Retrofit and Air Gap

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by wlam08, Aug 8, 2007.

  1. wlam08

    wlam08 New Member

    Messages:
    9
    I have a dishwasher hooked up to my disposal with a high loop under the sink. Every now and then, I get a sewer-type smell in the dishwasher. I was thinking of installing an air gap, but I have granite counter tops that I'd have to drill a hole through.

    Can the air gap somehow be installed inside the sink cabinet as an alternative?

    [​IMG]
    Last edited by a moderator: Sep 28, 2007
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,330
    Location:
    New England
    Don't know for sure, but if there is enough room on the rim of the sink, you might be able to install it there. If it is an undermount and there is no part of the sink, no. Drilling a hole in the granite isn't that bad.
  3. GrumpyPlumber

    GrumpyPlumber Licensed Grump

    Messages:
    1,404
    Location:
    Licensed Grump
    If you've never drilled granite...get a pro to do it.
    By definition an air gap means it should be above the flood rim of the fixture (max height the sink basin can fill), an air break is what it's called when below the rim.
    Your local plumbing code will specify if you need one or the other.
    Best bet is to look at local code, local codes often refer you to MFG specs for APPROVED MFG's, in other words...the local hardware store may carry air gap devices that aren't approved by local code...so reading the specs would be moot.
    The reason I'm stating this is that air gap requirements on dishwashers vary, depending on local code. (geesh...I think that made sense)
  4. sewer smell above the counter instead of in the dishwasher. Is that what you want? It could happen. A sewer odor coming out of the air gap so you can detect it more easily.

    i think the bigger question that needs asking is this. Why is a sewer odor present? Then, will adding an air gap solve the problem or make it worse?

    shortcircuiting the diagnosis, to say you want an air gap. What you really want is not to have any sewer smell ever.

    So.... what might be breaking the seal of the kitchen sink P trap?

    David
  5. got_nailed

    got_nailed DIY Senior Member

    Messages:
    277
    Off the wall thought.

    Why not put a second p trap under the sink and only run the dish washer into it.

    If there is slack in the dishwasher hose why not put a dip in the line to keep water in the line.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,330
    Location:
    New England
    Getting a diamond coring bit caught in a thick piece of anything can be a real eye-opener, so yes, you do need to be careful, and yes, getting someone to do it for you where they will warranty the situation is desirable. But, getting someone to do it after the slab's installation may be next to impossible since they won't want the liability. That leaves you to do it. The deeper the hole, the more chance for it binding. A jig to hold the drill plumb is a bonus here and a slow speed.
  7. Kilgore!!!!

    Kilgore!!!! New Member

    Messages:
    4
    The big problem here is siphoning backwards.
  8. got_nailed

    got_nailed DIY Senior Member

    Messages:
    277
    check valve?
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