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tumbulu

dishwasher install with drain below floor - no air gap?

tumbulu
15 years ago

Hi - my DW was re-installed to a new location that is not adjacent to the sink. since that time it has not operated properly. Had a service call from appliance store - the repairman indicated the drain needs to be 20" above base of DW. I looked at the install manual when I found it, and it does indicate that the drain below the floor is ok if there is an airgap. I suspect I am missing the airgap.

what is happening is that when the water gets into the dw, it apparently just drains out due to gravity. the appliance guy said he thinks i need the drain hose to loop next to the dw and empty into a standpipe that is 20" above floor level.

Is it possible that I don't need the pipe to come up thru the floor? just install an air gap? what is an air gap in this type of installation? if I have that air gap, can i do without the high loop? I will be calling my contracter back to address this, but am wondering it the plumber forgot the air gap/ high loop, or if the air gap was there and not functioning? thanks for any advice

Comments (7)

  • frodo_2009
    15 years ago
    last modified: 9 years ago

    yes you have to loop the drain up to the bottom of the cabinet.then down into a stand pipe the stand pipe is the pipethat comes off the top of a p-trap
    what is the hose hooked into now?
    you said it was a plumbing co that did this? un damn belivable....go to the supply store,,,never mind tell the darn plumber to hook it up right
    did you pay him yet?

  • live_wire_oak
    15 years ago
    last modified: 9 years ago

    Any comments from the professionals on the original post in Appliances? I think my post is accurate, both from a UPC and IRC standpoint, but of course, I'm not a plumber. :) I'm just a KD who has to deal with plumbing issues on a fairly regular basis and tries not to be too dumb about things. ;)

    Here is a link that might be useful: Post in Appliances

  • frodo_2009
    15 years ago
    last modified: 9 years ago

    tumbulu...heres the long and short of it
    its required for a drain line to be run to the dishwasher
    that includes a vent and a p-trap. the trap can be installed in the cabinet box beside the dishwasher
    it would require a stand pipe no longer than 24"
    the hose on the dishwasher does need to loop up to the top of the cabinet..now here you have the choice of 2 options
    you can either install a airgap fitting on the top of the counter,and the hose would be plumbed to the air gap then drop into the stand pipe
    #2 is to stop the drain hose 1" from the top of the stand pipe, strap it off so it does not move [air gap]
    #3 is the air gap fitting and then into the garbage disposal
    you don't have one there..

  • jake2007
    15 years ago
    last modified: 9 years ago

    This installation was done by someone who clearly didn't know the first thing about installing a dishwasher. If you paid for it, you should demand a refund. I wouldn't want that person back in my house fixing it.

    That said, Frodo outlined the proper way to connect the drain. The only issue I'm not clear on is the requirement for the air gap if you connect to a garbage disposal (I do know that you have to loop the drain hose up in that situation). Nevertheless, that's not your setup anyway.

  • davidro1
    15 years ago
    last modified: 9 years ago

    Yes, frodo here above, and live_wire_oak in the other thread (linked to above) got it right. -- 99.9% right.

    I'll add a bit of context, based on my knowledge of DWV plumbing. I am happy to share and to read feedback, and I don't mind plumbers telling me more..

    An indirect connection (before _Any_ P trap, not just the sink's P trap) lets air in or out, preventing the draining water from sucking open either the P trap or the DW's base (its "sump") which is supposed to have some standing water left in it. ((Note that doing the opposite would have the same effect as two P traps in series which is disallowed)).

    An indirect connection is a set up that lets the drain gurgle: it mixes with room air. It can look like a standpipe (that looks like your clothes washing machine's standpipe) or it can look like some other set up that looks_different but does the_same thing. This is why your DW makes gurgling noises in the kitchen drain pipe when it drains: it is pumping water into the drain prior to the P trap, so you hear it. It is not allowed to connect the DW drain to your plumbing behind a P trap, it must be in front of a P trap.

    You Are allowed to send the DW drain hose from an Air Gap directly to the kitchen drain without going through the garbage disposal first. The option to route through a disposer is one optional route. It is one option out of a very limited number of options.

    A "High Loop" brings the DW drain hose to the house plumbing before the sink P trap also, and in the sink drain is where the gurgling / air-mixing takes place, and that is where you will hear it. A dishwasher _Wye or _Tee is the connection part usually used but any Wye will do.

    A third option is if you install a separate stand pipe like a laundry standpipe: then that means a separate P trap which then presents other (minor) challenges, since it has to be connected with the right venting behind the P trap; this is venting for sewer gases (not room air venting) which is the usual meaning of venting when plumbers talk to plumbers.

    When a P trap is under the floor, the drop may be too far and the P trap may self-siphon because the fast moving (falling) water will all slide out. That is inertia because of the fall. However, it is not disallowed, it just calls for a professional plumber or a highly knowledgeable homeowner. (So yes, sometimes a P trap in a basement for a fixture on the first floor can be good; e.g. if it is right under the floor, up against the basement ceiling, and with the right venting too!)

    As live_wire_oak said in the other thread, this is all part of the plumbing code for health and safety reasons.

    Sewer gases cannot be allowed to enter a house, so P traps which could siphon themselves out are disallowed, and this is all an exercise in 3-D geometry including the drain diameter. Plumbers spend Years learning this and writing exams, so don't let a plumbing apprentice design your DWV plumbing, and double-check everything even if you think your plumber has all the answers, as they do make mistakes too. I have seen this more than once. The 3D thinking involved is complex, even for a new building where everything is built as a system all at once, but even more-so for a reno or remodel where the "system" is not all visible and sometimes not even fully understood.

    Above I mentioned that you would hear the DW drain gurgling. If one built a standpipe that got its air from up high in the dropped ceiling, the gurgling noise would be minimized. It would be a tall pipe with a Wye in it to receive the DW hose.

    HTH
    -david

  • frodo_2009
    15 years ago
    last modified: 9 years ago

    no david...let me explain a indirect drain
    a indirect drain is any drain that does not connect to the plumbing system directly, but uses an air gap
    an air gap..is a 1" seperation..from the the drain of a fixture. to the flood rim of an approved inlet
    such as a floor sink,floor drain or a stand pipe

    now that was code speak. let me break it down in laymen terms
    the drain from the dishwasher, cannot hook up directly to the plumbing system because...if the system backed up
    the sewage would back up into the equipment[dishwasher]
    so..it is connected by an air gap..which is
    a seperationm of 1"..so that if the system backs up
    it will not back up into the equipment[dishwasher]
    but will overflow on to the floor..thus.not contaminating the equipment[dishwasher]
    there is nothing in the code about gurgling or whatever that was all about
    the code is about health and safety
    the dishwasher air gap fitting
    is a fitting designed to give you this seperation
    that is why, after installing it.you can hook the hose up to a garbage disposal,
    altho...i personally disagree with the use of the air gap fitting. because i believe the air gap is achieved inside the disposal..but that is my thinking and is not code
    it is just plain common sence to me. and sometimes i do not
    agree with the code. but do it anyway

  • davidro1
    15 years ago
    last modified: 9 years ago

    i think you re not contradicting in your first four lines what i have said; (also it is obvious i never said the code spoke of gurgling...) in the end everything you have written agrees with everything i have written, and i could have written it myself, without contradicting anything i wrote previously. I concur with you -david