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How to vent a floor sink when the nearest wall is ~10' away?

Discussion in 'Plumbing Codes' started by Michael.L, Jun 7, 2018.

  1. Michael.L

    Michael.L Sawhorse

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    I'm laying out the floor plan for a small cafe. There will be a coffee bar at the service counter with a 3-compartment sink. The 3-comp sink's drain will be indirectly plumbed to a floor sink below with a required air gap. But the closest wall is 9.6 feet from the location of this floor sink. Is it acceptable for the vent to be that far from the floor sink trap? Do I just upsize the fixture arm drain pipe to ensure that the vent connection opening remains above the trap weir?
     
  2. Keystone

    Keystone Sawhorse

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    Why not use an Auto Air Vent?
     
  3. Sifu

    Sifu Gold Member

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    Combination waste and vent.
     
  4. mtlogcabin

    mtlogcabin Sawhorse

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    If the 3 compartment sink is also being used as a food prep sink then it should be going to a grease interceptor

    3 " drain will allow 12 feet from the trap to the vent
     
    Michael.L and Pcinspector1 like this.
  5. Michael.L

    Michael.L Sawhorse

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    It's not a food prep sink, but it will be used to wash out milk steaming jugs and blender jars. It will be drained to our grease interceptor.

    Are you sure? According to this graphic, a 3" drain will only allow a max trap arm length of 6 feet, and that I'd need a 4" or larger to get the max trap arm length to 10 feet.

    [​IMG]
     
    #5 Michael.L, Jun 7, 2018
    Last edited: Jun 7, 2018
    jar546 likes this.
  6. Michael.L

    Michael.L Sawhorse

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    One reason is that they tend to make a noise like a "whoopie cushion." Not exactly what you want customers to hear at your cafe's service bar.
     
  7. Michael.L

    Michael.L Sawhorse

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    Like this?
    [​IMG]

    I don't know if the existing sewer line under the slab is deep enough to allow this type of configuration.
     
  8. Keystone

    Keystone Sawhorse

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    I can understand that.

    mtlogcabin is spot on, if your using local jurisdiction uses IPC then you will be okay. Chapter 9, Venting from the IPC allows up to 12ft when using 3" drain at 1/8" slope.
     
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  9. Pcinspector1

    Pcinspector1 Platinum Member

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    2012 IPC TABLE 909.1
     
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  10. Michael.L

    Michael.L Sawhorse

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    Thank you for the code reference. That's always better than random images culled from the interwebs. :p

    My apologies to Mtlogcabin for doubting you!
     
  11. ADAguy

    ADAguy Sawhorse

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    What you show is an island vent, commonly used on residential kitchens.
     
  12. Michael.L

    Michael.L Sawhorse

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    Our service bar will essentially be an island. I'm curious: why plumbers would install an island vent like that rather than just upsizing the trap arm pipe to 3" (or 4")?
     
    jar546 likes this.
  13. mtlogcabin

    mtlogcabin Sawhorse

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    My apologies for not including the code reference table
     
  14. HForester

    HForester Member

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    AAV = Air Admittance Valve
     
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  15. James Davis

    James Davis Registered User

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    the majority of inspectors don`t like/allow AAV`s
     
  16. mtlogcabin

    mtlogcabin Sawhorse

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    The UPC does not allow the use of an AAV. However they can be permitted under alternate materials and methods which we have done on a case by case decision for existing buildings

    The IPC does allow them so unless the AHJ amended that section of the IPC to not allow them then inspector is not following the code and acting upon his personal wants and desires
     
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  17. RJJ

    RJJ Platinum Member

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    MT is correct on both accounts. The IPC does allow AAV, but you have to have access. The 3" drain should work just fine, if you want to be on the safe side go to 4" and you will have plenty of air.
     
  18. Keystone

    Keystone Sawhorse

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    I'm not a fan of upsizing that small of a fixture count due to less pipe wash, leaving a greater potential for dried particle build up within the pipe.
     
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  19. mark handler

    mark handler Sawhorse

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    AAVs are not included in the UPC or the CA Plumbing Code But does not prohibit the use.
    Just because they are not included does not mean they are prohibited.

    CA allows the AHJ, to use discretion, on a case by case basis. This however, does not extend to commercial use.

    upload_2018-8-11_7-41-6.png
     
  20. ICE

    ICE Sawhorse

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    Air admittance valves let air in but do not let air out. A plumbed vent will prevent air pressure from pushing the water out of the trap. Now I don't know if that is reason enough to ban them but I get the feeling that my jurisdiction is less than impressed.

    As an aside, I don't know but I've been told that they do fail.....there was a mold buildup....some colorful stuff of the genus IMUS (It'll Make Us Sick).
    I wonder what became of Don.
     

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