Double vanity rough-in question.

[burchis]

Would this arrangement of a vent-tee work in stead of double sanitary tee? I plan on wet-venting from about 5 feet away.

Thanks for any help and/or comments.

 

[Caduceus]

Wet venting isn't going to work in this situation. I also would recommend using a cross instead of the tee you have. Out of the top of the cross you can put a 90 ell coming out of the wall for a cleanout as long as it doesn't get blocked by drawers and is accessible. Better yet, if you can use a wye a bit lower on the vertical to go to one sink then a 90 on top of it to go to the other sink. Hope that makes sense.
As far as venting, the vent would have to be after the trap before you change from horizontal to vertical.
Is this a new construction house or a personal remodel project?

 

[havasu]

Cad, since I am also preparing to convert a single basin to a double basin, could you draw out what you are describing?

 

[Caduceus]

Havasu, I don't have the computer savvy to do that, but I am consulting my 'internet technical trainer', a.k.a The Wife, unless you can explain it.

 

[Caduceus]

I neglected to mention that if a cross is used, a vent must be installed above it and continuing through the roof or AAVs used at each fixture after the vanity is installed.

 

[burchis]

This is remodeling in 35 year old house. Basically I am just rearranging an old bathroom, where originally there wasn't any venting at all. I'm doing all the work myself and no county inspector will be involved.

Could you explain what problems I would have by using the vent-tee as shown in the photo? i.e- partial waste from one drain flowing into the other drain, etc.

Would a double-wye work as apposed to your suggestion of using a wye and 'L" combination?

 

[johnjh2o]

With that setup the traps on the sinks will siphon allowing sewer gas to enter the home. The other concern is when trying to snake the line from under either sink the snake would just run from one sink to the other without entering the common drain line. A double Y would make drain cleaning better but you still have the same problem with sewer gas. The correct way is with a double sanitary tee with a vent coming off the top. Just because there is no inspection doesn't make what your doing any less dangerous. Codes are written for a reason. Do yourself and your family a favor and do the job correctly.

John

 

[phishfood]

Echoing what the others have said, with a slight twist. I would use a single sanitary tee underneath another single sanitary tee, the second one being at the height that you currently have the drains at. Then, if necessary, use a slip extension to to attach the vanity bowl to the lower drain arm.

And make sure you vent the stack. The wet vent that you are trying to use is an S trap, disallowed by code for a reason.

 

[LiQuId]

THERE IS NO VENT IN YOUR PICTURE... this is bad, you must install a vent.

IF you want to use this type f configuration you must install a double sanitary T not the bull headed t that you have there and at VERY MINIMUM install an air admitance valve on the to of it, with an access door to get to it.

 

[burchis]

Can an AAV value be used on top of a double sanitary tee which would be closed off with drywall.

 

[johnjh2o]

No It must be accessible. But your on the right track. That can be done by putting in a access panel and covering it with a removable mirror.

John

 

[Caduceus]

A variety of AAV manufacturers will even show a digram on the box as to how you should install them underneath the vanity. One AAV per trap in your case.
Look at the opening picture of this PDF from Oatey: http://www.oatey.com/apps/catalog/instance_assets/assets/OAT_AAV_SVA_link3.pdf

 

[Mr_David]

You can try using an Island sink type of vent that is acceptable with out using a AAV
And a couple more related pictures.

Just a suggestion. You will have to make some modifications to get a double fixture fitting to to work

 

[burchis]

I read that there are two types of AAV's, one for a fixture and the other for system drain. So I am thinking about installing a system type AAV on top of a double sanitary tee to serve both vanities.

What is the purpose of having access to an AAV since manufactures state they last from 30-50 years.

Thanks for everyone keeping this post active.

 

[johnjh2o]

For one it's code. As far as lasting for 30-50 years no one can say that as they have not been around that long. Faucet manufactures say there faucets will last for life. We all now that's not true. We were also told that the U.S.A. would never loose it's AAA rating. Need I say more. AAV's will never be as good as a vent through the roof. They are mechanical and all things mechanical at some time will fail.

John

 

[burchis]

So can I assume the only reason to have an access to an 'air admittance value' is in case of having to replace it?

 

[phishfood]

If you install a vent ell on top of the double sanitary tee or even better, the double fixture fitting Mr. David showed, you can use another ell to turn back vertical once the cabinet is installed. Then install an AAV on top of that, and it will be accessible underneath the vanity.

 

[johnjh2o]

That is the main reason. But it sounds like you feel it's not reason enough for you. It's your home and your choice to follow code or not. What seals these things is a rubber disk that is held in place by a small spring. As I said before it will fail. Good luck with your project.

John

 

[burchis]

Thanks to all that have contributed to this post. Let me say that I am not wanting to circumvent code or do any work incorrect. I simply post my questions to learn the 'how and why' of things. I would not be on this forum if I intended to do things any old way. I wanted input from anyone that has already experienced what I am about to do. As I received replies, new thoughts and questions came to mind and I followed those thoughts. Again thanks to all and my apologies if I came across insincere.

 

[havasu]

No apologies are necessary. I believe the only dumb question is one that is not asked and we all learn in here!