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Thread: Plumbing 2 Dishwashers SideXSide

  1. #1
    Network Engineer rmelo99's Avatar
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    Default Plumbing 2 Dishwashers SideXSide

    I need some help with plumbing 2 dishwashers both supply and drain. First time ever doing 2(in one kitchen anyway :-)

    They will both be located next to each other on the left side of the sink.

    I am unclear on how to tackle this setup. All the dishwashers I have plumbed have had their supply fed from a second valve under the sink base and the drain line piped with flex tube into the sinks drain line.

    I also have done one house where the d/w drain line had it's own drain/trap in the sink cabinet that was setup like a washing machines drain. The flex tube just went into that.

    I am unclear how I would deal with the plumbing for the unit furthest away from the sink and even the one closest.

    I am above basement and have access to plumb this how ever is necessary....within reason.

    1.) I like having access to a shut off supply valve under the sink, incase of emergency. Can I or should I plumb 2 stops under the sink, one for each d/w and then run supply to each unit using flex braided SS? Or should I install hardpipe to behind each unit and simply have a shut off valve located under the sink?

    2.) What is the optimal/proper way to run drainage for these units? Is it still back out the sink trap/drain? Can each d/w have it's own drain line?


    Thanks
    Rem

  2. #2
    Plumber krow's Avatar
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    1) locate 2 seperate stops for dishwashers and 1 for sink, The SS tubes are the easiest to work with

    2)For best results and better access to drain hoses, under the sink connections are better. I have seen too many traps under the floor with little or no access to plugged DW drains. A nightmare to unplug

  3. #3
    Plumber krow's Avatar
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    Typical installation for 2 DW units
    Attached Images Attached Images  

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    DIY Senior Member Mike Swearingen's Avatar
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    A couple of other issues to deal with:
    Does your local code require air gaps on all dishwashers? If so, you'll need two.
    Does your local code require a separate dedicated electrical circuit to a dishwasher? If so, you'll need two 15 amp breakers with 14/2-with-ground wiring, which will likely comply. However, if you're running new circuits, I would go ahead and run 12/2-with-ground off 20 amp breakers just in case someone ever wanted to install heavy-duty dishwashers in the future.
    Good luck!
    Mike

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default dw

    You can make the hot water connections anyway you want to. A single valve with two outlets, a double valve with a single inlet, two separate stops, etc. The drains will connect separately. Either to a disposer and a branch tailpiece, or two branch tailpieces if there is no disposer. If a DW has its own trap, and is done "legally", then it is a possible source of flooding because of the open gap. If it is not done properly, then it can be a source of contamination if the drain backs up into the dishwasher.

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    Network Engineer rmelo99's Avatar
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    I have wiring in place for 2- 20 amp breakers. Local plumbers have said no air gaps required but I will check with the city plumbing inspector next week.

    If I do need to use an air gap I think I saw on the board here a two to one air gap for multiple units. Will that work?

    Am I going to run into issues with such a long drain hose for the 2nd unit? What would be the correct way for the D/W to have it's own drain?

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    Network Engineer rmelo99's Avatar
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    anyone? Makin sure i didn't get forgotten :-)

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    Plumber krow's Avatar
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    In most cases 98% of the time, you do not need an air gap because most DW,s are equipt with built in check valves. You only have to put a high loop under you counter.

    Running more hose will not give you any issues. You will only need to extend an extra 3FT max to reach your required destination.

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