall, January clean out, and Spring clean out.
My misses lost a mirror about 30 years ago! I do not let her inspect the chimney.
Cheers

What coal stove are you connecting to this 7" x 11" chimney?

I am thinking the cracked tiles may be a non issue, but wondering if the size of the flue may hurt his draft if he is trying to run during moderate temps.

Anyone out there running their unit in a 7 x 11 flue to contribute their draft experience?

Buck stove 24. It is on the small side compared to many others.

Lightning wrote:I agree draft pressure would be hard pressed to derive any usable amount of energy unless it was upscaled.. lol

I remember learning about Bernoulli in 6th grade science.. his principals have nothing to do with how or why a chimney creates draft..

Draft happens because heated air has less mass per volume which makes it lighter... its why hot air balloons float.. its why weather systems move around on our globe..

My chimney doesn't draft when its the same temperature as the ambient air because it can't, and there is no motivation for it to do so.. its 26 feet high.

But I don't want to hijack this guys thread with a physics debate, we can start a new thread for that. So rebuttal if you wish.. I spoke my piece.. peace out..

http://www.engineeringtoolbox.com/natural-draught ... d_122.html

If chimmney draft was a result of temperature you would measure it with a thermometer. Since the effect is a direct result of pressure differences, it requires a pressure reading device to measure it.

According to the on line manual the stove holds about 55 lbs of coal. Ballpark of 60000 BTU's is my guesstimate from having a stove that holds about 80lbs rated at about 95000 btu's.

With it being smaller and having less surface area for radiating heat you may be burning it hotter which would help your draft.

If it was me, I'd zip tie my camera or a flip video camera to a rope and lower it down to see what the tiles looked like and to see if there is existing creosote that needs to be scrubbed. As mentioned, cracks in flue tiles are not a big concern with coal burning. If it is not blocked I'd use it by simply running a short length of flue pipe up the chimney and then blocking the area around the flue pipe with insulation and or a damper plate.

Be sure to connect a manometer to the flue pipe so you can watch your draft and as others mentioned a CO monitor with a digital display on each level. Maybe two on the level with the stove in case one is 'bad'. It is also useful to have a temp gauge on the flue pipe and the stove to watch your temps. I have a barbeque probe with a gauge in my flue pipe and use a magnetic gauge on the stove. Or you can get a ir temp gun to use for stove temps and torment the cat!!

Use a T at the turn to go up the chimney and put a cap on the unused end of the T so you can clean out the fly ash easily.

Since this is a new house / chimney for you, you will be experimenting a little to begin with to see what the burn / draft characteristics of it are. That is why the manometer is important so you can see actual numbers rather than guessing at what changes do to performance.

Welcome to the forum by the way and congrats on choosing the bestest warmest way to heat a house!

guys, temp and height affect draft. A proper stack should be built to produce draft without any added heat. The key issue affecting draft for any stack attached to a structure is height of stack in relation to the height of home, specifically the height of the highest interior conditioned space; that difference is the effective height of your stack. It's a little more complex than that, but that will get you thinking the right way every time without getting too complicated.

Everything mentioned about stainless liners is correct. It used to be masons would install a tile liner in a new stack with a crack in it and wouldn't give it much consideration, the stainless liner hysteria of course has changed that.