Garage utility sink stub out question

[Panicman]

Hello, I’m installing a sink that sits flush against my garage wall to a stub out provided by the contractor when the house was built a couple years ago.

I’m not familiar with the top pipe that emerges from the wall at a 45deg angle. I’m assuming it’s there to vent(?)

What is it and what do I do with it?

thanks in advance!

 

[Geofd]

I have ever seen that 3rd pipe I think I would open the wall make sure there is a vent on that piping then cap it off in the wall

 

[Jeff Handy]

Maybe it’s a poor man’s urinal, haha.

 

[frodo]

remove the co plug ,and cut the cap off of the 45 degree angled pipe
run your tape measure UP the threaded co opening
and verify it is a 45 bend or a wye
if it is just a 45, install another 45 and install an aav

 

[Panicman]

remove the co plug ,and cut the cap off of the 45 degree angled pipe
run your tape measure UP the threaded co opening
and verify it is a 45 bend or a wye
if it is just a 45, install another 45 and install an aav

That all makes sense BUT- why would I need to install an additional 45? Why not just install the aav to the existing 45 behind the sink?
Thanks for the replies!

 

[frodo]

you could probably get away 45 degrees with a Hunter AAV ( one of my old designs ) as this valve operates by a spring being compressed, where as all other AAV,s operate by gravity.
You just need to be mindful as to what you install

 

[SHEPLMBR]

Do you have pictures of the back side of the wall?

 

[Panicman]

Unfortunately, no. I believe the backside of that wall is at least in part behind sheetrock inside an interior closet. I took pictures of the plumbing and wiring when the home was being built, but totally missed the backside of this stub out when I did. Kicking self...

 

[SHEPLMBR]

Unfortunately, no. I believe the backside of that wall is at least in part behind sheetrock inside an interior closet. I took pictures of the plumbing and wiring when the home was being built, but totally missed the backside of this stub out when I did. Kicking self...

I would make sure that piece isn't busted off of something that the drywall may be hiding.

 

[Jeff Handy]

Isn’t that upper pipe going to be right in the way of the sink fitting flush to the wall?

 

[TomFOhio]

I would open that wall in the front and see what that pipe does as like Jeff said that pipe is going to be
in the way of the sink. If it is a wye in the vent you can cap it, but if there is no vent then you can move
the pipe over and then put your aav on.

 

[Panicman]

Thanks again for the replies.

This home is less than 5 years old and I was in it everyday during construction. Nothing in there is broken, I would have noticed that on my obsessive walk throughs.

Cutting the wall open there would be tricky because that whole wall is covered in plywood under the sheet rock.
The sink I am installing has a backsplash built in that positions the unit far enough away from the wall that the unit sits flush. Here it is placed in front of the existing stub outs:

Here is a pic that shows how the stub outs fit behind the sink:

 

[Panicman]

This plumbing is far removed from the other plumbing in the house, and it only makes sense that it is a vent. I installed an Oatey aav, and everything is working fine.

Thank you all for the help.