Combustible Outside Air-Intake (New Slab Construction)

[jhambley]

Curious if anyone has any experience or advice. I need to install an outside air-intake in a new concrete slab foundation.
The intake will be used to provide combustible air to a wood stove in the center of the house.

Thanks in advance for your assistance.

JH

[MountainDon]

I did a through the wall vent for our wood burner. That was easy. It is a great idea, especially if you build a tight structure.

Under the slab... the first pitfall that come to mind is what if water gets into it? Condensation? I guess it should be sloped to the outside.

Is it possible to draw air down from the attic or are there no nearby walls? If there's an upper floor air could also be drawn through a sidewall between joists, then down an inside wall.

[John Raabe]

I would check with the stove manufacturer or their local Rep. A direct vent to the stove will be the best if the inlet exists. They can advise on size, material, slope, how to route through or under the slab, and local issues such a where the inlet should be and how screened. For instance, in snow country the inlet will have to clear the expected deepest snowfall, or, in some cases the inlet might open from a carport or porch that might be covered.

While this involves some research, it is well worth the effort for the energy savings and the safety factor in helping to avoid backdrafting of flue gases.

[rick91351]

MountainDon I like your idea of locating a vent high - like under an eave.  One could then cover the opening with a eave vent cover to keep the insects and dust out.  Air then would be pulled through a duct between floor joists;  then down between the studs to the manifold into the stove.   Going that far I would question if it would it be able to draw enough air without assistance without an inline fan or something of that nature.  But then I think a person could always try it, if it worked great.  If it didn't it would be a fairly easy fix; so long as you could get to the ducting.

[Redoverfarm]

My stove has a direct vent to the outside.  I had laid a 4" Sch 40 (electrical)pipe through the block when I laid the flue.  You might check with the individual stove manufacturer as this is usually a option for the kit that has to be attached to the stove to configure it for fresh air intake rather than a damper type.  It was basicly a box configuration that bolted on with a 3" nipple.  I just put a reducer to 3" at the wall to the stove.   On the exterior I used a flashing material which I drilled a pattern of several holes.  Does very little for the bugs only bigger critters.  But if the bugs make it in there is no place where they can exit to the room.  Nothing had to be changed on the stove and it operates the same (mechanically) but it did improve the efficency of the stove.