Size of sanitary tee needed ,please!

[Aggie83]

Howdy. I live 35 miles from a hardware store and need info that I'm sure is easy for this forum.

I am plumbing a bathroom in a large workshop building ( 40 x 80) that already has the rough-in plumbing under the concrete slab. So far, so good. I plan to drain a bathroom sink and a kitchen sink into the same vent, on opposite sides of the wall. the vent is 2 inches. Do I use a 2 x 2 x 1.5 x 1.5 double sanitary tee,, or a 2 x 2 x 2 x 2 double sanitary tee? Or does it matter?

I have not bought the adapter fitting..... but I think they are 1.5 inches. My memory (often faulty) tells be to use the sanitary tee with 1.5 fittings, then a short length of 1.5 pipe then the adapter? Avoid including a reducer?

thanking you in advance.

 

[Twowaxhack]

Personally I would use two sanitary tees.

The lavatory would be on top. 2x2x1.5” San tee. 1.5” trap or 1.25” trap. I use 1.5”.

Then below for the kitchen sink I’d have a 2” San tee. I use 2” ptraps for kitchen sinks.

Or you could use a cross, I typically don’t. 2x1.5” cross or a 2” cross with a reducer or two. Your choice.

 

[Aggie83]

Thank you!

A 2" p-trap for a kitchen sink sounds like it would drain better. This one will have low usage other than cleaning office coffee pot and cups. So, to do the 2" kitchen set up, you use an adapter with female threads to connect to the sink drain, then glue a 2" tailpiece?

On the double sanitary tee versus a cross, I'm not sure I understand why cross is better? (and I may be using incorrect term...)
cross


double sanitary tee

Karen

 

[Twowaxhack]

You have two types of fittings pictured.

The straight cross is used for pressure applications, not drainage. That’s the first picture.

The second pic is a Sanitary cross. It’s used for drainage.

When I used “ cross “ in my posts and we’re talking about drainage, I’m referring to a sanitary cross not a pressure application cross.

Personally I would use 2 sanitary tees. One on top of the other.

The top one for the lavatory 2x1.5” and the lower sanitary tee for the kitchen sink. 2” sanitary tee.

2” sch 40 ptrap with a reducer to 1.5” in the inlet for the k-sink.

 

[MicEd69]

I'm assuming that your kitchen sink does not have a garbage disposal and never will, correct? If it does have a garbage disposal, or if you think someone will put one in, I suggest you do what Twowaxhack said and use two sanitees. The top sanitee for the bathroom sink, and the bottom for the kitchen sink.

 

[Twowaxhack]

Or you could use a 2x1.5” sanitary cross with a couple 1.5” trap adapters.

The kitchen sink and the lavatory would use 1.5” traps.

Or you could use a 2x1.5” double fixture fitting instead of the 2x1.5” sanitary cross. I like the double fixture fitting better…….

 

[Twowaxhack]

Here’s a double fixture fitting.

Expensive. I’d stack San tees if possible.

https://www.supplyhouse.com/Spears-P500-251-2-x-2-x-1-1-2-x-1-1-2-PVC-DWV-Double-Fixture-Fitting

 

[Aggie83]

I'm assuming that your kitchen sink does not have a garbage disposal and never will, correct? If it does have a garbage disposal, or if you think someone will put one in, I suggest you do what Twowaxhack said and use two sanitees. The top sanitee for the bathroom sink, and the bottom for the kitchen sink.

Nope should never have a disposal on it! It's an office sink.
I may have a double fixture fitting in my "fitting box of leftover stuff"!

Many thanks to all.