I recently saw a plumbing setup where a 2" pipe was run from a bend in the 4" toilet return. The 2" pipe bent upwards to meet the floor next to the toilet, where it was capped off with a removable cover.
In case of a clog, apparently the plumber uncaps and pushes air (or water?) through this pipe (or vent? valve?) to purge the clog.
First of all, what is the correct terminology for this apparatus?
And I hope it's not outside of the scope of the question to also ask does this thing function as a vent?
Will it have a one-way valve to prevent the elevated water in the toilet from rushing out when it's uncapped? (cap is level with the floor next to the toilet)
Here's an ugly sketch of the thing:
Best Answer
A capped opening in a sewer line is called a clean-out, usually they are a 4" long bend wye with a cap on one branch so you can pull the cover and run a snake down the whole length of the main sewer line.
In this case, a 2" pipe would be a good size to run a snake down to clear any clogs downstream from the toilet. I'd guess that somebody didn't allow enough drop in the sewer line and added the pipe to allow shoving the solids out of a long, level area.
Sewer Auger (Snake) or a Water Bladder Clog Buster just in case you ever have to use it.
No, it's not a vent.