Vent stack

[spudDude]

I'm remodeling and the bathtub and toilet is on the same drain line. They are on a slab, so trying not to cut slab.. I raised the tub on a platform 12" high. I can now pita trap in the tub and want to put a studer vent between the tub trap and the toilet. If the toilet flushes the studer will vent the toilet, but will it help the tub? Need some help..

 

[phishfood]

So there is an existing bathtub and toilet now?

If so, there already is a trap under the floor for the tub. Do not add another one on top of the existing.

What vents the bathroom now?

You haven't mentioned the lavatory sink, are you moving that?

 

[spudDude]

The tub sucks the water from the toilet.. The vent is 11/4 pipe and 5' away from both. So what I want to do is add a AAV and put a new trap to the tub. But can a 2" vent service both tub and toilet?? And I want to leave the 11/4" vent stack there also.. Is that ok to do??

 

[phishfood]

If there is already a trap for the tub, you shouldn't add another one.

Where are you wanting to add the vent in?

2" is more than sufficient to vent a bathroom group with. However, you are better off to tie the new vent back in to the existing vent. AAV's are a last resort option, in my opinion. A one way valve, and they are mechanical, so eventually they will fail.

Where is the bathroom sink, and are you moving that as well?

 

[spudDude]

The problem is the old vent is 5' away from the tub..and more then 8' from the toilet..when I ran the old shower it would suck the water from the toilet.. The vent stack is over eight feet away from the bathroom..so what I did was I tied the new bath sink into the washer drain on the same wall as sink.it about 3' away but that's a 2" stack.. The opposite wall is tub and toilet ..there's the kitchen sink on the backside of that wall. It's a 1 1/2" stack.. I don't think that's big enough to service tub, toilet, and kitchen sink..so I can put aav in the attic on a 2" stack.. But..the problem is the trap for the tub is under the slab.. I'm trying not to cut the slab but that would mean there would b 2 traps.. Any ideas for a easy way out?? Thanks for any info..