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    bostopa's Avatar
    bostopa Posts: 3, Reputation: 1
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    #1

    Dec 27, 2012, 04:16 PM
    Lavatory Vent Question
    I have a lavatory that I'm replacing on the first floor half bath. It used to have cast iron and galvanized vents.

    Can I run a 11/2 vent from the lavatory? It will tee into a 2" main vent.

    Also the drain of that Lav look to drop right into the 4" pipe just about a foot before the water closet flange.

    I would also bet that the 2" vent is also tied there. I can see it since the sub follr is still there push the basement has a ceiling. I'll try and take a pic to submit.

    Thanks John.
    massplumber2008's Avatar
    massplumber2008 Posts: 12,832, Reputation: 1212
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    #2

    Dec 27, 2012, 04:20 PM
    Hi John.

    A picture would be helpful to confirm things, but as you present things, YES, you can run an 1.5" vent from the lavatory and connect it into an INVERTED tee fitting of the 2" vent line IF this vent was 1.5" to begin with! If the vent was 2" then you must run a 2" vent as this sink drain/vent may WET VENT the toilet and that requires a 2" vent.

    The connection into the 2" vent must be a minimum of 42-44" off the finish floor the sink is on, OK?

    Of course, the sink must also have a PTRAP!

    Mark
    bostopa's Avatar
    bostopa Posts: 3, Reputation: 1
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    #3

    Dec 27, 2012, 04:34 PM
    I'll post a pic... if I can figure out how to. Don't think I can on this site
    massplumber2008's Avatar
    massplumber2008 Posts: 12,832, Reputation: 1212
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    #4

    Dec 27, 2012, 05:22 PM
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    bostopa's Avatar
    bostopa Posts: 3, Reputation: 1
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    #5

    Dec 27, 2012, 08:10 PM
    Here are the pics
    massplumber2008's Avatar
    massplumber2008 Posts: 12,832, Reputation: 1212
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    #6

    Dec 28, 2012, 06:41 AM
    Looks like the toilet has a dedicated 2" vent so it looks like running an 1.5" vent for the sink works fine!

    Where is the stubout for the sink drain? It should be stubbed out (off the vent pipe) at about 18-20" off the finish floor height.

    Back to you...
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