I'm finishing the roof on the greenhouse, and am in the final planning stage for the RMH inside it. I thought I would get a normal flange for a chimney that they sell at lowes, but the one they have is for a shallower pitch than I have now, and one that WOULD fit might be $130 locally. This one would fit an insulated 8" section for going outside and up above the roof.
Wow - for some reason I did not consider it would be that expensive. I was also going to have to cross over and go out the north roof to leave the building downwind....
Thoughts please? What has everyone else done in this aspect of the build? Would I be better off building the RMH on the north side of the greenhouse for less materials? Is it better to have the chimney leave the building near the peak or downwind halfway down the roof OUT of the wind?
Thanks for your thoughts on this - it can be rather daunting at some points when you try to build it right and the only options are the ones that will pass inspection on a normal fireplace and are $$$$.
Matt Sorrells : For the Exhaust on a RMH that is being installed inside ANY kind of residence, you are stuck with a obligation to save some other future owner
of that residence from assuming wrongly that he could rip out your mud stove and put in a Blasto-matic 3000 wood stove, the only safe way to do that is to
build the final vertical chimney to meet ALL the rules and regulations for a safe final vertical chimney for a wood stove ! Remember many of the pieces
of the final vertical chimney will end up inside a wall or ceiling cavity out of sight, out of mind !
Exactly what your obligation for a RMH in a Greenhouse is, the final temperatures of the exhaust gases at the base of your final vertical chimney are such that
You have no expectations of the need for a conventional final exhaust Chimney, and all of the parts of your build are exposed for any one to see, inspect and
form a reasoned opinion of that chimneys fitness for some future purpose.
Also there is the issue of whether you have truly located the best placement for that chimney ! You may yet find that most days in the rest of your heating/
growing season the wind is coming from some other location.
Short version : Build it as you see fit, its only a greenhouse, and pass it on if and when on an as-is bases !
Just my two cents ! Big AL
Success has a Thousand Fathers , Failure is an Orphan
The closer to the peak you can have the chimney, the easier it will be to get consistent good function. Exiting "downstream" lower on the roof means you will need a taller pipe above the roof. Trying to keep the chimney out of the wind means you will get varying conditions as the wind eddies around the lee side of the roof, probably including back pressure at times. Keep it above the disturbances and have the wind blow straight across your chimney top consistently.
Location: Canton, NC
posted 4 years ago
Allen, 90 to 95% of the time the wind comes from the west or southwest. Not ALL the time, but the vast majority. Would it be better on the north side(downwind) side of the roof or ok on the upwind but above the ridge peak? And it is family land with no intentions of selling though.
Still better to have an insulated chimney outside the structure?
Matt; my greenhouse roof is a 12/12 pitch I used a regular 8" roof jack ,just off the peak. No insulated pipe at all just regular black 8" stove pipe as it passes thru the roof, it only sticks out 14" or so and the rest is 8" hvac pipe inside and stays warm . The temp at exit on mine is 130 F, the draw on a warm mass is excellent (blows out the lighter ) Use the cheap flange ,an uninsulated pipe will pass thru just fine.
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