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Discussion Forum

Disposal backs up into dishwasher

emaxxman00 | Posted in General Discussion on July 15, 2008 08:54am

Background:

  • dishwasher has been removed…waiting on a new one.
  • dishwasher drain hose connected to garbage disposal unit on end, empty bucket on other end.
  • hose is in a vertical U shape with crest higher than outlet on disposal

Problem – occassionally, water drains into bucket.  3 times in 3 weeks. 

There is a one-way flap on the drain hole connection from the disposal to dishwasher drain tube. 

Shouldn’t the one way nature of the flap keep water from going into dishwashwer drain tube?  What causes the flap to open.

The drain tube is not in contact with flap so it’s not keeping it open.

Is there a one-way valve that is small enough to go in between drain tube and drain hole on disposal unit?

Last thing I want is to have dirty sink water drain into my new dishwasher.

Thanks in advance.

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Replies

  1. mrfixitusa | Jul 15, 2008 09:50pm | #1

    The most common cause is the hose height and you've already ruled that out.

  2. [email protected] | Jul 15, 2008 09:50pm | #2

    My first guess, is that you are generating enough head pressure to push the water up over the "u", and past the one way valve. 

    I'm guessing that you are running the garbage grinder with a full sink of water above it, the drain line is partially clogged, or a combination of both.

    I would recommend installation of an actual air breaker assembly at the sink.  This will eliminate the possibility of the garbage grinder pushing water, and chunks of stuff,  back into the dishwasher. 

    1. emaxxman00 | Jul 15, 2008 09:59pm | #3

      Is there another term for the "air breaker"?  Google returns "air circuit breakers".  I'm not familiar with the term.

      1. ravz | Jul 15, 2008 10:01pm | #4

        air admittance valve..

        1. User avater
          BillHartmann | Jul 15, 2008 10:19pm | #6

          An air admitance valve is nothing like a DW air gap..
          .
          A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

      2. User avater
        BillHartmann | Jul 15, 2008 10:17pm | #5

        It forms an air break not breaker.But it is called an air gap. A google on dishwasher air gap will show it.http://www.plumbingsupply.com/airgap.htmlBut that does not really fix the problem. Just keeps it from backing up into the DW..
        .
        A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

        Edited 7/15/2008 3:19 pm by BillHartmann

        1. mrfixitusa | Jul 16, 2008 12:50am | #7

          Bill I look at a lot of houses and most have inexpensive dishwashers in which the racks are old, worn, and rusted.Did you know that rust gets into the motor and damages it?that's what I was toldThe appliance repairman also said it will ruin a dishwasher to let it set in a vacant house without being used.It's hard on the seal to let it set without being used

          1. User avater
            BillHartmann | Jul 16, 2008 03:59am | #8

            I suspect that there is a grain of truth to both of those.But most likely GREATLY OVERSTATED.Now that is only my opinion without any facts to back it up.But probably as much "facts" as the OP.Now I have heard of the dry seals and checked it out at one time.Someone told me that they where told to put mineral oil in one that is not used often to keep the seals from drying out.I did some check and I got a reply from one manufacture to the affect that there seals don't "dryout", but that mineral oil won't hurt anything..
            .
            A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

          2. mrfixitusa | Jul 16, 2008 04:27am | #10

            I've never used these but I have a cheap dishwasher and some of the wires in the racks are getting rustyHere is a product to cap it and keep the rust out of the systemhttp://www.improvementscatalog.com/product/id/101954.do

          3. calvin | Jul 16, 2008 05:28am | #11

            Tomorrow we're hooking up a dw I salvaged a couple yrs ago.  It's been sitting in a basement.

            I'll let you know if anything transpires that might mean something.A Great Place for Information, Comraderie, and a Sucker Punch.

            Remodeling Contractor just outside the Glass City.

            http://www.quittintime.com/

             

        2. emaxxman00 | Jul 17, 2008 03:09am | #12

          I read the write up on the air gap/break but was still not clear on how it worked.  It seems to almost be the same as an air admittance valve (which I am familiar with thanks the FHB magazine.)

