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Discuss Air admittance valve issues in the Plumbing Forum area at UKPlumbersForums.co.uk.

  1. AliMan22

    AliMan22 New Member

    Hi all
    Our externally vented ‘traditional’ stack vent (through the roof) kept leaking through the roof with rain water so to solve the issue for good we cut off the stack pipe in the loft and fitted an air admittance valve and got a roofer to patch the roof in late April.
    All was fine until about 2 weeks ago when a horrible smell was coming through en suite shower plug hole. I’ve tried everything, drain cleaners etc but to no avail. Husband checked manhole and all clear so no blockages.
    I emailed flo plast who said AAVs are factory tested so doubtful it’s faulty especially as only a few months old.
    Anyway last night husband got in loft and took AAV off altogether and the smell has now gone from our plug hole. (Loft stinks though and may be a health hazard right now?!)
    So I have lots of questions!
    Is it worth trying a new AAV or is it just that an AAV isn’t quite right for our system? Whenever we flushed main loo the AAV made a racket and released pressure from AAV. Maybe this was pulling water out of traps?? But not sure how this could be solved (can toilet pressure be adjusted?).
    We are thinking we should extend soil pipe back through roof and have an air vented system again. Would you agree? What would be the best way to vent back through the roof and is it a plumbers job or a roofers?
    I’ve attached a photo so you can see the loft set up.
    Sorry for all the questions. I thought an AAV was the answer to all our problems but nothing but trouble! I’m now regretting cutting the stack pipe off in the loft in the first place!

    A148D4BF-ED39-4AAD-B66A-7E53F7C1EF50.jpeg
     
  2. chris watkins

    chris watkins Plumber Top Contributor!!

    It is strange that it worked for a few months so might be worthwhile getting it checked out. Alway easy with hindsight I know but it would have been much easier to fix the the leak roof with a lead slate, there is a reason the vents were installed in the first place.
     
    • Agree Agree x 1
    Last edited: Aug 9, 2018
  3. AliMan22

    AliMan22 New Member

    We did initially get roof repaired the November before but it started leaking again so that’s why we went with the AAV in the April. In hindsight I wish we would have persevered with the roof.
     
  4. AliMan22

    AliMan22 New Member

    Just saw all your responses in red. Thanks so much. I think reverting to an air vented system sounds like the best option. Thanks.
     
    • Like Like x 1
  5. Karl

    Karl Member

    It should definitely be taken out through the roof, the waste system needs to be able to breathe to the atmosphere, the best thing to fit is a vent slate, not an eye sore and easy to fit. A builder/roofer can fit this and just connect to soil pipe using a flexi (which is normally supplied with the kit) hope this helps
    https://www.screwfix.com/p/glidevale-universal-tile-ventilator-grey/8821t
     
    • Informative Informative x 1
  6. AliMan22

    AliMan22 New Member

    Just what I was looking for. Thank you so much!
     
  7. chris watkins

    chris watkins Plumber Top Contributor!!

    "Beauty is in the eye of the beholder" I love to see a vent pipe termination especially those old lead ones with the fancy tops. :D
     
    • Like Like x 1
  8. Maryplumb

    Maryplumb Plumber GSR

    Agree with all above you need a roof vent. AAV lets fresh air in when appliances discharge but should not let foul air out. Whenever it started doing that it was faulty, easily happens if it gets a knock which dislodged diaphragm. But in any case as Karl says a stack needs to breathe ie. let air out as well as in (eg. when warm air in stack expands, and to relieve pressure ahead of water flows from branches) so it is placed above roof where smell should not be a problem. It also vents the sewer. AAVs can be fitted in the living space (as long as no-one hits them while boxing in ….)
     
    Last edited: Aug 11, 2018
  9. johnduffell

    johnduffell Member

    You can have as many aav as you like but you also need ventilation of positive pressure on your system. Aav won't let air out (on purpose), so it'll come out in your bathroom instead. The air needs to be able to come out as every time something goes down the drain the same amount of air need to escape. If it can't get out further downstream due to falls then it will come out your trap!
     
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