Need advice on finishing a kitchen drainage repair

[toolguy603]

I'm very grateful for the help I received when I asked here how to get a straight cut on a 2" ID copper pipe. Now I need more tips and help to completely get the kitchen drain functional again. This is the diagram of what I want to accomplish, but I'm not sure of the best way to connect the kitchen drain into the drainage. I will better explain what I mean with some photos.

Here are photos of what the plumbing looked like when the two copper pipes broke. For the kitchen sink, it had two separate ABS kitchen drains fed into a copper pipe setup in the basement ceiling which is below the kitchen sink as seen in these photos:



Here is a photo after I combined both kitchen drains into one drain:

When I'm done with under the kitchen sink, I expect it to look like this with the one clear out on the p-trap. This is dry-fitted going into the basement for right now as this may need to be changed.

In this photo, you can see where I made the straight cut to the copper 2" ID drain, the hole through the joist for the pipe to be fed through, and where the drain from the kitchen sink would be coming down through.

This is another photo with an uncut 1 1/2" PVC coming through from the kitchen sink into the basement ceiling. Once the PVC is cut, the elbow would be flush against the basement ceiling.

The hole through the joist is roughly 3" by 3" with a depth of 2", so it should accommodate a 1 1/2" PVC pipe

The issue that I am having right now with this is that I'm unsure about getting the piping going from underneath the kitchen sink and through the joist. I'm not sure if it makes sense to just recreate what was originally with copper and then just to cap two of the 3 openings because then I would get a "better" angle into the joist instead of making two 90" angles. I'm also not sure if the two 90" elbow setup will even clear through the joist.

I need some help and tips from people here who have more experience with plumbing then I do. Thanks a million!

 

[Reach4]

You should have a vent before the output of the trap turns down. I did not check if AAVs are allowed in NH.

The point of an AAV, or other vent, is to prevent the trap from siphoning out.

Regarding your use of a glued trap, slip joint traps are preferable for most. They make aligning stuff easier. If you have not yet glued that bend that goes down, maybe you can replace that with a sanitary tee (santee) with an AAV 4 inches above the top port.

 

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[toolguy603]

You should have a vent before the output of the trap turns down. I did not check if AAVs are allowed in NH.

The point of an AAV, or other vent, is to prevent the trap from siphoning out.

Regarding your use of a glued trap, slip joint traps are preferable for most. They make aligning stuff easier. If you have not yet glued that bend that goes down, maybe you can replace that with a sanitary tee (santee) with an AAV 4 inches above the top port.

I believe the AAV is here in this photo as it goes through the whole house to vent out the roof/attic.


I do have a slip joint going from the kitchen drain pipe into the p-trap. I chose a p-trap with a clean-out, which I had to cement a fitting to it for the kitchen drain pipe to slip joint to it. Can I use slip joints moving down from there into the floor? I'm all for making this easier to align stuff in the kitchen sink cabinet. Or is there a p-trap with a clean-out that has slip joints?

 

[Reach4]

I believe the AAV is here in this photo as it goes through the whole house to vent out the roof/attic.

You need to vent the trap arm before the waste turns down.

Or is there a p-trap with a clean-out that has slip joints?

A slip-joint trap comes apart, and is like the ultimate cleanout. I have not seen anybody say those little drain plugs at the bottom of a p-trap U are useful for clogs. See https://terrylove.com/forums/index.php?threads/opening-up-p-trap-cleanout-plug.59985/

 

[wwhitney]

1) As Reach4 says, change the street quarter bend on the outlet of the trap to a san-tee (will need to leave space for a couple inches of pipe between the two), with an AAV on the top of the san-tee, at least 4" above that very short trap arm. An AAV under the floor is useless for venting the sink.

2) For the underfloor horizontal run from your stub down to the existing 2" copper, rotate your LT90 where the the kitchen drain turns to horizontal in the joist bay so that it is pointed at a 45 degree angle towards the joist with a hole in it. Use a 45 to turn to perpendicular to the joist and lined up with the hole. On the other side of the hole, use a LT90 to turn and line up with the 2" copper. All of these horizontal runs must be sloped at least 1/4" per foot, so the location of the hole in the joist will determine the elevation you need for the outlet of the LT90 where the kitchen drain turns horizontal.

Use a Fernco Proflex 3001-22 or Mission Rubber CK-22 to connect the 2" plastic to the 2" copper--you'll need to use a 2x1-1/2 "reducer" somewhere within the new plastic run to transition to 2" plastic pipe. They don't seem to make a coupling to go directly from 1-1/2" plastic to 2" copper.

Cheers, Wayne

 

[toolguy603]

Thank you both for your responses. I did purchase a slip-joint p-trap and it's much easier to work and adjust. I believe AAV are allowed in New Hampshire, but I'm having trouble finding confirmation of this while web searching. Also, thank you @Reach4 for the p-trap cleanout plug thread and I see what you mean about them not being very useful to clear clogs.

@wwhitney please find my updated diagram with the 1-1/2" PVC 45 you suggested. I did spec a Fernco Proflex 3001-22 for between the copper and the new PVC. Then I work down to 1-1/2" PVC using the Wye in the diragram. I have to make new measurements for some of the PVC, but this appears better. Thank you for your suggestions.

 

[wwhitney]

@wwhitney please find my updated diagram with the 1-1/2" PVC 45 you suggested.

Surely you have the 2x2x1.5" wye reversed, the existing copper is downstream and the wye should be pointed towards it?

Cheers, Wayne

 

[toolguy603]

Surely you have the 2x2x1.5" wye reversed, the existing copper is downstream and the wye should be pointed towards it?

Cheers, Wayne

The diagram does not depict it well, but I am replacing the copper 2x2x1.5" wye with a PVC 2x2x1.5" wye.

 

[wwhitney]

The diagram does not depict it well, but I am replacing the copper 2x2x1.5" wye with a PVC 2x2x1.5" wye.

I understand that, but you have the branch of the wye pointed towards the cleanout, rather than towards the existing 2" copper pipe.

Cheers, Wayne