Sink rough in question

[Hcliffe]

I am installing a utility sink in my basement. The small horizontal pipe on the left is from the bathroom sink. The 2" vertical pipe goes up thru the floor and down into the concrete floor. I assume it is just a vent for the basement sink, not sure. I posted this "before" picture on another forum and they recommended I use a "double fixture" fitting, and not to use a "double sanitary" fitting as it would cause problems when snaking. I could not find one anywhere, so I used this "Y" fitting which I thought seemed like it would work the same as a "double fixture" fitting.

I finished the work and hooked it all up and it works great. Last night I showed the "after" picture to my friend who is a plumber contractor and he says I did it wrong. I should have used a "double sanitary" fitting because the way I did it, could cause the trap to siphon.

Please help!

 

[BMWpowere36m3]

should be a double fixture:

 

[Sponsor]

 

[Hcliffe]

Doesn't the piece I used work just like a double fixture?

 

[Reach4]

The double fixture fitting is designed to allow air from the vent into the horizontal pipes.

 

[Hcliffe]

Good to know, thanks for the quick reply. I guess I will re-do it.

 

[Reach4]

Don't take my post as approval of your plumbing. I am not a pro or even a good amateur on venting, but I happened to have picked up on that item.

The distance to that bathroom sink would probably play a part in whether things were OK to begin with, and the distance of the pipe or the presence of the angle could be a problem for the new sink. I don't know what those restrictions would be.

 

[Terry]

You are allowed 135 degrees on the trap arm, not 180
Add a vent on the trap arm and revent to the vent stack.
I assume that's a vent? and not waste from the next floor.

If you can hit the sink drain from the side you eliminate one 90
Going to the back wall is too much with the way you are running it.

The double wye is not correct for venting. It creates a siphoning S trap.
A double fixture fitting is correct, assuming you are only going 135 degrees on the trap arms.
Sometimes you are better off using a santee before the other lav, and running to the second location, and then tying back the vent again at 42"

 

[hj]

A double combination Y-1/8 bend would be preferable to what you used even though it is still not a proper fitting for back to back installations, nor is a sanitary cross. In other words the ONLY correct fitting IS a back to back fixture fitting.

Double fixture cross

 

[Hcliffe]

Thanks for the input everyone. I will re-do this with the double fixture fitting.

Terry, I'm not sure what you are referring to with the 135 and 180 degrees. Are you talking about the PVC I ran from the vertical pipe vent to wear the sink drain will be? Are you saying there are too many turns in it?

 

[Terry]

you are allowed one 90 and one 45 which equals 135. you have two 90's which equals 180. that is too much change of direction for a trap arm. you can't just keep putting horizontal 90's in position.

 

[Hcliffe]

Thanks Terry I follow now.

 

[krik]

you are allowed one 90 and one 45 which equals 135. you have two 90's which equals 180. that is too much change of direction for a trap arm. you can't just keep putting horizontal 90's in position.

Terry - two questions: is the _current_ setup only 180 because the fitting into the double wye is technically vertical? if this is replaced in its current layout with the double sani tee, it would become 240, but then even if you eliminate on of the 90s and hit the side wall with the trap arm you'd still be at 180, unless I'm missing something? I (and the original poster, I assume) am curious how you could do this without an additional vent in the side wall.

 

[Terry]

Counting from the end, one 90, two 90, then the third one that turns down at a 45 angle.
So remove the wrong fitting there, install the proper fixture cross, and now you have three horiztontal 90 degree changes. Now you are at 270 degrees.
Sorry I forgot about the double wye that was being replaced with the proper fitting.

So to answer the question, that all has to go.

There are ways to do that correctly, but the picture isn't one of them.

 

[Hcliffe]

So I really can't just go into the side of the sink because that would still be 2 90's for a total of 180. I guess I'm not sure how to run the trap if I put the sink where I want it.

 

[Reach4]

I suggest you post a top view sketch of the nearby walls, the vertical pipe and the laundry sink.

If your sketch was like this, could you maybe follow the orange path rather than the purple?

 

[Terry]

It's more a matter of installing vents in the correct location. You need to add vents on horizontal portion of the trap arm closer to the p-trap, and then tie those vents back in at 42" above the floor.

What you have shown, with the wye fitting will suck your trap dry, which believe it or not, is not what you are going for. The purpose of the trap is so that you can smell your wife's perfume, not the septic tank out in the yard. The water we want left in the trap blocks those smells.

I was helping in the kitchen for a woman whose kitchen had nice new granite tops and a deep stainless sink. The odor coming from the sink was horrible. I opened the cabinet doors and peeked in. The handyman had installed the disposer without a p-trap.
I cut into the wall, lowered the santee in the wall, and added a p-trap. The bad smell was now gone.

It's up to you what you want your bathroom to smell like.

 

[Hcliffe]

I appreciate everyone's input. The diagram that "Reach4" made is exactly my situation. I will eliminate the wye fitting and replace it with the double fixture fitting. Will that fix the siphoning trap problem? Or do I also have to fix the "too many turns in the trap arm" problem to eliminate the chance of a dry trap? Its not clear to me if the "too many turns" is a siphoning issue or an issue in case their is a clog in the drain etc.

 

[Divan10]

You are allowed 135 degrees on the trap arm, not 180
Add a vent on the trap arm and revent to the vent stack.
I assume that's a vent? and not waste from the next floor.

If you can hit the sink drain from the side you eliminate one 90
Going to the back wall is too much with the way you are running it.

The double wye is not correct for venting. It creates a siphoning S trap.
A double fixture fitting is correct, assuming you are only going 135 degrees on the trap arms.
Sometimes you are better off using a santee before the other lav, and running to the second location, and then tying back the vent again at 42"

Hi..in which part of the plumbing code book can find this rule of the 135 degress on the trap arm ???? Thank you

 

[Terry]

All this fuss about a double fixture fitting when the trap arm has too many bends on the right side for that to work anyway.
The lav on the right could have been run separate, and then the vent brought back at 42" from the floor.

The second lav could have been roughed around the corner. Not like this but something where the lower part is brought closer so that the trap with arm can have less bends.