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    Air Admittance valve under kitchen sink leaks

    Asked Sep 15, 2008, 01:52 AM 4 Answers
    Hi fellows,

    I live in HongKong in one of those 32 stories apartment buildings.

    Have "Silentrap" P-trap with Air Admittance valve install under the kitchen sink.
    Lately sewage water leaks from the Air in-take of the AAV when water drains.
    Local plumbers advised just to seal the valve with silicone. Shall I?
    No code whatsoever in HongKong to govern installation of AAV in apartment buildings.

    Any suggestion?

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    4 Answers
    massplumber2008's Avatar
    massplumber2008 Posts: 12,715, Reputation: 1206
    Senior Plumbing Expert

    Sep 15, 2008, 03:59 AM

    Definitely don't want to silicone/seal the unit.. ok? The sink would no longer have air mixing with waste and that can cause all kinds of issues down the road.

    Either the drain is getting clogged and you will need to snake the drain line to unclog the drain OR I would suggest that you purchase a new silenttrap with AAV and install the new unit...

    May be that you can take the seals from the new trap and just replace the seals on old trap..?

    Just don't silicone the leak!

    Let us know what you think here...

    Helpful (1)
    stustustu's Avatar
    stustustu Posts: 2, Reputation: 1
    New Member

    Sep 15, 2008, 07:51 AM
    Thank you Mark.

    I've been looking for an identical seal for the Silentrap AAV in Hong Kong of no avail.
    Local plumbers said seals from different manufactors won't work with Silentrap. Is that true ?
    Was told sewage lines in HongKong buildings are vented somehow. AAV is not required in households. What would possibly happen if I have to silicone the valve as a last resort ?

    massplumber2008's Avatar
    massplumber2008 Posts: 12,715, Reputation: 1206
    Senior Plumbing Expert

    Sep 15, 2008, 08:14 AM

    I imagine that if the AAV type of trap was installed in your unit then it must have been installed because there is no vent on the sink. You could try to silicone seal the unit and see if drainage becomes slower... but overall I am sure you will be better off to just replace the unit.

    Even if sink drains when you silicone the AAV most likely air won't be mixing with the waste water and drain will probably clog faster than it would have if AAV was in working order.

    I would replace it with a coupling and new trap if possible... or go to local home supply store and see what they recommend using in your case.

    I imagine the local plumbers are correct if they tell you seals don't swap out... same over here, usually!

    Keep me posted.. ok? I always like to find out results if possible.


    speedball1's Avatar
    speedball1 Posts: 29,303, Reputation: 1939
    Eternal Plumber

    Sep 15, 2008, 12:04 PM

    Hey Stu,
    What would possibly happen if I have to silicone the valve as a last resort ?
    You would convert your "P" trap to a "S" trap and lose your vent.
    Was told sewage lines in HongKong buildings are vented somehow
    If your trap goes down through the floor then you have a unvented "S" trap.
    There is no "one vent services all" in a building! To be "plumbing correct" and to follow safe plumbing practice every fixture that has a trap MUST be vented.
    But you're over there and you do what you got to do. If gluing the AAV shut and making it into a "S" trap stops the leak then do it. Years ago most of the fixtures in the States were "S" trapped and got along just dandy. True! "P"traps are protected from suction siphonage better then "S" traps but if that's all you have over in Hong Kong then that's what we'll work with. Tell us what the other traps look like? Floor or wall outlet? Regards, Tom
    Helpful (1)

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