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Thread: Kitchen drain height problem

  1. #1

    Default Kitchen drain height problem

    I've seen similar threads on this topic, but I've got a unique situation that I've yet to see an answer for.

    I am in the process of completing a large kitchen remodel in a 1935 house. The kitchen sink is a double-bowl, 10-inch deep model. I have installed an In-sink-erator 444 model disposer. The drain out of the wall is currently about 3 inches higher than the traps. The water drains, but rests in the disposer as well as the trap.

    Obviously, the best option would be to lower the drain in the wall, but it is a cast iron pipe encased in concrete, hence the problem. Also, I can't change the sink, since it is undermounted with granite countertops.

    So, my questions are as follows:

    1. Is the current situation a code violation? ( I can drain the water by running the disposal that it only rests in the trap.)

    2. Can I cap the existing drain at the wall and drain the sink through the cabinet floor? I could tie into the ECO in the cast iron in the basement that serves the current drain. The existing drain pipe would have to remain to serve the vent anyway. I assume I could use a plastic fitting with an O-ring seal to connect to the cast hub, then add a long sweep Y with ECO?? (The vent would be about 6 inches downstream in this scenario.)

    Thanks in advance for any and all advice.

  2. #2
    DIY Senior Member e-plumber's Avatar
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    Default Kitchen drain height problem

    1. Is the current situation a code violation? ( I can drain the water by running the disposal that it only rests in the trap.)

    >Yes it is, trap seals are supposed to be I believe no less than 2" and no more than 4". Besides with water sitting in the disposer, it will most likely prematurely deteriorate and possibly void the warranty if a service technician needs to repair the unit<

    2. Can I cap the existing drain at the wall and drain the sink through the cabinet floor? I could tie into the ECO in the cast iron in the basement that serves the current drain. The existing drain pipe would have to remain to serve the vent anyway. I assume I could use a plastic fitting with an O-ring seal to connect to the cast hub, then add a long sweep Y with ECO?? (The vent would be about 6 inches downstream in this scenario.)

    >No, an S-Trap configuration is illegal. The best bet is what you do not want to hear, lower the sanitary t-wye in the wall of the kitchen sink base cabinet<
    e-plumber

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default drain

    The disposer is stainless steel so the water standing in it would not cause corrosion, but if will unbalance the disposer at first until the water is pumped out. That can create a fair amount of noise in a stainless steel sink.

    You are in the area between what is legal and what would work. There would be a way to do what you are asking, but the pipework might take up most of the area under the sink.

  4. #4

    Default

    We don't leave standing water, we pupm it out by running the disposer, but it is an inconvenience.

    As far as the trap, I wasn't thinking of using a S trap, but actually running a vertical pipe through the floor with a T-Y fitting for the P-trap to flow into. It would basically be about 3 inches forward of the existing pipe, but not in the wall. Technically, it could even tie into the existing stub out from the wall, but can two drains serve a single fixture?

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

    It will have standing water unless you run the disposer everytime you dump a glass of water into the sink. And if you do that consider replacing the disposer fairly quickly because when you use it as a "pump" you do not have water running in the sink so the motor seal is being damaged by the friction and heat build up.

  6. #6
    Plumber Deb's Avatar
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    Default Deb

    If you used the elbow that came with your disposer and a continuous waste, you can gain some height (maybe enough) by installing a disposer kit. The drain line for the disposer comes horizontally off the disposer with no 90s to a directional tee installed under the other bowl of the sink. The p-trap connects to this.
    Deb
    The Pipewench

  7. #7

    Default

    A disposer kit was the first thing I tried. It just doesn't gain enough height to matter. I cut down the disposer fitting to pick up as much height as possible, so the kit only raises the pipe about 1-1/2 inches.

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