I am in the middle of a small remodel and have to install a run of 3″ B vent for the waterheater. This would be too small a job for any HVAC sub so I’m doing it myself. Couple of questions though:
The separate pieces of pipe interlock which I guess should be enough but they don’t seem to be air tight and they wiggle a bit despite the braces I’ve installed. Can I seal the joints with a (class 1) heating duct tape or is this not allowed.
Also, the storm collar isn’t exactly a tight fit around the roof jack/pipe either, what sealants should I use to make it watertight?
thanks
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The vent is an atmospheric system and need not be "air" tight. Any leakage will be into the pipe.
On the roof, any exterior grade sealant should work, however, the storm collar should be a tight fit.
Atmospheric system and need not be air tight - explain
The storm collar is a tight fit. Doe sthe caulk need to be able to withstand high heat?
thanks a lot
Atmospheric or gravity vent systems work by the same concept as a chimney. Natural draft caused by differences in density of rising hot gases creates a suction in the pipe that pulls the flue products up and out. The inside of the b-vent (when properly sized and run) will be at a lower pressure than the air surroonding it.
When you install vent piping systems like this you should get a complete copy of the manufacturer's install instructions. Usually they tell you what type of sealant to use.