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by muffyj
6 months ago in Design Dilemma
Range hood exhaust tied into an existing chimeny?
My old farmhouse has a chimeny not used anymore by the furnace. THe chimeny is behind a kitchen wall right where the stove is. Can a range hood be tied into this chimeny to exhaust out the cooking smells?
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BeautifulRemodel.com Hi muffyj,

All building codes that I know of say no, you cannot. However, its my understanding that in some areas they will let you do this IF you install a properly rated metal vent liner all the way from the exhaust to the roof cap, AND permanently block off the other chimney penetrations, so the next home owner doesn't inadvertently begin using the flue for the furnace etc.

Common sense tells us that the fireplace flue was intended for a very different use, kitchen exhausts contain grease and moisture, and the build-up of both both can cause masonry degradation as well as being a fire-hazard.

It would be much safer and wiser to run the vent through the wall and in the shortest possible distance. If this is a challenge (I would imagine it is if you're asking the chimney venting question) then try posting some photos of your situation with dimensions. This will help us in being able to make alternate suggestions.

~Steve
6 months ago · ·
muffyj Thank you Steve, what you said makes sense imagining grease and moisture traveling all that way up the chimeny. I will call the city where I live, Eden Prairie MN, and ask them about this situation. Is it possible to vent to the outside when the stove is on an interior wall?
Thanks for your reply.
6 months ago · ·
feeny Just so you know, muffy, what Steve described is exactly what we did. Right next to the place where our old range was located, in the middle of a 1920's house, was a hidden chimney (completely separate from the fireplace chimney) that had been originally used to vent an incinerator in our basement. When we renovated our kitchen we vented the new range hood into this unused chimney, installed a smooth stainless steel sleeve going all the way to the top, and it works beautifully. Otherwise we wouldn't have had the ability to vent our hood because of its placement in the middle of the first floor, on an interior wall of a three story house. The stainless steel sleeve was not cheap, however, and the whole job had to be approved by the city's planning board.
6 months ago ·
muffyj Thanks for the info feeny, your house sounds like mine. Was there a damper installed at the top of the chimeny? And did you use a mechanical contractor to install? If it worked for you that gets me excited that it might work for me. I did call the city building inspectors office and they said it could work if properly done. Please let me know about the damper.
6 months ago ·
feeny To be honest I can't remember for certain about the top damper. It has been three years since we finished the kitchen renovation. Would a top damper involve having to open it manually in some way each time we use the vent hood (as we do with the regular damper for the fireplace)? If so, then the answer is no. If it's something more automatic, then possibly yes. All I know is that the city had a number of very specific requirements to make it work, and we complied with all of them. Our GC brought in a specialist to do the whole chimney sleeve installation--not sure whether his official title was mechanical contractor or not. It added well over $1,000 to the renovation, but we ended up downgrading from a Wolf SS vent hood (to go with our Wolf range) to an identical one made by Broan for almost $2,000 less. So that paid for the chimney work. Sorry I can't remember more details--I kind of left those up to our contractor, who was incredibly meticulous about all the engineering issues (he had an engineering degree, but didn't end up using it when he went into the family business). So I felt confident about the result.
6 months ago ·
muffyj Thank you so much. You are a very big help. This may possibly work out after all.
6 months ago ·
BeautifulRemodel.com Hi Muffyj,

Because the vent run is long, it would make sense to use a roof (chimney) mount exhaust, which has an integrated motor and damper (It sounds as though this may be what you're considering perhaps?) The hood exhaust will be far quieter with this method, and because you'll be running venting up through the chimney any way, the electrical can be installed at the same time (MC type).

I would recommend that you use a licensed HVAC contractor for this, as there are many details that need to be exactly right for this to work correctly.

Best wishes with your project!

~Steve
6 months ago ·
BeautifulRemodel.com Also, regarding venting to the outside when the range is on an interior wall - there are a few ways to do this. Ideally you can fit the vent in between (and parallel to) the ceiling joists above the kitchen. Not always possible, because the joists can run the opposite direction frequently. (You probably don't have ceiling or floor trusses because of the age of your home, so that's not really an options...) Soffits above the wall cabinetry are a common way to hide the vents, although these can make the room look shorter when the ceilings are under 9ft

I've also hidden the vent at the top and inside upper wall cabinetry. The cabinetry is customized to fit around the vent, then a decorative shroud added once the vent is installed. (So when you open the cabinetry all you see is a clean box made from cabinetry material, up at the top)

Hope this helps,
Steve
6 months ago ·
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