Connecting new PVC vent to cast iron vent

9 years ago

I have a 2" cast iron dry vent that runs from my basement vertically inside the outside wall to the roof. It was connected to an old basement bathroom, but I'm planning to renovate the bathroom completely.

I want to leave the cast iron vent line in place, but connect my new PVC vent lines into it so that they are vented all the way to roof. The connection to the cast iron is a right angle fitting screwed on the bottom of the pipe and the threaded female end sticks out parallel to the floor joist.

What is the best way to connect the new PVC to the threaded 2" cast iron female connection? I would prefer to be able T off of the pipe so that I can run to two vent lines coming off the fixtures.

Thanks,

Bruce

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Comments (4)

tjdabomb
9 years ago
http://www.plbg.com/forum/read.php?1,476612
Bruce in Northern Virginia
Original Author
9 years ago
The link you posted is trying to solve a more complicated problem than I have, since they are connecting in a drain. My cast iron pipe is only a dry vent and its completely supported by the house framing, all l need is an airtight connection to the PVC.

I know I could thread a short section of cast iron into the existing fitting and then use a no-hub coupling to connect it to the PVC vent. However, I want to know if there is some alternative solution I should consider.

Bruce
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bob_cville
9 years ago
If it is a standard 2" thread, you can get a threaded 2" PVC male adapter and screw it into the cast iron pipe with a generous coating of pipe dope or heavy duty teflon tape.

If it were a male cast iron pipe and a female PVC pipe, it would be pretty much guaranteed that sooner or later the PVC piece would break, but with a male PVC and a female cast iron pipe it should work.
jackfre
9 years ago
You could use a "mission brand" no-hub coupling. They make them to go from CI to pvc. It is easily done.