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submitted 1 month ago* (last edited 1 month ago) by CameronDev@programming.dev to c/diy@beehaw.org

Top comes out on the roof:

Not sure what happens below. Haven't gone under the house to inspect. Seems like a vent that travels through the wall space, but unclear why it would do that.

Any ideas what its purpose is?

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[-] everdream@social.tchncs.de 7 points 1 month ago

@CameronDev Sometimes these things are connected to the drain pipe of toilets. When you flush, they equalize the pressure and prevent a vacuum from forming in the pipe system.

[-] CameronDev@programming.dev 1 points 1 month ago

I'm fairly sure there is a separate pipe for that, which is on a different part of the house. Outside vent diameter is around 15-20cm, which is much wider than a normal sewer vent?

[-] Iconoclast@feddit.uk 3 points 1 month ago

In europe the standard drain pipe outside diameter is 110mm but the vent pipe sits over it so it's obviously thicker. However this is to create an insulating air gap between the vent and the drain pipe itself to prevent it from freezing here in a cold climate. Depending on where you live this might not be a thing.

Drain vent still remains my guess for what that is. Every house has atleast one but it's not uncommon for there to be 2 or 3 of them.

[-] CameronDev@programming.dev 1 points 1 month ago

Its also not near the rest of the plumbing, so I don't think so.

Australia for what its worth, but freezing isnt really an issue here.

[-] termus@beehaw.org 2 points 1 month ago

Since you've ruled out a lot of other things. My only thought is if you have a basement it could be the radon mitigation system.

[-] CameronDev@programming.dev 2 points 1 month ago

No basement either, and radon mitigation doesnt seem to be a thing in Australia? I was wondering if it was for ventilating the under house area, but that just seemed odd.

this post was submitted on 03 Aug 2026
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