another Single Vanity to Double Vanity thread, IPC

Users who are viewing this thread

Tekmassa

New Member
Messages
5
Reaction score
0
Points
0
Location
FL
I've read the previous posts regarding this conversion, and I'm hoping to get some expert advice on my specific problem. I'm converting my master bath single vanity to double vanity, and the new double vanity has drawers in the middle preventing me from using a common drain on a single p-trap (that would've been too easy). Please see the below photo of my current (less than impressive) plumbing:

originalPlumbing.jpg


The cutout section is between two studs, and the 2" drain is right up against a stud. The vent goes straight up the wall and to the roof from here. I have no idea what the 3/4" PVC duct-taped to the 2" drain pipe is for??

I'm looking at two potential ways to get where I need to be to have two drains for my two sinks.

Option #1 - 45 degree bends to allow use of double fixture sanitary tee
45degreebends.jpg


Option #2 - stacked sanitary tee
stackedTees.jpg


I will need to go through the stud on the right side with both the drain and supply lines for the second sink. My two questions:

#1 - What is the 3/4" PVC for? :confused: It comes out of the slab and goes straight up, but does not exit in the attic.

#2 - Which of my two options is the better choice? Are both bad?

Also, any additional concerns/considerations?

Your advice is greatly appreciated!
 

FloridaOrange

Plumbing Designer
Messages
1,298
Reaction score
2
Points
36
Location
SW Florida
Option 1 looks fine in my book.
I would guess the 3/4" PVC is for condensate, do you have an AHU above nearby?
 

Asktom

Member
Messages
745
Reaction score
32
Points
18
Location
Victor, MT
Option 1 - You are using a double san tee, it should be a double fixture tee. You won't find one with a 2" barrel and 1 1/2" branches, you would need to get a 2" and put bushings in the branches.

Option 2 - If you turn the elbow on the right out of the wall rather than going up and then out you will be fine (if not symmetrical), assuming the bottom of the trap will clear the cabinet. By going up and then out you take the vent out of play, which is not legal and creates a situation where the trap may siphon.
 

Tekmassa

New Member
Messages
5
Reaction score
0
Points
0
Location
FL
I would guess the 3/4" PVC is for condensate, do you have an AHU above nearby?

Nope, the AHU is on the complete opposite end of the house. The only thing I can think of is that our old water heater had the pressure relief valve tied into a pipe going into the wall that has since been capped. The water heater is on the other side of that wall approx 10 ft. down.
 

Tekmassa

New Member
Messages
5
Reaction score
0
Points
0
Location
FL
Option 1 - You are using a double san tee, it should be a double fixture tee. You won't find one with a 2" barrel and 1 1/2" branches, you would need to get a 2" and put bushings in the branches.

Option 2 - If you turn the elbow on the right out of the wall rather than going up and then out you will be fine (if not symmetrical), assuming the bottom of the trap will clear the cabinet. By going up and then out you take the vent out of play, which is not legal and creates a situation where the trap may siphon.

It sounds as if Option #2 may be the best bet, going straight out instead of up and out for #2. I will need to measure twice to make certain the opening in the back of the vanity will accommodate the outlets at both heights. I was unsure if stacking the two san tees as I had was acceptable or not.

Thanks!
 

Terry

The Plumbing Wizard
Staff member
Messages
29,946
Reaction score
3,460
Points
113
Location
Bothell, Washington
Website
terrylove.com
Option 2 is not legal.
Turning the drain upwards creates an S trap.
If you are considering wet venting one teel over the other, the vertical would need to be a 2" pipe.


In UPC plumbing, option 1 would need a double fixture fitting, not a sancross.
 

Tekmassa

New Member
Messages
5
Reaction score
0
Points
0
Location
FL
Option 2 is not legal.
Turning the drain upwards creates an S trap.
If you are considering wet venting one teel over the other, the vertical would need to be a 2" pipe.


In UPC plumbing, option 1 would need a double fixture fitting, not a sancross.

If I go with option #2 I'll be sure not to turn the drain upwards.

Regarding the double fixture fitting, would I be able to find this at my local big box retailer (Home Depot/Lowes)? Would it be labeled as a "double fixture fitting"?

Thanks everyone!
 

hj

Master Plumber
Messages
33,599
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
The drain does NOT have to directly behind the sink's opening, so you should be able to put the back to back fixture fitting in the vertical riser, and then offset back to the sink inside the cabinet.
 

Tekmassa

New Member
Messages
5
Reaction score
0
Points
0
Location
FL
Ok, I have two follow up questions. I cut out a larger section of drywall to do all the work today and made two interesting (to me, at least) discoveries.

First, the 3/4" PVC pipe I was puzzled by in my original post, seems to just end a few inches up. It's not capped, and I have no idea what it is for? From the lack of obvious stench, I don't believe it's connected to the drainage system. It's just sticking up from the slab right next to the 2" drain.

mysteryPVC.jpg


Secondly, the copper water supply lines (1/2") have a 12" long 3/4" extension, that go nowhere. They're capped and the only thing I can think of is that they were put there to allow them to be affixed to the studs for support? I plan on running the lines through the studs on the left and right, so they'll be supported by the studs. Anything I should be aware of before removing these 3/4" capped extensions?

extraPipe.jpg


Again, thank you all for your advice!
 

Terry

The Plumbing Wizard
Staff member
Messages
29,946
Reaction score
3,460
Points
113
Location
Bothell, Washington
Website
terrylove.com
The copper 3/4" pipes with caps are water hammer chambers meant to prevent water hammer.
They tend to fill up, so we use mechanical hammer arrestors now. But since this is for a lav, we don't normally install them there anymore.
It's for a "quick closing" valve.

The 3/4" PVC, it could be for a p-trap that needs priming, or it could just be extra.
Pretty strange.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks