Ever since uI put up my chimney it would develope a nasty downdraft when the stove was cold. It only took a few seconds with a propane torch to reverse it. I would almost always get a little smoke back when adding fuel. After a lot of reading I attributed it to the close tall trees. The wind would come over them and down onto the chimney and force its way in.
So this year I pondered all summer for a way to stop it. I took the old cap off and modified it. The way it was it had a dome on it that was barely larger than the I.D. of the chimney. I took that off and built a 10" square flat top and put that on with the same amount of clearance from bottom of its edges to top of the chimney.
The down drafts are gone. The smoke backs are gone. It's hard to believe that just a difference of the cap could make such a difference in how the entire setup works.
Chimney Caps
- SWPaDon
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- Location: Southwest Pa.
- Hand Fed Coal Furnace: Clayton 1600M
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Thank you for posting the results of that modification. I too found that out years ago, and always made or purchased caps that were larger than the pipe..
- Lightning
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- Stoker Coal Boiler: Modified AA 130
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Be careful what you build it with. When I first started burning coal, I used a cheapy cap and it rotted and actually started to collapse onto the chimney which would be potentially dangerous to say the least. I've since changed to a stainless steel cap which is still like new.
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I already have a sheet of stainless to make another one. I wanted to see if it worked of if I needed something different before going to that extent.
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What about those whirrley caps. do those improve draft at all?