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Author:
roundrightfarm (WV)
I have a situation where 3 bathrooms (one first floor and two second floor) each have their own vents (each 2" common vented toilet & sink) which will terminate near each other up in the attic. Is it a problem to combine these vents into a single one for the roof penetration? I would still have more total vent area going through the roof than septic pipe area.
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Author:
packy (MA)
sure... combine all into a single 3 inch thru the roof.
my code would have required that one of those vents was 3 inch all the way from below..
worded as 'one full size stack'..
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Author:
North Carolina Plumber (NC)
Here in NC, they all could tie together and still go out with 2" pipe. The vent only has to be half the size of the building drain.
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Author:
hj (AZ)
Half the pipe size, or half the pipe area? A big difference.
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Author:
North Carolina Plumber (NC)
Pipe size, 4" building drain = 2" vent. 6" building drain = 3" vent.
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Author:
hj (AZ)
Where I have been it has ALWAYS been about area, and 2" pipe is ONE-FOURTH the size of a 4" one, so it takes TWO 2" vents to equal a 4" drain.
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Author:
apcalabama (AL)
It is perfectly legal to combine your vents. This is called stack venting or buoyancy vent.Lower air pressure in any structure will always equialize through proper sized vents.Always be sure you have your san_T facing the right direction due to flow direction if stackventing.
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Author:
hj (AZ)
quote; facing the right direction due to flow direction if stackventing.
That is an "inspector requirement" and has absolutely NOTHING to do with the flow of a gas, which is what air is.
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