Roaster exhaust pipe precautions...

chast

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Jul 30, 2006
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If you are in a wood building you need a wall thimble. If you are using double wall pipe then you need to order the thimble according to the inner pipe not the outer. UL 103 and UL 103ht Type A is what you want to look for. Most wall thimbles will fit any pipe
 

AndyP

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Jun 9, 2014
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My double wall pipe made by nordfab came with a stainless 2 layer wall thimble to protect the wall. That being said you could probably rig up a wall thimble for a woodstove depending on what what wall is made out of ( and drywall is not flammable ). The outer pipe gets pretty hot to the touch where it goes into the wall. I think the real danger would be if the exhaust ductwork caught fire.
 
Ok I looked at the label and its 2" from combustible. Sry all, but good info here anyway! The inner/outer walls are wood. I'm thinking of running out the window as I think we may out grow this spot fast and I don't wanna do more work than needed if that's the case.
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Mr.Peaberry

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Aug 7, 2013
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Hi Daniel,

It's funny how you will get responses that open your eyes to a product you've seen before, but never knew what it's called, as in the case of a "wall thimble". I'm pretty sure I know what "special insulation" is though. My two cents? Treat the wood with a ceramic fire/heat retardant like chimney caulk or something of the sort, at least for a foot or two perimeter around the thimble as AndyP was spot on with his assessment of where the real danger lies.

Cheers,

Peaberry
 
Ok so I found the thimble on Amazon. My next question is, I need to get another 3' at the top to get it above the roof line. It won't be touching anything, so do I need double walled for the top piece or can I just go single walled regular pipe. Up to that point it will have passed through approx 10' of double walled.
 

chast

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The picture you posted is what I had to purchase to go through a side wall. Wallboard is considered combustible and even if you put up fire rated board the lumber is combustible. That thimble I believe will extend 10 inches and gives the n.eeded two inch air gap. On northern expresses site they have section that describe what is considered combustible. I found mine on eBay with free song brand new for 46.00
 
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