I find it hard to draw a picture of plumbing lines, but I made an attempt to draw what I am trying to do. I think if I can get the following question answered I am good to go. Can I place a vent between a toilet and shower drain and keep water in my shower trap when the toilet is flushed?

I am doing a complete remodel, but the toilet is furthest away from the soil stack, then the shower is closer to the stack. There is already a vent between the soil stack and toilet drain, so I would like to use it. This would be the layout: Toilet starts the 3" drain, 20" downstream will be a TEE on its side and angled above centerline (the vent runs through a joist out of this TEE and then into a TEE that then runs straight up through the roof, other side is left open for next door bathroom toilet vent mentioned below), 14" downstream will be a 3x2 wye that allows my shower drain to come into the line, and the drain then continues on down to the soil stack.

My concern is that when the toilet flushes as the water goes by the shower drain it will pull water out of the trap. If so, I will then take a line after my shower trap through the joist, up the wall at least 48", then TEE into the vertical vent line already running. It would be nice if this wasn't needed.

ALSO, as you see in the picture, another bathroom sits right next to this one. A new 3" drain starts with the toilet, a WYE is turned on its side and angled up 8" downstream (angled part goes through 1 joist and into the open TEE mentioned above where the vent makes the vertical shot through the roof) and the other side of the WYE continues the drain down to the soil stack.

Sorry for making such a long post. I am a novice at best and feel like I've read just enough to be dangerous. Both bathrooms are laid out WEIRD, so the sinks and one of the showers all have their own vents, hence the reason they were not mentioned here.

Where do you live and what Plumbing Code do you fall under? You are still discharging a major fixture past a unvented minor one but I don't think it will suck the trap seal out since it will be wet vented by the toilet vent. Let's see what the other experts think.
Regards, b Tom

Ahhh, I forgot to mention location. I am in Missouri. I would like to stay legal, however, this home will not be looked at by any inspectors after completion.

Hi Dluna...

If you want to stay legal... add the 1.5" vent to the shower drain and run that up to 48" off finish floor and connect into the 2" vent as you suggested you might do if needed. It is needed... ;)

MARK

But Mark, Will his present set up vent?

I think you said it well, Tom... major fixture draining past unvented minor fixture... usually a problem most of the time.

Now, if he connected the shower drain into the toilet vent, then he would be wet vented and all set.

What are you thinking here..?

Mark,
He's wet vented now. His wye's only 14 inches away from a vent on a 3" branch. He's wetvented by 14 inches of the 3" branch. So it's not legal but it will work, right? Cheers, Tom

It's not how we do it in my area Tom, but it should work... yeah. Dluna... how far away will the shower be from this connection?

Guys, if it helps, I can move the shower drain much closer to the vent. The layout of the bathroom actually goes toilet, shower, then vent up through the wall. I could easily start the drain with the toilet, then shower drain into that, then vent after that... but I didn't think I was supposed to have two drains together and the vent downstream.

I can make the distance from the shower drain to the WYE be around 9 inches or a little less... and the WYE could be the very next thing that comes after the TEE for the vent.

THANKS FOR THE QUICK RESPONSES!!

A little closer will not make a difference here. I'd leave it as you proposed it Dluna... ;)

MARK

You could also run new vent for shower and connect it with those toilet vents. It looks like all plumbing is close by. It could be done in no time. That way, all fixtures would have its own vent.

I mentioned that earlier Milo... ;)

I mentioned that earlier Milo...;)

Oooops... missed that one ! Sorry Mark, it just tells me we think the same way :-D

Thanks again for the help.

It sounds like wet venting the shower would "work" but the proper way would be to tie into the vent higher up on the toilet vents. Anyone have time to explain why the code is written this way? What are the problems one might encounter (other than possible code fines)? I'm just trying to picture what "could" happen in my head.

While I have your attention I have another quick question about the shower drain. I found 2 triplever drain kits at Lowe's, one made of 1.5" plastic and the other out of 1.5" PVC. I went with PVC but I don't quite understand why they don't sell these in 2". Also, if I run my trap with 1.5" and then expand my pipe to 2" after the trap until it connects with the 3" drain... will I actually be gaining anything? Won't the 1.5" tub drain into the 1.5" TEE that came in the kit be a bottleneck? I don't see how I could get more flow in the 2" pipe if I am constrained to a 1.5" drain at the start. Even using a 2" p-trap doesn't seem helpful to me except for allowing more solid waste like hair, etc before clogging.

I think that is all of my questions for a couple of days :)

Hey Dluna...

Showers do not use the triplever assembly you are talking about... only TUBS or tub/shower combination units... ;) A shower drain will have a 2" shower strainer installed...see images below (socket-weld type or NO-CALK type)...and you will install a 2" PTRAP directly under the shower and connect into the strainer.

