Plumbing from one vanity sink to two

[Dillon]

Currently we have a one sink vanity and are wanting to do a two sink vanity. Please take a look at these drawing and tell me if either or both will work for the drain. The vent line currently goes straight down and connects to the drain from the sink. The current drain for the sink is out of the wall coming through the floor. The way I want to plumb it now is in the wall with the drains coming out through the wall. This is on a structural exterior wall with 2x6 construction. I believe that means it is ok for me to bore 2 inch holes without having to add extra support. The biggest difference between the two is that I will have to drill an extra hole in a stud for the top picture. That means one stud will have two 2 inch bore holes. The other option would just have one bore hole per stud. For the water lines I plan to just bring my hot an could up through the bottom plate and then tee off of them to have supply for each sink.

In this picture the two 90 elbows that are pointing up would actually be pointing into the the room for the sink to connect into.

In this picture the 90 elbow on the far left of the horisontal line would face into the room for the sink and the first Tee from right to left would point into the room for the other sink connection.

 

[Cacher_Chick]

The upper diagram is correct, using a 2" drain and 1-1/2" vent.

 

[Sponsor]

 

[hj]

There is no way you can orient the left hand tee in the bottom drawing so it would be a proper installation. There is NO "double fixture Y", so either you have the wrong fitting or the wrong name.

 

[Reach4]

You can call the fitting a 2 in. x 1-1/2 in. Double Sanitary Tee.

 

[Asktom]

The fitting you need is a 2 x 1 1/2 x 1 1/2 x 1 1/2 double fixture tee. If the drain below that fitting is 1 1/2", not 2", then there is no right way to do it. The closest you could do is use a 1 1/2" double san tee. But, if you ever had to run a snake down one lav it would come up the other lav, so, you would want a clean out on the vertical section. You could stack two 1 1/2" san tee, which would eliminate the snake crossing over problem, but then both the drain and wet vent would be undersized. Don't use a double wye because that could cause the traps to siphon.

 

[Cool Blue Harley]

You can call the fitting a 2 in. x 1-1/2 in. Double Sanitary Tee.

Grouping plumbing fixtures in certain areas of buildings can simplify the design of the plumbing system. In back-to-back and side-by-side installations, one drainage pipe serves two fixtures. The fixture fitting used is similar to the one used for single fixtures but with a dual opening. It is specially designed with more of an angle for the entry of flow into the barrel of the fitting. In this manner, the flow from one fixture cannot flow into the trap arm of the adjoining fixture. The proper term for this fitting is a "double fixture fitting." It also is sometimes referred to as a "Figure five fitting." This is due to the illustration number as it appears in the cast iron fitting catalog.

 

[Dillon]

My bad, I had the wrong name. I did mean a double sanitary tee. I will be using 2 inch for drain and 1 1/2 for everything else. Sounds like the top picture is the way to go.

 

[Reach4]

My bad, I had the wrong name. I did mean a double sanitary tee.

The others are right about the double fixture tee being the best fitting... I was going by what was available in PVC at Lowes and HD.

 

[Cacher_Chick]

My bad, I had the wrong name. I did mean a double sanitary tee. I will be using 2 inch for drain and 1 1/2 for everything else. Sounds like the top picture is the way to go.

No, a double sanitary tee is the wrong fitting. You need a double fixture fitting, which looks similar, but is not the same.

 

[Cool Blue Harley]

The others are right about the double fixture tee being the best fitting... I was going by what was available in PVC at Lowes and HD.

It is NOT a "Double Fixture Tee." It is a "Double Fixture Fitting" or a "Figure Five Fitting." Nomenclature is very important in plumbing. Please see my post above.

 

[Dillon]

Alright I must have the wrong thing. So I need a double fixture fitting and not the double sanitary tee. Correct?

 

[Cool Blue Harley]

Correct.