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Thread: New deeper kitchen sink causes slight DWV problems

  1. #1
    DIY Junior Member mooch91's Avatar
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    Default New deeper kitchen sink causes slight DWV problems

    Installed a new deeper kitchen sink (went from 7" to 9") and very slightly underestimated the difference in the DWV piping. I thought I wasn't going to have a problem.

    I'm not way off, if I didn't have a dishwasher to drain everything actually would be fine, but I'm about 1/2" off in getting a dishwasher tailpiece to fit. Please see the pictures.

    I'm sure the right answer is to open the wall and lower the drain point on the stack, but is there an alternative? Either lowering the p-trap slightly or connecting the dishwasher drain elsewhere? I've already got the shortest sink basket I could find and could not find a dishwasher tailpiece with a higher wye. Do they make a tailpiece with a higher wye?

    Thanks in advance.




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    DIY Senior Member gardner's Avatar
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    I'm curious what's off to the right in your first picture. Is there another fixture or something that might me more amenable to the DW drain?
    You might find a suitable drain saddle tap that could be fitted in a more convenient location on a standard tailpiece. The ones I've seen are for R-O filters and have 1/4 connections though. You'd need 1/2 or 3/4.
    If you're really desparate, I think it would be possible to fabricate DW nipple tailpiece from a plain brass one, a brass nut and brass barb cut and soldered together.

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    DIY Junior Member mooch91's Avatar
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    Quote Originally Posted by gardner View Post
    I'm curious what's off to the right in your first picture. Is there another fixture or something that might me more amenable to the DW drain?
    You might find a suitable drain saddle tap that could be fitted in a more convenient location on a standard tailpiece. The ones I've seen are for R-O filters and have 1/4 connections though. You'd need 1/2 or 3/4.
    If you're really desparate, I think it would be possible to fabricate DW nipple tailpiece from a plain brass one, a brass nut and brass barb cut and soldered together.
    To the right is the second half of the double sink. I followed the plumbing design from the existing sink which had two separate p-traps for the individual sides of the sink that come together in a double-wye which you can see in the first picture.

    I woke up thinking about fabricating one this morning but I couldn't visualize a diy way to do so. Sounds like more of a brazing operation to me.

    Starting to get desperate... Thanks for some of your thoughts.

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    Moderator & Master Plumber hj's Avatar
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    The way I would have done it would have been to use that double Y, but install a third "P" trap into the center inlet. You could still do it by using a brass male DeSanko/Marvel connector/trap connector, (whichever you want to call it in your area), with a tubular trap into it. The dishwasher drain WOULD then go to a countertop air gap fitting, and its drain hose would have gone to the third trap. The dishwasher MUST beconnected to the drain line with a trap AND an air gap so a "saddle tee", which would be illegal anyway, is not an option. Normally, a garbage disposer or branch tailpiece would provide the air gap function.
    Last edited by hj; 12-02-2010 at 07:39 AM.

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    DIY Junior Member mooch91's Avatar
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    Found a "low inlet p-trap" that looks like it loses about 1" on the inlet side which is just about what I need... assuming I can find one in the stores, any thoughts on this as an option?

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    Master Plumber-Gas Fitter shacko's Avatar
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    Go over to your post on the other forum, I left you a link for a return bend, that should be the easiest way to fix your problem

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    In the Trades Jerome2877's Avatar
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    I would tie the drains from the sinks together and install the dishwasher Y in the section between the two. Then cap the other drain with a cleanout cap.

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    One who lurks Basement_Lurker's Avatar
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    Quote Originally Posted by Jerome2877 View Post
    I would tie the drains from the sinks together and install the dishwasher Y in the section between the two. Then cap the other drain with a cleanout cap.
    It doesn't look like there's enough height to be able to do that configuration.

    Using a p-trap, instead of the j-trap you have shown, will most likely give you just enough room to install the dishwasher inlet tailpiece. If your code requires the installtion of an air gap fitting, then Hj's reccomendations are your best bet.
    Broken promises don't upset me. I just think, why did they believe me? -Jack Handy


    www.blackbirdkitchenandbath.com

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    DIY Junior Member mooch91's Avatar
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    It may not be code, and it may not be elegant, but as an engineer in my spare time I can't identify any reason why the following is necessarily a bad idea. The connections are robust and, if anything, a deeper trap provides a better seal. The only issue I can think of is that the velocity through the pipe is slowed a tad which could affect self-cleaning but is there any scientific problem with a small increase in the depth of the trap?



    Basically, I replaced the p-trap j-bend with a "repair j-bend" (female coupling on the end that ties to the arm) obtained from HD and used a slip joint coupling threaded in between the two. Absolutely no leaks and the piping is tight.

    I'd like to make this temporary (really needed to get the sink working again) and still try a low-inlet trap or a sch 40 trap (which would save me a little bit of height as noted above). Once I settle in on the permanent solution I'll replace the plastic tailpieces with brass.
    Last edited by mooch91; 12-02-2010 at 08:31 PM.

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    DIY Junior Member mooch91's Avatar
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    Quote Originally Posted by Basement_Lurker View Post
    Using a p-trap, instead of the j-trap you have shown, will most likely give you just enough room to install the dishwasher inlet tailpiece.
    I thought I was using what was called a "p-trap" which contained a "j-bend". Not sure I completely understand the difference. Any pictures of the two so I can understand? Thanks.

  11. #11
    Moderator & Master Plumber hj's Avatar
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    I have been in the plumbing business for over 60 years and I also do not know what he means by a "J" bend instead of a "P" trap, since the trap portion of a "P" trap IS the "J" bend. A low inlet trap has the same deficiency as reversing the "J" bend on your regular trap, namely, the "socket" where the vertical tailpiece enters the trap is very shallow, so it can make a tenuous connection which may easily separate if bumped.

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    DIY Junior Member mooch91's Avatar
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    This should do, if I can find it (low-inlet trap):

    http://www.keeneymfg.com/cad_drawing...PDF?1260481939

    Gives ~ 2" pipe insertion if the drawing is accurate. The inlet to the pipe sits between 3/4 and 1 inch lower than a standard trap. No re-work of my existing setup needed.

    As compared to the typical trap:

    http://www.keeneymfg.com/cad_drawing...pdf?1260481915

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    Moderator & Master Plumber hj's Avatar
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    That will work, IF you can ever find one. I have never seen one in any of my supply houses.

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    DIY Junior Member mooch91's Avatar
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    Quote Originally Posted by hj View Post
    That will work, IF you can ever find one. I have never seen one in any of my supply houses.
    Sent an e-mail to the company (Keeney), will report back with what I find. They seem to be a fairly big supplier for tubular and other plumbing components. They were very helpful with another recent request, I am hopeful this time will be the same.
    Thanks!!!

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    Master Plumber Redwood's Avatar
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    Redwood's crystal ball says, "I see a stanky dishwasher in your future."

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