What's the purpose of this DWV valve?

[kleonard (Kevin Leonard, CPI/CMI)]

2 YO house.

With the exception of a pressure test, which only happens at construction, what’s the purpose of this valve?

Seems like an expensive way to test as opposed to installing caps over the top of the vent like I usually see.

[mwilles (Martin Willes)]

Nowhere in the vent portion of a DWV system is a valve allowed, with the exception of an air admittance valve. Must be homeowner installed for some reason.

[sbergman2 (Shane Bergman)]

Maybe they put together the stack with random leftovers, they didn’t have a connector but they had an extra valve…

[kleonard (Kevin Leonard, CPI/CMI)]

@mwilles

Nowhere in the vent portion of a DWV system is a valve allowed, with the exception of an air admittance valve. Must be homeowner installed for some reason.

Interesting, I didn’t know that.

Thanks Martin!