When the tub drains, it will siphon the trap on the washer.
The washer needs either a vent connecting above the tee for the tub, or an AAV to break the siphon.
Hi, I'd like to double check how my venting is for two fixtures. Please see the attached diagram for how I planned on the draining/venting of these two units. I was mainly wondering if I can use the 2" stack for these units as the vent, or if i have to have an additional vent before the p-trap enters the 2" stack? These are the only 2 fixtures on this branch. They connect to a 4" in the basement which also has 2 bathrooms coming into it as well (they have their own venting)
You can not waste stack vent a washer.
What's your location? IPC requires a 3" up to the washing machine for new construction.
Semi-professional plumbing designer
Enjoying life in SW Florida
Regardless, the drain pipe from the upstairs cannot be used as a vent for the downstairs washing machine. And an AAV would only take care of half the problem with doing it.
Ok, so here's what I derived from the responses. This would be correct then?
Another question, for the vents coming off of the p-traps, do I use a sanitary tee, a wye with a 45, or just a regular tee? And where the p-trap connects into the stack, I was planning on using a sanitary tee, if that was correct as well.
Last edited by NickM; 06-11-2009 at 07:19 AM.
The code reads that the connection between the two vents has to be 36" OR 6" above the highest fixture whichever is HIGHEST. This is to prevent problems in case someone decides to connect a 36" high kitchen sink to the system some day. A Y with a 45 pointing downward will give the closese separation, the tee is the proper fitting for the connection to the drain, but since it wll have its own vent you are not limited to the tee, but can use any connection that works for you. You could use another Y with a 45 faced upright, then a tee in the vertical line which would place the vent as close to the drain as possible an it would be aligned with the upstairs vent so you would have a straight pipe between them.
Last edited by Terry; 06-02-2010 at 02:50 PM.