Attaching an ABS P-trap to an ABS Wye Horizontally or Vertically

[Victor Kernes]

Can you attach the outlet of a 3" ABS P-trap to a 3" ABS Wye if the Wye is in a horizontal position, laying on it's side? If not, then could you place the Wye vertically and attach a 3" Street 45 to the wye and then attach a Street 90 to the Street 45 and then the 90 to the outlet of the P-trap?

 

[wwhitney]

What are you trying to do? What is the trap for? What else is coming in on the wye?

Cheers, Wayne

 

[Sponsor]

 

[Breplum]

You can, if following all the rules for horizontal wet venting, use the horizontal configuration, if your jurisdiction allows it.
Standard style plumbing (prior to adoption of horiz. wet venting) dictates that every trap be individually vented where the vent basically rises vertically. In the case of a 2" trap, the vent is 1.5"

 

[Victor Kernes]

What are you trying to do? What is the trap for? What else is coming in on the wye?

Cheers, Wayne

Hello Wayne. We are installing three (3) Commercial 60# Wahsing Machines. So, there will be 3 P-traps and each trap will be vented and then attached to a main 4" lateral.
Victor

 

[Reach4]

Hello Wayne. We are installing three (3) Commercial 60# Wahsing Machines. So, there will be 3 P-traps and each trap will be vented and then attached to a main 4" lateral.
Victor

That sounds good. Your mock-ups don't show that. Venting needs to be done after the 2-inch trap U/J bend before the flow turns down. There must be at least 4 inches (2x nominal trap size) after the U and before the vent.Venting under UPC is supposed to be via wye or "combo" (combination wye and 45).

 

[Victor Kernes]

Can you attach the outlet of a 3" ABS P-trap to a 3" ABS Wye if the Wye is in a horizontal position, laying on it's side? If not, then could you place the Wye vertically and attach a 3" Street 45 to the wye and then attach a Street 90 to the Street 45 and then the 90 to the outlet of the P-trap?

That sounds good. Your mock-ups don't show that. Venting needs to be done after the 2-inch trap U/J bend before the flow turns down. There must be at least 4 inches (2x nominal trap size) after the U and before the vent.Venting under UPC is supposed to be via wye or "combo" (combination wye and 45).

I made a mistake in my last response. I was going to attach the vents downstream of each Wye and between each of the succeeding wyes. I was going to Plumb the P-traps directly into each wye. This is what shows on the mockup picture. So, you're saying that if I use the "Horizontal Wye" connection that the vent connection must be between the trap and the wye?

 

[wwhitney]

The dry vent connection for a trap always comes before that fixture drain joins any other drain.

Since you are using 3" traps, your vent connection can be anywhere from 9" to 72" after the trap weir, and the fixture drain can fall at most 3" (but at least 1/4" per foot) before the vent connection.

Then once you vent each trap, the fixture drain can join your 4" main with a wye. Either a horizontal wye or upright wye would be allowed. I'm a little unclear on whether there could be a sudsing issue that would make one of the two options better.

Cheers, Wayne

 

[Victor Kernes]

The dry vent connection for a trap always comes before that fixture drain joins any other drain.

Since you are using 3" traps, your vent connection can be anywhere from 9" to 72" after the trap weir, and the fixture drain can fall at most 3" (but at least 1/4" per foot) before the vent connection.

Then once you vent each trap, the fixture drain can join your 4" main with a wye. Either a horizontal wye or upright wye would be allowed. I'm a little unclear on whether there could be a sudsing issue that would make one of the two options better.

Cheers, Wayne

Thanks again Wayne. So, my mockup picture showing the Wye vertically with a Street 45 attached to the inlet branch, if I put the vent between the trap and the 45 connection, do you feel this is a better and less problematic design? And, would a Sanitary Tee be allowed instead of a Wye?

 

[wwhitney]

With the wye (inlet) "vertical" the vent connection needs to go between the trap and the 45. As to whether that's better than the wye horizontal, I don't have an opinion or the experience to speculate. Perhaps someone else can comment.

As to a sanitary tee on its back, definitely not.

Cheers, Wayne

 

[Victor Kernes]

With the wye (inlet) "vertical" the vent connection needs to go between the trap and the 45. As to whether that's better than the wye horizontal, I don't have an opinion or the experience to speculate. Perhaps someone else can comment.

As to a sanitary tee on its back, definitely not.

Cheers, Wayne

Thank you again Wayne. I know this takes a lot of time to respond to these posts and your time is appreciated.

 

[Reach4]

I wonder if circuit venting could be used for this under UPC. It's not bathroom stuff. I don't know if circuit venting is limited to bathroom stuff.

