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Toilet vent question - vent off the back of combo wye/45

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Nov 30, 2013, 12:30 PM
Toilet vent question - vent off the back of combo wye/45
First let me say thank you to all of the people who give freely of their time answering questions here - it has been very helpful to read through all of the older posts. I think I have learned a few things from it, but if nothing else I have developed a new appreciation for plumbers.

My question pertains to venting a toilet where the soil pipe is on the opposite wall, and the only place to vent is on the wall behind the toilet.

- I am under IPC 2006.
- I have some flexibility on elevation, but I plan to finish the basement so I want to use a compact design if possible.
- There are no other fixtures that will be connected to this plumbing.
- The soil pipe is 9 feet away, 24 inches lower, and has no vent nearby.

I have searched extensively, and while this would work well for me:

toilet flat vent

My understanding, though, is that the vent would either have to be 45 deg the whole way (no flat section) or it would have to be a wet vent. Making it 45 deg would increase the total elevation significantly.

I have come across suggestions that the attached image would work, but it seems suspect to me.


1. Would this configuration pass inspection? (2006 IPC)
2. Do I need the cleanout?
3. If this won't work / isn't up to code, do you have any suggestions for a configuration that would work while minimizing vertical space required?

Many thanks!

toilet vent

Dec 07, 2013, 04:03 AM
the image you posted was up to code
as long as your vent wye is rolled up on a 45 degree angle and the distance from the closet bend to the vent wye is 3x the diameter of the pipe... no co is needed.
the code states that the fixture itself, can be removed and used as a co..
altho....i like to install a wall co behind the tank....the same size as the drain piping....remove tank snake out drain
the fittings you have laid out on the floor, are not legal...your vent has to be behind the fixture being vented,,,so that the base of the vent can be washed out....if not it will stop it is laid out, the combination is not vented

go with the image you submitted
if you can not make that work..there are 2 other options to get a variance from the plumbing inspector, to not roll the vent of a 45 degree angle..ONLY if no other must get the variance 1st
second way is....

as the picture shows....your vent can be MAX..10' away from the toilet center of tee to center of 90....NOT a 10' run of pipe
i recomend this option ONLY in extreme conditions....a vent to far away, is trouble
but is legal
the fittings you would use...a 3" sanitary tee, a 4"x 3" closet bend
the tie in to your sewer you have provided no info so i have no comment

This message has been edited. Last edited by: Frodo,

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