Is this VC Aspen C3 OAK install ok?

[mycelianhollow]

Hi all,


Got a Vermont Castings Aspen C3 stove installed as part of a renovation. I've learned a ton from this forum already, as I was selecting the stove and planning the install!

Here it is right after the install. The flue up and out from the stove is within spec for that pipe (the pipe is ULTRABlack and only requires 6" clearance; this install is 9-10" from the drywall) and the stove itself (also requires 6" from combustibles per Vermont Castings). The stove is resting on ceramic tile, which is on top of cementboard. Those all seem to be ok. (right?)


My question is the outside air intake. The connection point to the stove is below the firebox, as you can see from the pic. But the installers put the pipe penetration out the wall of the house is at the top of the firebox.


I've seen lots of comments here and in other forums that say an OAK should not be at or above the height of the firebox, including the penetration out of the house. VC's installation manual doesn't *say* the OAK should go below the firebox but the two example installation illustrations they provide both show exterior wall penetration below the firebox. I've found what looks to be a Vermont standard allowing an OAK to be above the firebox if, among other things, the chimney top is at least 15 inches above the outside air intake point. Our flue and chimney go straight up, no bends, and is 25 feet high (roof is a steeply angled A-frame-ish type roof so the chimney had to go wayyyy up).

My concern is whether there's a risk of the draft reversing and the OAK becoming an exhaust (read: fire hazard). If it matters, it's a very air tight house (aiming for 450 cfm @ 50Pa, #IYKYK ).

In these circumstances, should I have the OAK lowered so it goes straight out the wall under the firebox? And/or should I really reduce the intake duct length?


TIA!

 

[begreen]

The manual is correct and the guiding document. That VT standard is the exception. Here is the whole section:

R305.4.3.2
The exterior air inlet shall not terminate to the exterior higher than the firebox and the combustion air duct shall not rise vertically within 18 inches of the firebox.

Exception: Where woodstove or fireplace is installed below grade (in a basement), air intake is permitted to terminate above the firebox if the combustion air supply point is below the firebox and the combustion air intake point is greater than 15 inches (381 mm) below the top of the chimney.

 

[mycelianhollow]

The manual is correct and the guiding document. That VT standard is the exception.

I hear you re the manual is the guiding document. Which is why I’m trying to decipher what it means (if anything) that VC shows two illustrations with the OAK below the firebox out the exterior wall, but doesn’t say anything about that height requirement?

If OAK height vs the firebox were important, shouldn’t they have said that just like they explicitly specify clearance to combustibles?

 

[begreen]

Agreed, the documentation could be better. They took the pictorial approach instead of explicitly saying the intake must be below the firebox floor. Both illustrations in the manual show the intake below the firebox floor. The Vermost code also states this.