External chimney offset

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countrybois

Member
May 2, 2008
127
NE Illinois
Why does Supervent not want me to offset around the eave? Is it because of the decreased draft or support issues with offsetting the chimney? I have a through-the-wall installation and would like to use the 15 degree offset to go around a 12" eave instead of cutting the eave and boxing it in. Is there really going to be an issue if I choose to go this route?
 
The main issue will be voiding the warranty. If they say don't do it, don't. If there is a failure or fire your insurance company may use this as a scapegoat.

M&G Duravent has this offset option for exterior installs and they sell a side brace kit to keep the offset elbows rigid.
 
Most brands of chimney offer the proper parts to do this. We usually offset around the eave, with support right at the offset, then straight up, and use a roof brace kit attached at the top of the pipe, just under the cap, for additional rigidity. If you offset out and then back in, the additional 2 bends can impair your draft. Also, most manufacturers specify the max number of bends. The less bends, the better, especially on an outside chimney, as they often run cool anyway.
 
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