Vent Pipe Routing

[Bogucki]

I think I know the obvious answer here, but I'll ask anyway.

Can a vent pipe be routed down? Due to a sloping roof line, once the vent reaches 6" above the flood rim, it will have to be sloped down into the existing vent stack. I know that liquid will fall either direction but gases could be trapped.

Am I going to have to make another roof penetration and put in a new roof jack?

 

[johnjh2o]

It's not the preferred way to do it but it will work as long as there are no sections of the line that can trap water.

 

[phishfood]

To further expand on what John said, make sure that the tee you install in the existing vent stack is oriented to that water from condensation can drain back into the existing vent.

 

[Bogucki]

Great. Shouldn't I use a wye instead of a tee?

 

[phishfood]

On a vent, it really doesn't matter. I mostly use tees because they are somewhat cheaper and easier to calculate the cut length of piping.