Wood stove outside-air duct material
AdamPNW
| Posted in General Questions on
Hi all,
I’ll be installing a wood stove with an outside air adapter for a 3” or 4” duct that attaches directly to the bottom of the firebox. This duct will need to be routed under a slabless floor (earthen floor over foamed glass aggregate) to the outside ~15’ away.
I’m worried about the durability of standard metal duct material. Also it would need to be air/water proof. Would plastic pipe work for this situation, or is this a fire hazard in some way (even though I can’t imagine heat going down instead of up).
Any similar installation experiences out there? Thanks!
Adam
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Replies
Think it needs to be metal. Galvanized will last decades. Downdrafts happen
gusfhb,
Our code acknowledges that. If the combustion air is connected directly to the appliance, it needs to be non-combustible.
I can't speak to the "can it be plastic pipe" (although my suspicion is that that will NOT be acceptable), but I wanted to mention that you CAN get stainless steel flue pipe and ductwork, but it's very expensive. If it's acceptable, thinwall stainless steel PIPE not DUCT may be cheaper, but you have to get it from mechanical supply houses.
Bill
Single wall stainless flue pipe is not that expensive for a short run like this and comes with all the elbows and fittings you need. Make sure you locate the outside air intake location that it won't get covered by snow/leaves/vegetation. No stove combustion chamber is air tight, so it might also be worth it to add a shutoff on the air supply (something like a metal dust collector gate valve) to be able to close it off when the stove is not in use.
Thanks everyone, great feedback. I’ll price out the stainless flue pipe, and the gate valve seems like a worthy addition.