Correcting S trap under kitchen sink

Discussion in 'Toilets and Sinks' started by Zanne, Aug 8, 2014.

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  1. Aug 8, 2014 #1

    Zanne

    Zanne

    Zanne

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    I posted about this before in my discussions of my garbage disposal installation, but I wanted a fresh thread in case stuff got missed.

    The old configuration was a mess (the garbage disposal did not drain well):
    [​IMG]

    Because it was already S-trapped and there was no available outlet through the wall for a vent (and I needed to get this fixed asap since the sink had been out of commission and dishes were piled up), I temporarily used this setup:
    [​IMG]

    I then started thinking of how to configure it so that I could get it vented properly (AAVs are NOT allowed in my state so that option was out). I came up with this crappy rough sketch.
    [​IMG]

    After looking up some parts I started to get a better idea of what I could do. I figured I could use a compression to PVC fitting to bridge it to a 1 1/2" sanitary tee that takes it down to 1 1/2" to 3" (or 2" if it turns out that is the pipe size under the house) wye to hook up to the existing pipe that has a cleanout and on top of the tee I would have an elbow to take the pipe out through the wall at an angle (so it would not be a flat vent) and another elbow to make it go up outside the exterior of the wall.
    [​IMG]
    (obviously that is not to scale)

    Then my next hurdle is the window above the sink. As you can see in this photo, the existing vent pipe routes around the window. I'm not sure if it is actually 6 inches above the flood level and this terminates under the soffit.
    [​IMG]

    So, once outside the house I would need to route it around without having it go flat/horizontal before the 6" mark. I'm thinking another elbow or something and trying to get it to start going sideways at an earlier point with another elbow. I'm just not sure how to measure for the angles and where all of the holes should be. I am not thrilled with drilling through the siding, but I don't want to tear up the backsplash above the sink. (I don't care about the look under the sink).

    Is the configuration in my last sketch OK? Should I make any changes?

    Any advice?

    (I know Chris mentioned Sika Flex as a sealant...)

    I admit that while I know the rules on the required slope, I am not exactly sure how to check the slope when I'm dealing with stuff that isn't square/level. Any tips on how to do that? Is there a set angle for particular slopes? (this sort of thing was not covered in my college math classes years ago).
     
  2. Aug 9, 2014 #2

    Matt30

    Matt30

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    Your horizontal offset looks back graded. Use a level to determine your slope.

    Also, I would of just used an air admittance valve instead of running the vent like that. I enjoy the smiley faces on the pipe though!
     
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  3. Aug 9, 2014 #3

    Zanne

    Zanne

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    Do you mean the horizontal offset on the vent pipe outside? Yeah, that thing was either put in wrong, or it got messed up by the people who did the siding. It terminates under the soffit.
    It comes out from under the house like this:
    [​IMG]

    And then terminates like this:
    [​IMG]

    On the opposite side of the house there is a vent that terminates like this:
    [​IMG]

    So the plumber did one of them right.

    At the time these vents were put in, it was after AAVs were banned in my state. I don't know what the venting looked like before, but my plumber told me that the tenants ripped out the existing vents-- and he was the one who did the plumbing on the house originally so he would have known.

    Heh. I idiot-labeled the pipe when I took everything apart while trying to locate a clog. I can't remember why I added a smiley face.

    Someone on another forum told me that I can't have my pipe run out of the house through the wall and meet up with the vent pipe at lower than 42" from the floor. I looked it up and found no such rule in my state's code and then someone else said something about needing to be 6" above the flood level of the fixture-- but I thought that was only for horizontal runs and I intend to make it a vertical run (albeit at an angle). Is there anything wrong with the angle of the vent pipe in my drawing? (I would eliminate the portion of the vent that goes down to the cleanout and maybe use another elbow to try to route around the window without having two 90s (but I would have to do some measurements to figure out if that could be accomplished). I do know that the horizontal run under the window is actually less than 6 inches above the top of the sink and my sink doesn't have any openings for overflow.
     
