Air admittance valve - "above the flood level rim"?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by schmeel, Jul 26, 2007.

  1. schmeel

    schmeel New Member

    Hello folks,

    I am trying to detemine if I can use an air admittance valve underneath my kitchen island sink (in Ontario, Canada).

    I am installing a kitchen island sink, and it seems impractical (impossible?) for me to vent it - even using the techniques described in and in

    I've read about air admittance valves. However in the Ontario Building Code, Section ("Air Admittance Valves") states that "The air admittance valves shall be located, (a) above the flood level rim of the fixture it serves, ..."

    In Section (Defined Terms) this definition is provided:

    Flood level rim means the top edge at which water can overflow from a fixture or device.

    So my question is: can I use the AAV under the sink? It seems to me that won't be above the flood level rim. However elsewhere it seems people are suggesting that you can do this (perhaps they are not in Ontario...).

    I'd appreciate any help anyone can offer!

  2. Terry

    Terry Administrator Staff Member

    Bothell, Washington
    According to the code you listed, NO.

    This is one of those times, that you may want to talk to the inspector of your job before you start. He may have an idea of what is locally done that they accept.

    I'm I'm plumbing from scratch, I often do the Island Vent.
    Whenever possible, I find a way to vent through the roof.
    There are a few occasions, on a retrofit, that I've used an AAV. Air Admittance Valves
    (1) Air admittance valves shall only be used to vent,
    (a) fixtures in buildings undergoing renovation, and
    (b) installations where connection to a vent may not be practical.
    (2) The air admittance valves shall be located,
    (a) above the flood level rim of the fixture it serves,
    (b) within the maximum developed length permitted for the vent,
    (c) not less than 150 mm above insulation materials, and
    (d) installed in a location not subject to back pressure.
    (3) Air admittance valves shall,
    (a) only vent fixtures located on the same storey, and
    (b) be connected to the horizontal fixture drain. Installation Conditions
    (1) Air admittance valves shall not be installed in supply or return air plenums, or in locations where they may be exposed to freezing temperatures.
    (2) Air admittance valves shall be installed in accordance with the manufacturer’s installation instructions.
    (3) Air admittance valves shall be rated for the size of vent pipe to which they are connected.
    (4) Installed air admittance valves shall be,
    (a) accessible, and
    (b) located in a space that allows air to enter the valve.
    (5) Every drainage system shall have one vent that terminates to open air in conformance with Sentence

    Last edited: May 31, 2012
  3. aav valve

    It sounds like it is ok to use one if
    you simply put it above the flood rim
    of the they are use up there in some instances...

    being an isalnd , that is impossible to do,
    but usually most of the time if you simply
    take it as high as possible under the sink
    and run at least a 2 inch drain over to that
    island sink will usually fly....

    unless you get an insepctor who has had a
    bad it would be wise to pass it by him
    for aproval

  4. molo

    molo Member

    cold new york
    How can you tell if an AAV is working?
    Are some brands better?
    I put one in the other day and expected to see the black plunger thing (inside the top cover) going down as it was draining, but it didn't move.

  5. AAV valves

    I put a bunch of them in my old house
    a while back.....

    when alarge volume of water was discharged
    fromthe washing machine , you could heat the
    valve actually chriping or sucking air into the line...

    of course , this was a 100 year old home with no
    way to get a vent up three stories so I put one under my vanity just high enough up not to be seen, and it works just fine, I slapped one on the laundry outlet and I put
    a third one in behind the tub just for kicks.....

    I would think that the only way you would know that
    they wer not working would be the traps getting sucked
    out and the smell of sewer gas .....

    I suppose that its probably not a bad idea to change them every 10 years or so...

    but in this state they are not even necessary under kitchen sinks anymore..

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