Chimney for a forge

[Doug C]

After digging through all the posts here there seems to be a consensus about using at least 10 inch pipe for the chimney of a forge. All the stove shops around here have 8 inch or less. Where would I find the 10 or 12 inch pipe every one feels is best? Should I use insulated, galvanized versus stainless? My budget is limited.

Also I was thinking of doing the chimney in the fashion done by Uri Hofi at his school with the square side draft chimney with the round pipe going up off of that.

Anyone got a good design they want to share?

[ThomasPowers]

Well I went over to the Habitat for Humanity Re-Store in Albq NM and bought 2 10" diameter by 10' long spirial seamed vent pipes for US$4 a piece.

I plan to build a side draft set-up as they work real well. I will either modify a piece of stainless pipe for the forge side piece or make it from thicker mild steel depending on what I can scrounge.

Note that typical stovepipe can be assembled from multiple pieces to get the width you need, saw a 4" and 8" or two 6"s or a 4 and a 6, etc.

[jimbob]

try a 12"-14" covert ...like they put in your driveway

[Frosty]

Galvy culvert is expensive stuff.

snapping two sections of 6" or 4"+6" sections along the seams works dandy.

Frosty

[waianvil]

doug, for my pipe I went to menards and got the insulated pipe the one you run through the wall ane pulled out the inside pipe then used the outside which is 10 inch in diameter
the cost then isn't to expensive that way

[unkle spike]

Home Depot sells galvanized sections of 12" vent pipe, check near the ductwork, that is where I got mine, wasn't too expensive.

[Dave M]

I would also check local building codes, in some areas wood and coal fired stoves are required to have double or some times triple walled pipe:mad:. Some code inspectors consider coal forges to fall under coal stove guide lines as they are coal fired and give off heat. In my neck of the woods I need at least double walled pipe for my wood stove, double walled pipe is $185.00 for 8" pipe by 48":(. I would also check your local HVAC shops for pipe. I am also building a chimeny system like Hofi's with 10" heavy galvanized pipe and I found that a local HVAC shop can make it for short money and that it was a heavier gauge then the home depot pipe. I did like the the galvanized culvert suggestion because I see that stuff listed on craigs list all the time becuase of construction co. over runs.

[Dave Leppo]

I used a few pieces of 12" galvanized pipe, and an elbow, which followed me home from work. these formed the horizontal portion. Continued the main vertical stack with 12" duct made from 2 pieces of 6" duct snapped together. this was a much lighter guage metal, but it should last a while. at the forge, the galvanized part that's over the fire is a removable hood, not part of the horizontal pipe, which stops behind the big rusty plate. (the grey disk thingie behind the vertical pipe, on the exterior wall, is an exhaust fan discharge, which I always run when working, especially in the summer time)

Edited July 30, 2008 by GOATMAN

[Doug C]

Thanks for all the info on this. I have some good ideas on how to get started now. where the pipe passes through the exterior wall what is the best way to safely do this to avoid fire? Is there a preferred method? I am not sure I want to let the town in on my little secret. I live 1/4 mile out of the town center and zoning law in town are a bit stricter. They may frown on a coal forge more than my neighbors.