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Moisture at bottom of vent stack at the hex adapter

743 Views 10 Replies 5 Participants Last post by  bruceb3
I have moisture gather on top of the hex adapter where the 2 " PVC vent stack goes into a 3" tee. The hex adapter has slots on top that are filled with water. There is no moisture on the stack pipe itself. There are copper hot/cold supply pipes in front, but they are not sweating either. What could be going on?


Additional information:

The bottom leg of the tee is for the toilet below, another arm goes at a right angle to the lavatory). 1/2 inch hot and cold supply pipes run in front. The wall cavity is on an internal wall.

The attached files show the top view with the slot in the hex adapter filled with water and the side view, with the supply pipes in front.

I run a hose through the stack on the roof, let the water run, but there was not leak detected.

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Might be vent boot on roof is leaking and water running down outside of stack. Run the hose around the vent boot and see if you get water inside.

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Thank you. There is no moisture on the outside of the stack all the way up, and we had a couple of storms the last two days. I am wondering whether it could be condensation but cannot figure out how old it is and from where. (I opened this cavity because we are doing remodeling. The water has been standing there ever since, a couple of weeks already.)
Thank you. There is no moisture on the outside of the stack all the way up, and we had a couple of storms the last two days. I am wondering whether it could be condensation but cannot figure out how old it is and from where. (I opened this cavity because we are doing remodeling. The water has been standing there ever since, a couple of weeks already.)
It's possible. Are any of those pipes hot water pipes?

Not likely, but it may be causing a condensation issue. As mentioned, my guess would be the rubber roof vent boot needs replacing. But you have ruled that out.

Looks like they scorched the pvc piping when they soldered. Lucky that didn't ignite and cause a fire.
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Thank you, again. There is something to what you say. I did notice the black marks (the house is 45 years old). The top/bottom pipes are hot/cold. I was soldering the cold pipe two feet to the left before opening this wall cavity (we were removing tile from the drywall).
The fitting with the slots is called a 3"x2" bushing
I see 3 possibilities for the water:
Condensation- you confirmed?
nail or screw hole- you confirmed?
dry fit 2" into 3"x2" bushing- can you see glue at that joint or confirm it is glued?
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Thank you. I am monitoring/checking all three possibilities.
Is it possible that soldering in one place can open up a solder joint two feet away and for that solder joint to reseal once cooled?
Is it possible that soldering in one place can open up a solder joint two feet away and for that solder joint to reseal once cooled?
2ft away? Not likely, even using 50/50 solder. But a joint can reseal
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I think I solved the puzzle. Earlier, I punctured a hole in a supply pipe two feet away, which released water that traveled along the pipe. I stopped the water, fixed the puncture by soldering a repair coupling. The next day, I was replacing drywall two feet away, where I discovered water in the bushing. All other explanations being rejected, water must have traveled along the pipe by capillary action to a tee, which acted like a drip edge, so water dropped down, creating a small puddle there.
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