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I Forge Iron

Chimney Design Question

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Hello All,

I have been searching for a less expensive chimney solution and want your opinions. The cheapest I have found is 300+ dollars.

First the requirements. I want no less than twelve inches in diameter and need 20 ft or so to complete the job. The pipe is running horizontally from the back of the forge, through a stick framed wall, and up the side of the shop. I am planning to pour a small slab to mount the chimney to and plan on running mounting straps back to the wall.

The Idea. It came to me in the shower this morning that if you can build a wood stove out of 55 gallon barrels you should be able to build a chimney. I have a local source for barrels (some stainless). If I remove both ends and stitch weld them together, then seal the seams with furnace cement will it work for the main stack? I would then use a piece of 12in pipe for the horizontal and fab a cap from the lids. I will also be able to fab an ash door in the bottom. This would give me a large diameter stack that is stainless and easily replaceable if it rots out.

The Question. Will it work? If there are interior rings where the cans join will they interfere with the draft? Will the furnace cement hold during any movement of the stack due to wind and weather? How will the weather affect it?

Thoughts and comment needed!

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22" might cause some draw problems. I'd look into the small drums that greas comes in, their about 12", you can cut the drums, so you have a sheat of steel (running a heavy pick up or tractor over the ribs will solve that problem) then role the sheet the other way. It will give you a tube 10-11" and 5-6'. Unless the stack is UL rated I think code is going to want it 3" from the wall. They are going to want a ceramic themble or double (even triple wall) trew the wall. Might be less trouble to go threw the roof, besides single wall outside in cold weather can sea ritually hamper draw.

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It'll work but you'll need a really BIG fire to provide enough heat to draw.


Why is a chimney costing so much? Does it really need a concrete pad? I haven't checked prices lately but I do know 12" is pretty spendy. Are you planning on triple wall except where it passes through the wall? The off the shelf hangers are generally good unless the stack has more than a few feet free standing over the roof line. I really prefer to use 1/2" electrical conduit flattened on the ends as guys rather than cable. We get the occasional 100+mph. wind "event." "Event" is what whoever makes the decisions prefer to call wind storms so as not to scare off folk wanting to buy homes.


A really good thing to add is a "T" at the bottom running from the horizontal section to the vertical stack with one leg pointing downwards. This allows warm air to move upwards along one side of the stack and allows the cold air to move downwards on the opposite side. It also lets any water to drain without entering the shop.


Regardless of what I suggest, check with code, your insurance and folk who know. Much better safe than sorry.


Frosty The Lucky.

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