          I installed the new dishwasher last night (Bosch).  It has an air vent tube clamped on the side.  Bosch instructs you to not do with, i.e. do not hook it up to anything.  It enters the dishwasher tub about midway up the tub wall. 

          Does this air vent tube function in the same role as the air break?

          1. User avater
            BillHartmann | Jul 17, 2008 04:41am | #13

            In general the function of an air break, of any kind, in plumbing, is to prevent contaminated water from "backing up" and mxing with potable water.One of the most common examples is the spount on a tube has to be a couple of inches above the rim of the tub.The counter top DW air gap has an outlet that connects to the DW and then a "funnel" that it drains into and connects to the house drain.If it or the drain cloggs up it will overflow on into the sink.I don't know what that is on the side of the DW..
            .
            A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

          2. calvin | Jul 17, 2008 04:44am | #14

            Bill, I don't know what thread it was in but that 2 yr stored DW leaked today.

            Worth taking it apart?A Great Place for Information, Comraderie, and a Sucker Punch.

            Remodeling Contractor just outside the Glass City.

            http://www.quittintime.com/

             

          3. User avater
            BillHartmann | Jul 17, 2008 04:55am | #15

            What leaked where?It is certain worth watching it while working to see where the leak is common from..
            .
            A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

          4. calvin | Jul 17, 2008 12:21pm | #18

            Water drips off the bottom of the motor housing where it connects up to the what I assume is the pump.  Dry where the water lines enter the pump.

            Constant drip while running.  Slows, but continues to drip after shut off.

            Stands to reason there's been no problems with the DW's I've given away from Kitchen remodels and then when I store one for use in my daughter's house (too long I guess) it craps out.A Great Place for Information, Comraderie, and a Sucker Punch.

            Remodeling Contractor just outside the Glass City.

            http://www.quittintime.com/

             

          5. User avater
            BillHartmann | Jul 17, 2008 03:30pm | #19

            It has been too long to remember the details. But I replaced a pump once. Don't believe that it was that hard or the parts that expensive. Off course the pump shaft has a new seal and a seal was in the kit for the seal from the pump to the DW bottom..
            .
            A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

          6. calvin | Jul 18, 2008 05:17am | #20

            Thanks Bill, I'll delve into this a bit more.

            No time to do it might end up the costly answer.A Great Place for Information, Comraderie, and a Sucker Punch.

            Remodeling Contractor just outside the Glass City.

            http://www.quittintime.com/

             

      3. Dave45 | Jul 17, 2008 06:34am | #16

        That would be "air gap" and they're readily available at any of the big boxes or hardware stores.

        Air gaps have to be installed correctly or you'll have drainage problems.  Once, I installed one in a way that it "flooded" and didn't provide the air gap.  It was quite a mess and it took me over an hour to figure out what I had done wrong. - lol

  3. User avater
    popawheelie | Jul 16, 2008 04:09am | #9

    What are you using the garbage disposal for? How are you using it?

    I've seen people use the garbage disposal for things it wasn't meant for.

    Jigs-n-fixtures is right about using it to pump out water. It wasn't designed for that.

    I've gotten our household to use it very little.

    We compost our scraps.

  4. Mooney | Jul 17, 2008 07:23am | #17

    I dont think it will do it with the dishwasher installed if you follow my advice.

    After the water goes through the screen it enters a pump that actually will hold water above it to some extent . Dont depend on it .

    Garbage disposal has a diverter in that drain hole going out that takes care of splash. Someone else said a full sink of water . Well , either that and its clogged or a full sink full with the disposal on thus casuing spash back . At any rate it wont enter the DW when its hooked up becasue of the way youre going to hook it up. .

    To take it to another level that it should be at anyway. They make a clamp that holds the hose and has a screw hole to attach the whole mess underneath the cabinet with a 3/4 screw. Most of the time I drill a hole that high into the side wall of the cabinet that holds it just under the counter top. Thats higher than the outlet of the GD. The last new one I put in came with such a clamp but I ran it through the hole I drilled. Water can not run uphill with out pressure and there wont be any even if your sink is overflowing . The DW pump will hold light pressure also of back feed. Just make sure your hose touches the underneath of the counter top or very close .

    Tim

     

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