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I'm considering adding a second floor furnace (32000 BTU) to our cabin, and wondering about how to hook up to the vent. As it is a retrofit, the usual venting piping isn't practical. There is an existing unit... can I simply hook up to it, and vent both units through one 4 inch vent? The two units will be about 10 feet apart.
You need to clarify your question(s).
You say your adding a unit- then you say there is an existing unit.
You don't say where they are located-
And either way- a 4" flue pipe will not meet code requirements- need 6". And that's assuming that we're talking about natural fuel furnaces and you're wanting to vent them together.
The original unit is at one end of a hallway connecting the living room to the bedrooms. The plan is to have another unit at the other end of the hallway, so it heats the bedrooms better. Both will run on propane. The original unit is, I suppose, about 50K BTU; the proposed second unit is 32K BTU, as it will fit between floor joists.
More: another venting option is to go outside via a foundation vent hole. The problem here is what to do at the top, where the roof overhangs about 2 feet. I don't want to punch a hole through the roof, fearing leaks, but I think code requires the vent pipe to be well above the roof, doesn't it? I don't understand why, exactly.
If this a new floor furnace, read the installation manual to determine if it can be vented horizontally to the exterior.
OK, I looked up the .pdf file for installation. So long as the proper slope 1/4 inch per foot is observed, the max length is 17 feet. We are 12, so that's OK. But once outside, how far up must the mast extend? I don't want to go through the roof, since with the new metal roof, the connections will get complicated. What is the applicable code, and what does it say?
Last edited by finnra; 04-16-2009 at 07:02 PM..
Reason: better explanation
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