 

[Victor Kernes]

With the wye (inlet) "vertical" the vent connection needs to go between the trap and the 45. As to whether that's better than the wye horizontal, I don't have an opinion or the experience to speculate. Perhaps someone else can comment.

As to a sanitary tee on its back, definitely not.

Cheers, Wayne

Good evening Wayne. Victor here again. Can you view the picture I just uploaded with a new mockup of parts and the vent on the outlet of the trap to see is that is acceptable? Thanks

 

[wwhitney]

As I mentioned, the vent takeoff can not be a san-tee on its back (under the UPC), it needs to be an upright wye or a combo.

Those fittings have a longer run, so if you need to have the trap so close to the 4" line, you could turn the outlet elbow 45 degree towards downstream, and then use a 60 degree fitting to connect to the upright wye on the 4" line.

Cheers, Wayne

 

[Jeff H Young]

Three 60 pound washers commercial? Might try consulting the manufacture? Never seen plumbing like you're showing ? This is getting permits and inspection ?

 

[Victor Kernes]

Three 60 pound washers commercial? Might try consulting the manufacture? Never seen plumbing like you're showing ? This is getting permits and inspection ?

Yes, permits have been pulled and getting inspected when finished. This is why I'm trying to get this right the first time around. Victor

 

[wwhitney]

never seen plumbing like you're showing

One subtlety in several of the pictures is that there are some fittings that aren't dry-fitted to the assembly and are just there as props to hold things up. We're supposed to ignore those fittings. : - ) But yes, it seems odd that the washer drainage is coming into the trap on the horizontal rather than the vertical (like a regular standpipe).

The basic question is that if you're connecting a 3" drain line from a commercial washer to a 4" horizontal branch, is there an advantage to elevating the trap arm somewhat above the branch and entering it with an upright wye, versus having the trap arm in the same plane as the branch and entering it via a horizontal wye. Any thoughts on that?

Cheers, Wayne

 

[Jeff H Young]

Looks pretty weird Victor but I guess a 3 inch vertical coming up beside each washer with a santee at proper height and p trap continue up with vent . I've never done a commercial washer this isn't a laundromat? but some sort of uniform or big diaper service company?
no drawings or nothing eh?

 

[Jeff H Young]

Those don't look like 3 inch ptraps either and 4 inch mains whole thing nothing looks right

 

[Victor Kernes]

One subtlety in several of the pictures is that there are some fittings that aren't dry-fitted to the assembly and are just there as props to hold things up. We're supposed to ignore those fittings. : - ) But yes, it seems odd that the washer drainage is coming into the trap on the horizontal rather than the vertical (like a regular standpipe).

The basic question is that if you're connecting a 3" drain line from a commercial washer to a 4" horizontal branch, is there an advantage to elevating the trap arm somewhat above the branch and entering it with an upright wye, versus having the trap arm in the same plane as the branch and entering it via a horizontal wye. Any thoughts on that?

Cheers, Wayne

Okay, didn't want to bore you to death but I need to reveal the entire scheme. These are commercial Washing Machines. They have a 3" waste outlet connection. To the centerline of the waste outlet on the machines is 4.9" from grade (not much to work with). The washers will be mounted on a 6" pedestal raising the waste outlet center height to 10.9" above grade (still not much height). There are no existing drains inside the building. The client does not want the concrete floor cut open to install drains below the concrete because it is pre-tensioned concrete. So, I am trying to build a drain assembly above grade and behind all three washers with only 10.9 inches of height to center, then cut a hole at the very base of the inside wall just above the 2" x 4" framed footer that sits on the concrete base, and then attach our 4" assembly to the outside 4" sewer lateral existing in their garden area on the outside perimeter wall of the building. The architect/mechanical engineer is calling for vents on each trap, and they want us to take the 3" line of the machines and connect immediately into a 4" line as the main lateral which obviously is a bigger o.d. and eats up our height tolerance.
I have another brainstorm idea: can I take a "Street Sanitary Tee" and attach that to the outlet of the P-trap on a 45 degree angle and take the spigot or fitted end on the san-tee into the 45 degree connection of the 4" x 3" wye that is on the horizontal run? I could then take a 3" 45 and attach that to the san-tee that is on a 45 angle to get the upright position for the vent line to be attached vertically. Would the Sanitary Tee be ok on the outlet of the P-trap and then on a 45 degree angle? Victor

 

[wwhitney]

You can vent your trap arm by hitting the side entry of a san-tee, where the barrel isn't straight up and down, but is rotated 45 degrees.

Residential washing machines pump their discharge up, these machines have a 3" horizontal discharge with no pumping to raise the discharge?

Cheers, Wayne