Boiler vent pipe splice

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Llavey

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Can someone help me with a method to fix a leak in a 3" PVC pipe connection?


Twenty plus years ago a contractor installed a boiler when I remodeled my house. Two years ago, a different contractor installed a new boiler and reused the existing vent/intake. This winter I noticed a big wet spot in the ceiling and after removing a three-foot square of drywall I reached the leak. Condensation is running back to the boiler from the vent, ok except the connection between the vent pipe and the concentric vent was never cemented. The second contractor must have jarred things just enough for the unsealed connection to leak... Not his fault, he could not see it buried above the drywall in the ceiling of the garage.

Anyway. It needs to be repaired. I believe, but do not know if the metal reenforced rubber Fernco couplings are rated for inside sealed areas and can be used for vents? If I can use one of the those, great, easy, problem solved. But my guess is they do not meet code.

Neither end of the pipe is movable. I have about a 2’ working area. Both the Concentric pipe and the 3” PVC are solidly locked into place with spray foam insulation and whatever hangers the first guy used between the joists, which I cannot see. I could remove a foot or so of PVC, cement in a new piece to the concentric vent, but then what to splice the pipe leading back to the boiler? Whatever is used will have to slip over the PVC before cementing anything in. Thanks for your suggestions.
 

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John Gayewski

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The picture is not good.

But yes you can use a no hub coupling on a pvc vent.

Are you sure you can't run new vent piping? Pvc actually isn't rated for this use. It never was. Boiler manufacturers claimed it was OK to use pvc (and still do) but pvc manufacturers say not to. Boiler manufacturers are historically indifferent to good practice. If it can help them sell boilers as easier to install they will do it.

The pvc becomes brittle and discolored before failing all together. It's probably worth replacing all of it even if it's a big pain. Better than dying from co1 poisoning. Maybe you could find a new easy route to run pp pipe?
 

Llavey

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The picture is not good.

But yes you can use a no hub coupling on a pvc vent.

Are you sure you can't run new vent piping? Pvc actually isn't rated for this use. It never was. Boiler manufacturers claimed it was OK to use pvc (and still do) but pvc manufacturers say not to. Boiler manufacturers are historically indifferent to good practice. If it can help them sell boilers as easier to install they will do it.

The pvc becomes brittle and discolored before failing all together. It's probably worth replacing all of it even if it's a big pain. Better than dying from co1 poisoning. Maybe you could find a new easy route to run pp pipe?
Very good to know on the no hub connector! Thank you.

FYI: Replacing the whole thing would require removing over 20' of the double layer of drywall on the ceiling. For now, think I'll stick with this pipe repair and the 3' section of drywall damaged by the leak.
 
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