New Shack, New Stack

[darkmachine]

In my old shack we used a 6x8 piece of square tube(steel) 1/4" walls for our chimney (2x6 evaporator, forced draft). Stack was about 16ft long, in my new shack I had an opportunity for a new stack. I came across a 20' piece of schedule 10S Stainless pipe 10" Diameter. I have about 14 feet from my floor to where the stack will penetrate the metal roof, some of that will be taken up by the height of the evaporator(32"), and some will be taken up with the height of the stack base(32"), the rest will be one solid piece of pipe. If i was using natural draft the rule of thumb is double the length of the evaporator for stack height, but in order to get out through the roof it has to be taller than that. Originally i thought i would just put the whole thing up but that puts me at close to 7 feet of stack above my roof. I started to think maybe I should trim it down, take maybe 4 or 5 feet off the top so the wind won't catch it so bad, any thoughts on that would be appreciated. That gets me to my next request for some input, the pipe weights about 18.7 lbs a foot...so taking off a few feet will help to manage it. I have two 3/16 cables run on pullies that i plan to use to suspend the stack over the base, any thoughts on that? here is a link to the bracket I fabricated to support the chimney https://photos.app.goo.gl/S56RkahyzRcyiAVU6

I put a lot of thought into this, but i don't want to miss anything, all input welcome

[Bricklayer]

Can the stack pipe not just sit on the base stack ? Is there a reason for the pullies ? Does it need to be lifted up for any reason after it is installed ? At 18.7 lbs per foot and 14 feet long that’s 262 lbs. not that much really. I’d feel better having it supported right down to the base then hanging off pullies and cables. I wouldn’t be too worried about the height to in have extending past your roof. The better the draft the better. And the further you are away from your roof and higher the better it is for getting sparks and embers away from your structure. If you are worried about it not neing sturdy enough above the roof line then install the cables out there. Our stack is 9 feet above our roof and there are 3 guy wires that come off it and attach to the roof to stabilize it.
And the good thing about your stack is it’s 1 piece.

[darkmachine]

The stack base i have won't bear the weight of the chimney, it's stainless but the gauge of metal is much thinner, it's 20gauge maybe. My fear is the chimney would crush it. If I don't cut the pipe down it's closer to 400lbs. 99% of the time the pullies would just be bearing the weight, the only time the pullies would be used is for install and cleaning.

[buckeye gold]

That was my first thoughts as well, that it would be a lot of weight for a a standard flue to hold up. You should brace it with some angle iron or something. I braced my triple wall with some strapping to the rafters.

[darkmachine]

I'm heading down there now, i'll add more pictures to the google album from my first post. I thought about building an angle iron frame to transfer the weight onto the arch. It would make me feel better if it was solid, however all the cables and pulleys are rated for way more weight than they will have on them. It's the last big thing holding up a test boil in the new shack.

[darkmachine]

Well the chimney is vertical! we did end up cutting off about 5' off the end(almost 100lbs), that still gives it about 64" above the roof metal. In the end we used a big extension ladder inside and moved the pipe up one rung at a time until it was in place. now i just need to finish up the plate for the stack to sit on, should have that fabricated tomorrow and it all setup for a test boil, I'm running out of time!