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bosnbob7
Water leaking from inside gas vent stacks
bosnbob7

During a hard rain last week, I noticed water leaking thru ceiling in Laundry room. I climbed into the attic and noted that the roof was not leaking. The water was leaking out from a bend in the exhaust stack from the water heater. I also noted that the same was happening from the gas exhaust stack from the AC / Gas Heater in the attic over the garage.

Two issues:
1. Should these be sealed to prevent gas from going into the attic/garage or does the upward flow prevent this? and
2. How do I seal these to prevent water from entering and leaking out on the ceiling? Roofs are steep.

Jack
Re: Water leaking from inside gas vent stacks
Jack

Generally you do not need to seal the joints on the flue pipes.

You can install a rain cap on the top of the pipes

Jack

Benjamin
Re: Water leaking from inside gas vent stacks
Benjamin

It is also very possible that the water is condensation coming from the appliance

dj1
Re: Water leaking from inside gas vent stacks
dj1

I once had a stubborn leak like this. It was the vent flashing.

Re-do the tar around your flashing, install a cap over the vent and make sure it's secured so it won't get blown away.

Benjamin
Re: Water leaking from inside gas vent stacks
Benjamin
dj1 wrote:

I once had a stubborn leak like this. It was the vent flashing.

Re-do the tar around your flashing, install a cap over the vent and make sure it's secured so it won't get blown away.

dont tar it that is just a bandaid that makes it harder to fix the real problem when it comes back. Fix it for real

Fencepost
Re: Water leaking from inside gas vent stacks
Fencepost
dj1 wrote:

I once had a stubborn leak like this. It was the vent flashing.

Re-do the tar around your flashing, install a cap over the vent and make sure it's secured so it won't get blown away.

If the flashing was bad, the water wouldn't be coming from INSIDE the flue pipe.

It's either a faulty rain cap, or condensation. Since you indicated this happened during a hard rain, you probably have a faulty rain cap. There are a few different styles of flue cap available. The one that JLMcdaniel showed is the least expensive variety. I'd recommend one that is designed to prevent birds and wildlife from entering the flue. Some are more resistant to rain than others.

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