2 Air Admittance Valves on double sink, IPC 2009

Discussion in 'IPC Plumbing Code Questions' started by mtcummins, Jun 25, 2010.

  1. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    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...
  2. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    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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  3. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    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
  4. Terry

    Terry Administrator Staff Member

    Messages:
    15,423
    Location:
    Bothell, Washington
    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.

    [​IMG]
    Last edited: Jun 26, 2010
  5. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    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
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,272
    Location:
    Cave Creek, Arizona
    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.
  7. Rich B

    Rich B DIY Senior Member

    Messages:
    283
    Location:
    New Jersey
    This website and the pictures might give you some ideas that help:
    http://www.hammerzone.com/archives/kitchen/sink/drain/02/replace_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: Jun 26, 2010
  8. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    I'm with HJ. Either you are misunderstanding him or he should be asking folks if they would like fries with that. :)
  9. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Yes.

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

    Both sinks through one trap:
    [​IMG]

    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.
    [​IMG]
    Last edited: Jun 26, 2010
  10. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    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: Jun 26, 2010
  11. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    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.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,272
    Location:
    Cave Creek, Arizona
    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.
  13. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    HPIM2941med.JPG


    Do this and then dump the trap into a sanitary tee with the AAV off the top of the tee
  14. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    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?

    Attached Files:

  15. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    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? :)
  16. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    I'm thinking he's more of a honey mustard type of guy...
  17. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    I talked with one of the General Contractors and the head of maintenance for one of the largest real estate companies in Pittsburgh today, who just happens to be doing a gut remodel of the house next door to mine, and he said that 2 traps and 2 vents is the normal requirement in Pittsburgh for a double sink.

    This is how their plumbers rough in a double sink for AAVs, which they had to do in their kitchen, just like my house. Picture is a little dark, but you'll see they bring 4 pipes through back of cabinet, bottoms each get a trap to sink bowl or disposal, tops go up to an AAV. This is apparently required here, as the city has the right to add to the code restrictions.

    Go figure.

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  18. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Why in the world would you use AAVs like that if you have an open wall like that? Is there a room above you that' finish dry walled? If so cut out a joist space (or atleast a hole on the bottom) and run a vent up into the attic and tie it into an existing vent.

    And the city ALWAYS has the final say because if you look in the code book somewhere it will saying to the effect that the authority having jurisdiction always has the final say. If the inspector said you could run all your drainage up hill and through a 1.5" line with no venting then by all means you could do that! However if they say you have to use all 4" piping with 8" venting then you'd have to do that too! Ok a little extreme of an example I know :D
  19. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    I don't know in his case, I didn't trace it down to see why they couldn't vent it. The whole house is gutted, and they've hard vented the laundry rooms, all the baths, etc, just not this kitchen sink. These houses are 3 stories, so the attic is either non-existent (flat roofs), or 2 stories up. I have the exact same situation, in that I was able to hard vent everything in my house while I had it gutted, but I have an exposed brick wall as my kitchen backsplash, so there was no way to feasibly route a vent line, other than to do an island loop, which I'm not too keen on either. It was literally impossible w/o completely changing the design of the house or creating a structural nightmare. I'm not sure in my neighbor's case, but they went to good lengths to vent everything else, so there must have been a good reason.

    I actually wouldn't be surprised if you start to see things like this creeping into the code, but who knows how long that will be. Pittsburgh has been requiring this arrangement for some time now, as they say its better venting - maybe they're just crazy, but I could see how it could theoretically be a better venting situation. Of course, I know nothing about code up in the frozen tundra, so maybe not for you...
  20. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Yeah sometimes it's hard or damn near impossible to get a vent up.

    But you won't see that stuff "creeping" up in the code I don't think because it's just a bit out to lunch. And yes you're right you will get better venting out of having 2 AAV but you'd also get better venting out of having 6" vents picking up all your fixtures. But you don't see inspectors making people put in 6" vents for sinks.

    But if that's the way your inspector wants it you can't really argue with them because they have the final world. The drawing you did up on your last couple of posts there will work just fine for what you need.

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