Still perplexed with an install I want to do that will, in effect, utilize class B vent pipe as a chimney.
The water heater ideally will be located with center of draft hood 14″ away from a 7″ thick exterior wall. I propose to place a 90 (the segmented flexible kind) degree class B elbow, with outlet end pitched up at least 1/4″ per foot, on the draft hood according to manf instructions, then extend a piece of class B vent pipe at the same angle through a listed wall thimble, and then to another 90 degree elbow that will point up vertically into another piece of class B such that the vertical run of pipe can be attached to the fascia board with a listed clamp. Then up about 5 feet, terminating in a listed rain cap.
A “through the wall” installation, yes, (which you nominally aren’t supposed to do with natural draft WH) but really “through the wall” into a chimney that just happens to also be class B pipe of the same size.
What is the diffence between this and a more typical installation where the class B enters a chimney or larger vent pipe that it shares with a furnace or boiler? What could possibly be wrong with this type of installation as long as it provides reliable draft and protects against fire by following manf recommendations re distance from combustibles, listed wall thimble, length and pitch of horizontal run, distance of vent termination from roof surface etc etc?
BTW, last winter I did a very temporary install of a furnace along the same wall, with the class B vent pipe just pitched up through the wall…pulled the insulation away a bit, and wired the end of the pipe to the rain gutter…no problems.
A chimney is a chimney is a chimney….or am I missing something here?
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A chimney is a chimney is a chimney....or am I missing something here?
Maybe"Thru wall venting" usually refers (at least in my area and in the literature) to where the flue terminates below the roof level, as opposed to what you're proposing, which is "through the wall" but continuing up.
You still have to consider possible condensation issues and be sure the flue terminates with sufficient clearnaces depending on the type of cap typically 1' or 2' above anything within 10'
Albert Einstein said it best:
“Problems,” he said, “cannot be solved at the same level of consciousness that created them.”
Your mileage may vary ....
I have no idea how gas exhaust compares to a wood fired heater where if the flue cools in it's rising height, the smoke quits going up. If the flue temp cools and inhibits draft, then carbon monoxide could be a problem.
Remodeling Contractor just outside the Glass City.
Quittin' Time
I have no idea how gas exhaust compares to a wood fired heater where if the flue cools in it's rising height, the smoke quits going up. If the flue temp cools and inhibits draft, then carbon monoxide could be a problem.
Exactly -just different temp ranges.
That's why GAMA now requires outside b-vent over a certain length be in an insulated chase.
3 pics attached from an inspection this summer -the b-vent serving the water gheater and furnace was (i) too long and (ii) not high enough above an adjacent wall.
697s shows the top of the b-vent, 699s shows some condensation marks atr an elbow, and 700s shos condensation by-products on the toip of the furnmace casing.
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Albert Einstein said it best:
“Problems,” he said, “cannot be solved at the same level of consciousness that created them.”
Your mileage may vary ....