In terms of the wet venting, I'll let Tom take that as my definitions are pretty specific to Massachusetts (Mass state plumbing code) and his will be more universal answer!



MARK

He's wet vented now. His wye's only 14 inches away from a vent on a 3" branch. He's wetvented by 14 inches of the 3" branch. So it's not legal but it will work, right? I said it and I'll stand by it. Ya got to realize, plumbing codes address the worst possible scenario. If that 3" line fills completely up with water it will suction the water seal right out of your showers trap. But that ain't about to happen. Drainage, at best, will only fill the bottom 1/4 or 1/3d of the pipe leaving the rest clear for air movement. And air movement in a drainage system= venting.
I rest my case!
On another note.
I have another quick question about the shower drain. I found 2 triplever drain kits at Lowe's, one made of 1.5" plastic and the other out of 1.5" PVC. We don't install stoppers on our shower drains. Why would you want one on yours? Regards, Tom

I wasn't as specific as I should have been in my first few posts. This "shower" that I am talking about is actually a shower/tub combo unit. I just call them showers because I haven't taken a bath in 20+ years :) That is where all of that crazy business about a triplever came into play. I am sure that was pretty confusing now that I think about it... "Why would he want to trip a shower base drain?" :)

Hopefully there are no major differences when I tell you it is a combo unit. I still don't see why they don't sell a 2" kit.

Hold the phone! What is it that you're installing? A bathtub? A custom built tile soaking tub with a shower? What? Let us in on it! Tom

It is what I call a shower/tub combo one piece unit that I bought from Lowe's. This is the only place we will have a tub, but also wanted a shower available at the same time. Thus the reason I needed to install one of those triplever kits. Here's a picture of the unit:

This is more for my overall education, but can someone help me understand the deal with the 1.5" triplever kits. I will be 1.5" from the drain to the TEE for the triplever, but I could then go to 2" from there for the trap and down to where it comes into my 3" toilet drain. I guess I don't know enough about water flow, but it seems to me that if I am 1.5" from the drain to the TEE for the triplever kit, won't I be constrained to the amount of water that can flow. Will converting to 2" for the rest of the tub drain actually gain me anything? Again, the price to step up to 2" from 1.5" is definitely negligible, I just wonder if I am on the right track with my thinking.

THANKS AGAIN!

This is more for my overall education, but can someone help me understand the deal with the 1.5" triplever kits. I will be 1.5" from the drain to the TEE for the triplever, but I could then go to 2" from there for the trap and down to where it comes into my 3" toilet drain. I guess I don't know enough about water flow, but it seems to me that if I am 1.5" from the drain to the TEE for the triplever kit, won't I be constrained to the amount of water that can flow. Will converting to 2" for the rest of the tub drain actually gain me anything? Again, the price to step up to 2" from 1.5" is definitely negligible, I just wonder if I am on the right track with my thinking.

THANKS AGAIN!

I don't know why it's 1 1/2" instead of 2" most likely be because the tub shoe's only 1 1/2 ".(see image). You'll have to contact the manufacture and ask.
The 1 1/2" set up never bothered any of the other installed tubs why's it bothering you?

I dunno why it's 1 1/2" instead of 2" most likely be because the tub shoe's only 1 1/2 ".(see image). You'll have to contact the manufacture and ask.
The 1 1/2" set up never bothered any of the other installed tubs why's it bothering you?

Your picture describes exactly what I am talking about. Everything you have pictured in my setup is 1.5" As I'm sure you know it joins at a TEE and then you can begin the p-trap etc. I wouldn't say it is bothering me...I just like to have a good understanding of what is going on so that I can use that knowledge later on. EVERYTHING I have read calls for a 2" drain on a shower and since this is all 1.5", it is just making me wonder. Again, I could go convert the 1.5" to 2" right away before the p-trap...but I am trying to understand if it would actually allow more flow this way than with simply keeping it 1.5" until it reaches the toilet drain. Perhaps it is a little bit of my OCD shinning through :)

Thanks again for your assistance.

Dluna11w: You have very good point: Why don't tubs have 2" drain ? I wondered that myself many times before. It could certainly drain water lot faster than though 1 1/2" drain. However, that's the standard that was established long time ago and is holding on up to today. Perhaps, one day manufacturers will change it to 2".

Yes, we convert from 1 1/2" to 2" right above the trap.

Now, that being said: in my area, you are required 2" trap and drain for tub. So here you have it...

My code also mandates a 2" trap. [QUOTE][ I am trying to understand if it would actually allow more flow this way than with simply keeping it 1.5" until it reaches the toilet drain/QUOTE] Certainly a 2" pipe will allow more volume to pass then a 1 1/2" one but you must realize that when draining under gravity that the [pipe never completely fills with water and It isn't 1 1/2" all the way to the toilet brnch. It's 2" from the trap. Regards, Tom

Very good point , Tom...