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Thread: 2 Air Admittance Valves on double sink, IPC 2009

  1. #1
    In the Trades mtcummins's Avatar
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    Default 2 Air Admittance Valves on double sink, IPC 2009

    Hey All,
    My local inspector allowed me to use AAVs on my kitchen double sink, as there was no good way to hard vent it. He said that a double wye with an AAV off the top was not allowed in our municipality, and that I have to have 2 AAVs. I guess a 2" hard vent is ok off the top of a double wye, but the AAV is not sufficient.

    So, 2 AAVs means 2 traps, and I'm trying to figure out how to plumb this legally. I know I can make it work, just want to verify that the way I'm doing it is legal. I'm trying to attach a picture of what I'm thinking I'll do, but it doesn't seem to be working. I'll keep trying...

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    In the Trades mtcummins's Avatar
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    Ok, I think it attached the picture this time.

    I've got a 2" inlet through bottom of cabinet, then this is what I was thinking of building off of that. There are 2 AAVs in the middle (with the orange bands), and its showing 1 of the 2 traps on the right, there would be one coming out of the left side as well (have to buy another trap, only had 1 on hand).

    Does this seem feasible/legal? Any thoughts on a better way to do it?

    Thanks,
    Mike
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    In the Trades mtcummins's Avatar
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    Oh, and if it makes a difference, the left side is being attached to a disposal, hence it being lower than the right trap. I'll also have the AAV's up a bit higher than they're shown, to get the minimum 4" above trap requirement (I'll have them probably about a foot above, for good measure).

    Thanks in advance.

    Mike

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    Forum Admin, Expert Plumber Terry's Avatar
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    The inspector won't like the wyes there.
    You should have santees, and the vent should pull off the vertical of the santee.
    The wye creates an S trap which is illegal.

    Last edited by Terry; 06-26-2010 at 10:23 AM.

  5. #5
    In the Trades mtcummins's Avatar
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    Quote Originally Posted by Terry View Post
    The inspector won't like the wyes there.
    You should have santees, and the vent should pull off the vertical of the santee.
    The wye creates an S trap which is illegal.
    So to do this and get 2 AAVs in, I'd use a 2" x 1 1/2" x 1 1/2" wye and 1 1/2" 45 at the bottom to turn the 2" drain into 2 side-by-side vertical 1 1/2" drain pipes, each with a santee pulling a trap off the horizontal and an AAV off the vertical?

    I hope that makes sense, I can't piece it together right now to take a picture, not at the jobsite right now.

    Thanks again,
    Mike

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    Moderator & Master Plumber hj's Avatar
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    And why aren't you using a SINGLE 2 x 1 1/2 sanitary tee, a SINGLE trap, and a disposer continuous waste to connect the two sinks. (By the way, your inspector is either an idiot or does not like AAVs so he is making it as difficult as possible for you). Installed the way your picture shows it makes BOTH AAVs ineffective and completely useless.

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    DIY Senior Member Rich B's Avatar
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    This website and the pictures might give you some ideas that help:
    http://www.hammerzone.com/archives/k...eplace_old.htm

    I have the exact same setup in my kitchen and it works perfect. It was originally plumbed with no vent at all and running one up thru the roof would have been impossible.......I have an old double sink just like in the pictures. I used a Studor AAV.....It can be changed in minutes and is just above the bottom of the sink just behind it....
    Last edited by Rich B; 06-26-2010 at 04:58 PM.

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    In the Trades Wally Hays's Avatar
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    I'm with HJ. Either you are misunderstanding him or he should be asking folks if they would like fries with that.
    Perception is 3/4 of reality

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    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Quote Originally Posted by mtcummins View Post
    Any thoughts on a better way to do it?
    Yes.

    Red dot is the AAV and the yellow dot is a 2" line cleanout.

    Both sinks through one trap:


    Both sinks with individual traps draining into a common 2" branch line via 2x1.5x1.5" double san-t (or double fixture tee if you can get it) with a 1.5" vent coming off the top into a 1.5" aav.
    Last edited by Doherty Plumbing; 06-26-2010 at 08:58 PM.

