Please critique my Island Sink plan

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by JuanSigned, Apr 19, 2015.

  1. JuanSigned

    JuanSigned Member

    Joined:
    Jul 27, 2007
    Location:
    Utah
    I'm doing a complete remodel of my kitchen. Part of that has a new island for the kitchen sink and dishwasher. I've googled loop vents and Air Admittance Valves (AAV) till I think I understand how they work. I like the idea of a loop vent because there's nothing to go wrong and it's silent in operation, but the venting in my unfinished basement leaves me with a question. There are 2 drains vent connected to the horizontal run of the existing the dry vent before it goes vertical to the roof. Is the drain/venting plan I've drawn in green and blue in the picture OK?

    loopVentDrain.jpg
     
  2. hj

    hj Moderator & Master Plumber Staff Member

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    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    The green vent CANNOT connect to the "dry vent" until AFTER it rises 42" above the floor.
     
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  4. JuanSigned

    JuanSigned Member

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    Jul 27, 2007
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    Thanks HJ. There is another option for a vent that would meet that requirement, but it would be even more effort and cost. My local code allows for AAV's so given a choice between a loop vent and an AAV what would you do in your house?
     
  5. hj

    hj Moderator & Master Plumber Staff Member

    Joined:
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    Occupation:
    Plumber
    Location:
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    loop vent.
     
  6. JuanSigned

    JuanSigned Member

    Joined:
    Jul 27, 2007
    Location:
    Utah
    OK, lets try plans B and C

    Drain Plan B.jpg

    Plans B and C tie into a vent that used to serve the old kitchen sink. That 2" vent runs vertically to the attic where it connects to other vents and goes through the roof. It is further away but still accessible.

    Plan B removes the dry vent used in the first plan and the footer connection to the island drain. That's the only way I can see to keep the loop vent always slopping towards a drain. Plan B also vents the left drain which I'm guessing is going to be an issue. (even though the left and right drains joint under the slab just about where I'm standing in this picture)

    Drain plan C.jpg

    Plan C is the most work, but it looks the closest to the drawings I've seen on the Internet. There is still that pesky business about the loop vent having to always slop towards a drain, so the loop vent connection has to be lower on the stack.

    Is either plan OK?
     
  7. JuanSigned

    JuanSigned Member

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    Jul 27, 2007
    Location:
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  8. Reach4

    Reach4 Well-Known Member

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    Location:
    IL
    I am not a plumber, but I am wondering if you should add cleanouts.
     
  9. JuanSigned

    JuanSigned Member

    Joined:
    Jul 27, 2007
    Location:
    Utah
    Cleanouts are in the plan, but above the floor. Two are going in the sink cabinet one for the drain and one for the vent, and one is going in the vertical section of the vent pipe. When all is said and done I will be able to get a snake through the whole system. At some point I'm going to finish the basement and all of what you see in the pictures will be behind drywall.
     
  10. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    It seems to me that I read a cleanout is needed every time you go more than 135 degrees of fittings. Maybe I am mistaken. It looks to me as if you have 270 in the blue line from upstairs if your turns are all 90 degrees.

    I don't know if there is a requirement for vent cleanouts.
     
  11. JuanSigned

    JuanSigned Member

    Joined:
    Jul 27, 2007
    Location:
    Utah
    Maybe a line drawing will be easier to understand. This is roughly plan C. The difference between this and the idealized drawings I've found on the internet is where the loop vent ties into the drain. I think this will work, right?
    drain schematic.jpg
     
  12. JuanSigned

    JuanSigned Member

    Joined:
    Jul 27, 2007
    Location:
    Utah
    Bumping this back up to the top. I've googled till my fingers bled and found nothing about loop vents other than the "idealized, perfect world drawings" I'm considering going with an AAV because I know I can install that correctly. Please, before I install a device that some think is an item straight from Hades, look at my ideas. My local jurisdiction follows the 2012 International Plumbing Code and allows AAV's. I want to do this job to code, not so much because I care about the code, but because doing so typically means its going to work as intended. (and I like the idea of a loop vent because there is no chance of sewer gas coming into the kitchen.)

    Here's an improved schematic of what I'm thinking.

    drain schematic.jpg
     
  13. JuanSigned

    JuanSigned Member

    Joined:
    Jul 27, 2007
    Location:
    Utah
    It's done. I find these forums really helpful and I like to see it when others finish their projects, here's mine. After talking with a couple of local contractors and plumbers I went with an AAV in the end. Their consensus was don't be a fool about it, put in an AAV and be done with it. Getting the AAV to the require 4" above the trap arm also made a perfect place to put in a clean out. There's a little more slope than I'd like between the garbage disposal and the drain. The cool drain that came with the sink forces that connection down. If it becomes a problem I'll figure something else out.

    Img_3268.jpg Img_3267.jpg Img_3270.jpg
     
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