New internal chimney: venting chase to the room?

[DiscoInferno]

We're putting a second-story addition on top of the small section of our house that is currently only one story. Since it's on the opposite corner of the house from the Ultima and sometimes the Ultima can get a little overwhelmed even before the addition I figured I'd run a new chimney up at the same time for a second stove. Where the chimney goes up through the addition it needs to be framed in with 2" air space per code. This seems to suggest it will still get hot even through the inch of packed insulation. So here's the question, which came up in another thread recently but didn't get answered: is it worthwhile to put vents in the new internal chase, or even to use some sort of screening rather than drywall for the chase walls, in order to grab some extra heat? I'll need to use double-wall stovepipe because it's going to be a tight corner install (looking at the small Napoleon) so the internal chimney temp will be somewhat higher than with single wall.

Because my office in the addition is going to be up the stairs and through two other rooms I'm not sure even two stoves will heat it enough without some help. So I'm looking into adding in some ducts (with fire dampers! I don't want to restart that fight.) just above the new stove to the office floor. The cold air return in this case will be the stairwell, which already serves that function pretty well for the Ultima. I'm hoping to get enough natural convection to even out the temps, but I can always add a fan if needed.

 

[mranum]

Well after not getting an answer here on the board in the other thread, I asked my dealer about the vents. Not sure I completely agree but here was their answer.

Absolutely do not put vents in. In the unlikely event of a fire issue you are providing a fresh air fuel source that would make all the fire stops they put in meaningless. It also provides better access for rodents and other factors to enter the area. Also depending on how you use the stove, the rapid heating and cooling of the wood nearby eventually lowers the flash point of ignition.

So I guess I won't be putting them in.

Matt

 

[hotcookcpl]

Your dealer's answer makes a lot of sense. The reason to enclose the chinmey is to minimize any potential fire from spreading to the rest of the house. If there is ever a fire, having openings in the chase would certainly create a path for the fire to enter the rest of the house. Keep the chase as a fully enclosed chase.

 

[DiscoInferno]

Your dealer's answer makes a lot of sense. The reason to enclose the chinmey is to minimize any potential fire from spreading to the rest of the house. If there is ever a fire, having openings in the chase would certainly create a path for the fire to enter the rest of the house. Keep the chase as a fully enclosed chase.

Yes, but only if the fire started in the chase, which is unlikely if the chimney and chase are installed correctly (and near impossible if the chase was made of say metal mesh rather than wood). And if that did happen in an enclosed chase, then either it would go out, and you wouldn't know about the hazard until the next one started, or else it would eventually spread anyway and you wouldn't know until it had. So I don't see any actual safety benefit. Code as I understand it only requires that the chimney be enclosed in living spaces, and doesn't require the the chase itself be a firestop. It's not about fire safety but rather about people safety (from touching hot pipe). There would still be firestops in the floor and ceiling to prevent/retard vertical spread.

My question was simply if the outside of a typical insulated chimney gets hot enough to even bother trying to grab some of the heat.