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    In the Trades mtcummins's Avatar
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    Thanks everyone for your input.

    I understand now how my first picture creates an S-trap. I was previously unaware that you could create one over that distance, but understand that concept now. Thank you for helping me there Terry, I researched it more after you told me that.

    Rich, I came across that website actually as I was trying to find information about this, but as this requirement is either odd to Pittsburgh or to my specific inspector, there doesn't seem to be anything about what I'm being asked to do.

    Wally - haha, I dunno if its him or the city on this, but I know the city is nuts about a lot of things. Many of the city people should be asking if you want fries with that... The inspector was fairly gracious (didn't have to fight for it, he just let me do it) in allowing me to use AAVs in this case, but made me put in a vent in another location where venting was fairly difficult, but more feasible. When he said I could do the AAV, he said that a sanitary cross (i meant to say cross in first post, not double wye) with an AAV above it is not legal here, and that I had to have separate AAVs for each bowl. Not sure if that applies all the time, or just in the AAV case, or just b/c the inspector felt like it in this case, but thats what he wants...

    So, none of the pictures/descriptions above work to meet that requirement. I would normally do what Terry has posted with either an AAV or preferably a vent, but he wants 2 AAVs. I don't like to argue with inspectors, I tend to find that it makes my life more difficult...

    So, do I split the drain and treat it as 2 separate drain lines coming up, each serving one bowl of the sink, as if they were 2 separate single bowl sinks? Is there any other way to get 2 AAVs in there? One last question... is the cleanout required/necessary since you could run down through the AAV, or is it more of a convenience thing (lower, easier to get to)? I've got no problem adding that, might as well do things the best way possible while I'm tearing it apart, just curious about code requirements.

    Sorry my town is crazy and likes to complicate things...
    Last edited by mtcummins; 06-26-2010 at 10:47 PM.

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    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    You can take the same concept I drew up for you but branch it off into two seperate lines. The design of the system would be virtually the same though.

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    Moderator & Master Plumber hj's Avatar
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    I have installed thousands and thousands of double sinks and have ONLY used 2 traps when the drain from the wall was too high to use the conventional continuous waste. I don't know why you are not using one in your situation. There is no way the inspector can NOT approve it since it is the "standard" method of connecting a double sink to the drain.

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    In the Trades Wally Hays's Avatar
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    Name:  HPIM2941med.JPG
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    Do this and then dump the trap into a sanitary tee with the AAV off the top of the tee
    Perception is 3/4 of reality

  14. #14
    In the Trades mtcummins's Avatar
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    I would love to do a standard, conventional hookup - really I would. I'm not trying to make it more complicated, but Pittsburgh is known for adding ridiculous extra rules to the code. This either is or is not one of them, but my inspector specifically said I can't do a sanitary cross with an AAV above it b/c I had to have 2 AAVs. I can definitely see how my first design would fail now - thanks for showing me that those are indeed S-traps - but that doesn't change the fact that my inspector will probably fail me if I don't do 2 AAVs.

    So, whether or not you would do it personally, is there any code/safety/practical (other than extra work and materials) reason to not do what I've drawn below, to meet his requirements? I'm not a huge fan of AAVs myself - prefer to do real venting when possible, so maybe having 2 of them will help increase their effectiveness? Especially when the D/W, sink, and disposal are all dumping into the drain line at the same time? Or potentially reduce the chance of a clog if one of them fails?

    The red dots in the sketch are AAVs, the yellow dot a 2" cleanout, the blue lines P-traps, and of course santees to tie in. Only wye is where i split the 2" riser into two 1.5" lines, there shouldn't be any problem with that, right?
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    In the Trades Wally Hays's Avatar
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    That's fine. A stooopid waste of materials, time and money, but fine. Tell your inspector to read a code book once in awhile. Barbecue or sweet and sour sauce sir?
    Perception is 3/4 of reality

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