Basement utility sink plumbing with washing machine stand pipe

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Deathtofishy, Dec 4, 2019.

  1. Deathtofishy

    Deathtofishy New Member

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    Hello,

    I've gathered a lot of info from this site, but this is the first time posting on here. I couldn't find a direct answer to my situation so I wanted to get some opinions.

    I am having a sewer line replaced in my basement, that is under the concrete floor. While it is being replaced I figured I would replace all the existing pipes from the utility sink and upstairs sink leading to it with ABS. I also wanted to add a standpipe for the washing machine instead of just having it drain into the sink as it currently does.

    I watched this video from this old house on youtube that seems to be very similar to my scenario (although I already have the sink). But I had a few questions.



    THIS VIDEO IS INCORRECT. NONE OF THIS WILL EVER PASS A PLUMBING INSPECTION

    1. They use a WYE fitting to add the sink and standpipe, it would seem like I could just put in a sanitary tee above the cleanout on the vent pipe to the right and it would be easier and still work correctly. The vent goes up into the first story of the house and tee's into the kitchen sink drain up there. So believe my venting situation is slightly different then in the video since there is no drain coming in from above it.

    2. The pipe being replaced in the ground is 3", and the current piping above is 1.5" is there any benefit for me to enlarge all the piping above to 2" (of course the vent and drain coming from the first floor would be attached with reducing couplings and remain 1.5")? I just assumed the larger pipe would be less likely to have blockages from the utility sink and washing machine.

    Thanks for any insight.
     

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    Last edited by a moderator: Dec 4, 2019
  2. WorthFlorida

    WorthFlorida When the wife won't let you get a Harley!

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  4. Terry

    Terry Administrator Staff Member

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    Looking at the pictures of the pipes in your home, the pipe on your left going up is the vent. The one on the right is a drain for the plumbing above.

    With the new 3" drain, you will add a 3x2 santee to pick up the washer and use your existing 1.5" vent.
    You will also want a 3" cleanout there.
    A washer standpipe is 2", not a 1.5" like in the video.

    A laundry tray requires a 2" waste line with 1.5" trap and vent.
    A washer requires a 2" trap and standpipe with a 1.5" vent.


    You can't wet vent either the sink or the washer. They each need a vent.

    The double wye in the video is the wrong fitting. That type of fitting will allow the traps to siphon.
    Siphoning is when the water is pulled from a trap, and yes it makes a gurgling sound. You don't want the trap to siphon dry, the water is there to block sewer gases from entering your home.

    This Old House, in this video it's clear that they have no idea about how plumbing works, or the proper use of fittings, or the correct sizing. The video is a total joke and should be removed.

    [​IMG]
     
    Last edited: Dec 4, 2019
  5. Deathtofishy

    Deathtofishy New Member

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    Thank you so much for the responses. Glad I asked this question, got a couple more. Added a photo for reference.



    Terry, following your photo for my setup.

    I would add two santee's (3" x 2") above the new drain pipe, one 2" pipe goes left to the sink and has the 1.5" vent, the other goes to the right to the washer stand pipe, and I would tee off the 1.5" vent above and into that line.

    Does the cleanout go above,or below these two santee's for the washer and sink (I don't see one in the photo)?

    Above all the santee's and cleanout will be 2" pipe and then I just use a rubber 1.5" to 2" coupling to reduce down into the existing drain from the floor above. (further down the road If I open the walls upstairs I can swap the remainder for 2")

    Thanks in advance.
     

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  6. Deathtofishy

    Deathtofishy New Member

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    Also, any specific reason for the utility sink santee to be above the washing machine one?
     
  7. Terry

    Terry Administrator Staff Member

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    You can use a double 3x2 santee there. I prefer to have the santee above that as it is more useful for cleaning the lines.
     
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  8. Deathtofishy

    Deathtofishy New Member

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    Had basement floor cut and replaced the bad line under it today. After work I got the rest of the plumbing in. Hoping this all looks correct, bit more of an undertaking then I originally thought. If it is good, hopefully it will help someone down the road if they find this post and are in a similar scenario.

    Haven't glued in the standpipe yet as I wasn't sure at the time how close it could be to the outlet or if there was a minimum height. From what I found online, as long as It's 30-48" from the floor and its P-trap 12"or less from the floor its good. There is no required distance from the outlet, just that it needs to be a GFCI.

    Going to opt for the shorter height unless there is something I'm not considering?
     