  4. Aug 9, 2014 #4

    Mr_David

    Mr_David

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    The proposed set up looks good. The offset under the window, just replace the 2 - 90's with 2- 45'. or just lower the 90 under the widow just a tad to give that horizontal section fall toward the drain.

    a vent connected to another vent requires the tie-in above the flood rim of that fixture so if that drain gets clogged the fluids can't foul the vent connector.

    The existing vent connection at the bottom does nothing for the water seal of the p-traps in the kitchen. Each fixture should have its own vent. If you add a santee to the kitchen (in red) you should Not need the existing vertical section going back down to the 3"

    tumblr.jpg
     
    Last edited: Aug 9, 2014
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  5. Aug 9, 2014 #5

    Zanne

    Zanne

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    By connecting to another vent, do you mean a vent that serves other fixtures?

    The kitchen sink is the only fixture tied in to this vent, but for whatever reason he had it come off of the part just before the cleanout under the house rather than put it through the wall and run it up. Now, I get that he couldn't cut open the interior wall up high and I guess he didn't want to poke holes in the wall to the exterior.

    Is the vent outside still considered a separate/different vent if it only serves that sink?

    I was planning to eliminate the section underneath the point where the pipe comes out of the wall. I was also trying to figure out if I would have the space to put some less than 90 bends on the exterior. I'll have to figure out some measurements on how to get it to go out.

    I know another alternative would be to eliminate the pipe going down through the bottom of the cabinet and just route to the exterior wall, but I don't think that is a good idea because it does get down below freezing sometimes. I know I could probably wrap the pipe, but there is probably less chance of freezing inside.

    I'll have to play around with some sketches after I take a nap.
     
  6. Aug 10, 2014 #6

    phishfood

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    If you are going to drill through the wall anyway, why not just use a santee on the exterior pipe and use the branch of that as the drain for the sink, doing away with the pipe coming through the floor?

    And then use 2 45 degree bends to offset to the side of the window instead of the 2 90 degree bends that are there now.
     
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  7. Aug 10, 2014 #7

    Zanne

    Zanne

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    LOL. I was actually thinking about eliminating that, but I'm worried about freezing in winter.
    Maybe that won't be an issue since the drain pipe shouldn't constantly be full?
     
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  8. Aug 10, 2014 #8

    phishfood

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    The trap is the only part of the drain that should hold water, so it shouldn't be an issue considering your location.
     
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  9. Aug 11, 2014 #9

    Zanne

    Zanne

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    Should I put it out through the wall with a tee that has a cleanout or just a regular sanitary tee?
    And are there any issues with the height if it ties in at that point, or was that only if it was tying in to a vent serving other fixtures?
     
  10. Aug 22, 2014 #10

    Mr_David

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    the vent can have 90's. and if you want come off the top of the santee inside, 90 out the wall, then 90 up. The vent is for gas release and air induction when water draining out. 90's make it a bit harder to clean if you put a clean out outside. the purpose of the vent is to protect the p-trap water seal from siphoning out and loosing the water seal, air induction while it is draining.
     
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  11. Aug 23, 2014 #11

    phishfood

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    90's below the rim of the sink doesn't meet IPC code. I know much of California is under a different code.
     
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  12. Aug 28, 2014 #12

    Zanne

    Zanne

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    Hmm... So, out the wall and attached to a sanitary tee then... Do they make a sanitary tee that goes from 1-1/2" from the side and going up but 2" going down?
     
  13. Aug 30, 2014 #13

    phishfood

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    Yes, a 2" x 1 1/2" x 1 1/2" sanitary tee. The first number notes the outlet, the second number the run inlet, and the third the branch inlet.
     
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  14. Aug 30, 2014 #14

    Zanne

    Zanne

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    Thanks, phishfood! I'll take a note to look for those dimensions next time I hit the hardware store. Then comes the fun of figuring out how to get the outside one at the proper angle so it goes next to the window without the 90 underneath.
     

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