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Thread: Double fixture tee or double sanitary tee?

  1. #1
    DIY Member nc8861's Avatar
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    Default Double fixture tee or double sanitary tee?

    For DWV on a single vanity to double vanity conversion.

    Double sanitary:
    http://images.grainger.com/images/pr...MALL-1WHU8.JPG

    Double fixture:
    http://images.grainger.com/images/products/1CNT8.JPG

    Can anyone recommend an online site for ABS fittings such as this (also on a 4x3 closet bend)? My local shops don't have them.

  2. #2
    Forum Admin, Expert Plumber Terry's Avatar
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    If you are doing back to back toilets, it needs to be at least the double fixture fitting.
    And even with that, the waste from one toilet will cross over into the other arm, forcing the water up in the bowl, and then leaving it with less water.

    I becoming a big, I'm not a fan of any kind of cross for todays toilets.

    Last edited by Terry; 06-02-2010 at 04:40 PM.

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    DIY Member nc8861's Avatar
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    Thanks Terry - see OP though - these are two sinks on a double vanity.

    Another question - do these fittings have the slight drain angle built into the fitting?
    Last edited by Terry; 01-14-2010 at 06:22 PM.

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    Plumber patrick88's Avatar
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    The fitting you have shown are for vertical use.
    I'm just starting to work with an old friend of mine to bring solar electric and hot water systems, wind turbines, Flex Fuel Boilers, batteries, hydroponic gardening, books, pellet grills and more. Also the parts for DIY installation.

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    Moderator & Master Plumber hj's Avatar
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    Default fitting

    The double fixture fitting is the only one approved for back to back installations although it is possible a cross could slip by an inattentive inspector. The hubs have enough "slop" in them that they do not need built in pitch. You can install the pipe with the proper pitch, reverse pitch, or 'excessive' pitch just by holding the pipe at the desired angle as it cures.

    Last edited by Terry; 01-14-2010 at 06:22 PM.

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    Geologist sjsmithjr's Avatar
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    Default Here's a pic

    The pic below of double lav install (I believe it's from one of Terry's jobs) shows the correct configuration using a double fixture fitting. For the ABS fittings, Google "plumbing supply" and go with the famous one.
    Attached Images Attached Images  
    -Sam Smith
    Licensed Professional Geologist - AL, TN, KY

  7. #7
    Moderator & Master Plumber hj's Avatar
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    Default picture

    The only addition to the picture, unless it is dropping directly into a main line would be a cleanout tee beneath the fixture fitting. Although a snake will drop down the stack, removing a trap to clean the line is not a proper cleanout method in this area.

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    DIY Member nc8861's Avatar
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    Thanks all - I do already have an existing cleanout beneath the existing (single tee) fixture. I'm planning to cut above and below the existing single tee, & add my double tee.

    When adding a section of dwv pipe back in this vertical way, what's the best way to get couplings squeezed in there? In other words - if I come back with pipe to fit the exact length that I cut out, there won't be room to get couplings in where I need. I was thinking that I glue the bottom joint (between the tee and cleanout), and then on the top joint (above the tee), I use a rubber coupling? What do you all think?

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    DIY Member nc8861's Avatar
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    Sam - Just for the sake of explanation - why don't you use the type you pictured in the lower picture?

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    DIY Member nc8861's Avatar
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    And just to review - it's only when I'm doing a back-to-back installation (i.e. two different rooms) where I need a double fixture tee, right? Same room, two sinks = double sanitary. Correct?

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    Forum Admin, Expert Plumber Terry's Avatar
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    Where I am at, you would need a double fixture fitting, regardless.

    Last edited by Terry; 01-14-2010 at 06:23 PM.

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    Geologist sjsmithjr's Avatar
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    Quote Originally Posted by nc8861 View Post
    Sam - Just for the sake of explanation - why don't you use the type you pictured in the lower picture?
    My 50 cent explanation: the steel band in upper pic reinforces the coupling making for a connection that won't offset or separate. The coupling in the lower pic relies on the soil backfill to reinforce the coupling.

    Also, look closely at the coupling in the first pic - notice the stop for the pipe in the center and the ridges at either end to seal the joined pipes. The coupling in the second pic does not have these features.
    Last edited by sjsmithjr; 08-06-2008 at 06:22 PM.
    -Sam Smith
    Licensed Professional Geologist - AL, TN, KY

  13. #13
    Moderator & Master Plumber hj's Avatar
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    Default fitting

    The same fitting regardless of where the sinks are located.

  14. #14
    Master Plumber nhmaster's Avatar
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    The IPC will let you use the double san tee in the configuration that you want to use it for, HOWEVER if you have to snake the drain you'r gonna have troubles because the snake is going to pass straight through and not go down. We can not use double san tee fittings for back to back blow out type fixtures. I would follow Terry's advice and go with a double fixture Tee.

  15. #15
    Moderator & Master Plumber hj's Avatar
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    Default code

    The IPC is a cost driven code, and since a double fixture fitting costs more than a cross, the cross will be allowed even if it does cause operational problems later.

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