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  9. Reach4

    Reach4 Well-Known Member

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    Trap arm under the sink looks like a problem. It should slope downward after the trap at 1/4 inch per foot until its vent.

    From what I read, some inspectors will accept your santees on their backs for venting, and others want combos. I am not a plumber.

    A support for your standpipe is probably a good idea and may be required.
     
  10. Deathtofishy

    Deathtofishy New Member

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    Trap arm does have slope (probably camera angle that makes it seem more straight then it is), but I'll double check how much of a slope, as I just eyeballed it when installing.

    Combo was too big to fit on the side with the sink, and the sink is bolted into the ground. So I just did a santee on each side. However, just looking for proper operation, their isn't an inspector coming by to look at it. I'm assuming the point of the combo instead of the santee is that it is just easier to snake, shouldn't have any bearing on the operation?

    Definitely already thinking of putting a support for the stand pipe and one for the drain coming down from the first story.
     
  11. Reach4

    Reach4 Well-Known Member

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    How about this, keeping the slope from the trap falling properly as it goes.
    img_4.jpg

    Switching to a trap adapter at some point would make it easier to get things adjusted. Glued joints need more precision.
     
  12. Deathtofishy

    Deathtofishy New Member

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    Trap adapter is on there. (blocked by trap in picture), tailpiece coming down from sink wasn't long enough to do what you have pictured at the time. So I thought the two angle couplings lowering the line would be okay. I can provide a better picture of the setup under the sink later today.

    should be easy enough to change with a longer sink drain pipe if necessary.
     
    Last edited: Dec 11, 2019 at 3:51 AM
  13. Reach4

    Reach4 Well-Known Member

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  14. Deathtofishy

    Deathtofishy New Member

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    Here is a better picture hopefully. As you can see I have the two 45’s to lower the line to navigate around the sink legs and meet to the 3 x 2 dual santee.

    Tested everything and it seems to all work excellent. Of course that’s in comparison to the old 1.5 galvanized pipe and partially collapsed 3” drain line under the basement...

    If there is some issue with the 45’s, I’m assuming finding a longer sink drain tailpiece or extension and eliminating them all together would work/be the easiest change.
     

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    Last edited: Dec 11, 2019 at 3:51 AM
  15. Reach4

    Reach4 Well-Known Member

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    The 45s are OK if in the horizontal plane with the 2% (1/4 inch per foot) tilt.

    If it works, that is good. I think this might be officially an S trap and theoretically subject to being siphoned dry.

    You have no trap adapter except at the tailpiece. A hub trap adapter could be glued onto the cut horizontal pipe, and the trap, and the upstream part of the trap arm, would be slip (not glued). See #2 on https://terrylove.com/forums/index.php?threads/chrome-p-trap-question.66784/ You could also use chrome-plated brass as you have for your existing tailpiece extension. You may not need the 45s, because the trap may have enough swing.
     
    Last edited: Dec 11, 2019 at 7:32 AM
  16. Terry

    Terry Administrator Staff Member

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    The trap arm grades at 1/4" per foot. You can't use 45's to bring it higher because that lets the trap siphon out. Remove the 45's that turn upward.
     
  17. Deathtofishy

    Deathtofishy New Member

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    Hub adapter seems like a good idea, didn't know that existed/didn't see it when purchasing parts. That should give me the option to lower the P trap overall.

    As far as creating an S trap, I was concerned, and if it was ever inspected it might be scrutinized. But, I assumed since the bottom of the P-trap is lower than the 45's, and where the horizontal pipe connects to the dual 3 x 2 santee, it couldn't create a syphon to dry the p trap?

    Sounds like I was wrong on that though.
     
  18. Reach4

    Reach4 Well-Known Member

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    House buyer inspectors can miss stuff. But if you are looking, that kinda stands out.

    The key to avoiding a siphon is to let air in to break the siphon. So your pipes may prevent the air flow. In practice, a washing machine or other laundry tub usage usually ends with a low flow/dribbles. So that would tend to refill a siphoned trap that could have siphoned during the high flows that came earlier.
     
  19. Deathtofishy

    Deathtofishy New Member

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    Grabbed hub adapter and lowered P-trap to get rid of the 45’s. Also have it at the proper measured slope, instead of just eyeballing it.

    Thanks Terry and Reach4 for all the instruction and insight. Really appreciate it.
     

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    Last edited: Dec 12, 2019 at 6:12 AM
    Reach4 likes this.
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