Toilet vent question

[freerangemike]

I am retiling an existing bathroom. When I removed the subfloor, I discovered that the existing toilet and shower were not vented, and that the toilet drain is under the subfloor instead of inside the wall. Can I use a 3x3x1 1/2 sanitary tee on the horizontal toilet drain line to add a vent for the toilet? It would look something like this picture I found online, assuming the 1 1/2" line is a vent. I believe this would be permissible if the vent off of the sanitary tee was less than 45 degrees off of vertical, which is not the case in this picture.

 

[Homerbplumbing]

So much wrong in that picture.

 

[Homerbplumbing]

You need a vertical pipe coming off of the two inch. The two inch should be on a wye not a tee. Tees are not aloud on a horizontal and all horizontal vents must be wet. Wet vent must be piped in correctly. That is not correct in your picture.

 

[freerangemike]

Thanks for the responses. Here's a pic of my existing and a sketch of what I am proposing. First, the toilet is less than 3' from the main stack, so if it was venting through the main stack, that would explain why it didn't have an independent vent.

The existing on the left has a separate sink drain with an unnecessary(?) p-trap where it ties into main stack. The toilet and shower share a drain through a Sanitary Tee. I don't think this meets IPC code, but I'm not sure. It does have a vertical elbow coming off of the tee outlet.

Assuming the main stack is not suitable to serve as the toilet vent, I'm proposing replacing the existing Tee with a 3x3x2 wye (my sketch shows a tee, but it would be a wye), with the outlet on top, tying into the sink drain to serve as the wet vent. There would also be a 2x2x1.5 wye along the vertical segment of drain to provide a common dry vent for the sink and toilet. This vent would tie into the shower vent above the ceiling, and has an existing separate roof penetration from the main stack.

 

[MicEd69]

While the soil stack does physically vent the toilet, it can't be the code vent for the toilet. But your plan looks good and per IPC.

But you cannot have two P-trap in a drain line. It is weird that that is what you have existing. So, when you change that drain to the shower, remove the P-trap that is at the stack.

 

[freerangemike]

Quick update and new question. When I cut into the old shower horizontal line, water spilled out, so it obviously doesn't have the slope it needs. So I need to adjust my plan.

Can I put a 2" Tee above my 3x3x2 wye so that the shower drain and wet vent are teeing into the same joint? While a tee would be easier, I can make it a wye if that is, as I suspect, required. I would put a backflow valve in the shower drain line as well.

Similar to this setup with all 2" pipes from plumbing magazine. (In the article, the author argues that the beginning of the wet vent establishes upstream so that the toilet is still the most downstream fixture: Taking a Close Look at Horizontal Wet Venting | Plumber Magazine.)

 

[Twowaxhack]

Fig 4 is correct.

Your drawing shows a 2x2x2 tee, that’s illegal and improper.

 

[MicEd69]

Your shower drain should be 2", and there is no need, nor would I recommended, to put a backflow valve in that line. And your sink drain is 2", but they are normally 1 1/2".

Assuming you have the room, you could come off the 3x3x2 wye you show that has the 2" coming up vertical and install a 2x2x1 1/2" reducing combo fitting with the 1 1/2" sink drain going into it. Then a 2" long radius 90 could be installed in the top of the 2x2x1 1/2" reducing combo fitting for the drain line from the shower.

A couple of cleanouts in the vent lines would be nice if you have access.

 

[freerangemike]

Another follow-on question...

Using the wye as planned results in a toilet flange that is 19" centerline to the side wall. I'd like it to be 15" from the finished wall so it is centered between the vanity and the wall.


Ferguson sells a 3" long sweep elbow with a 2" side inlet. I can't imagine why Charlotte would make such a junction other than to provide a vent for a toilet drain line, but I can't find anything that says such a elbow would be to IPC standards. Can I vent off of this 2" inlet if I immediately elbow vertically up?

 

[MicEd69]

First off, by code you need 15" on either side of the toilet centerline to a wall or vanity. So as you are 19" to the wall and need to move the toilet 4" to make 15", the current distance to the vanity appear to only be 11 inches. Is that right?

Heel-inlet or side-inlet quarter bends, or any arrangement of pipe and fittings producing a similar effect, shall be acceptable as a dry vent where the inlet is placed in a vertical position. The inlet is permitted to be placed in a horizontal position only where the entire fitting is part of a dry vent arrangement.

In other words, no you cannot use that fitting here.

Even if you could, how are you going to get the shower and sink drains piped up? A larger view of your layout would be nice to see where everything is coming from and what your restrictions are.