WC Pan Connector with a 32mm AAV

Discussion in 'Plumbers' Talk' started by Taylor93, Jun 10, 2019.

  1. Taylor93

    Taylor93 New Member

    Hi All,

    I have a mid 60's Ex-Council house with an issue with a waste smell coming from the downstairs toilet.

    Spoken to Severn Trent, they have confirmed that the house is on the "end of a run", The WC is on the end of this run of Sewer pipe, with no soil stack. The Water level keeps dropping as the sewer sucks the water from the Toilets trap down into the sewer. So it needs an AAV.

    The Pan connector is a 90 degree elbow, directly into the ground, with no other waste connections (Sink takes a different path to another part of the sewer)

    To avoid digging up the floor and moving the Soil pipe (although this would make it easier to fit a new close coupled toilet as its quite far out from the wall, 12" or so) could I use one of these:


    Then attach a 32mm AAV at the end of a short run of pipe (to ensure AAV is above max water level).

    If my understanding of EN 12056-2:2000 is correct, then a single toilet with a 6L Flush capacity works out at a Waste Water flow rate of 0.5 x sqrt (2.0) = approx 0.791 L/Second.

    Single toilet, so that means Total Flow rate (Qtot) = 0.791 L/second.

    So surely the 32mm AAV Would work sufficiently for this case? or is there another regulation i am missing, which prohibits the use of a 32/40mm AAV on a 110mm Soil Pipe.

  2. KIAB

    KIAB Super Member

    If toilet is on outside wall , easier to core 110mm hole through wall & put in stack pipe outside,much easier than digging up floor,at a previous place I put in a stub stack with AAV on outside wall for downstairs toilet,hardest job was digging down to clay pipe in garden.:)
  3. Taylor93

    Taylor93 New Member

    I dont think thats really an option either.

    the WC is in the "front corner" of the house. One wall has the Cold water feed/stop cock, the other wall (which it is closest to) has the Electrical supply to the property, i dont want to get the DNO to move my supply cable and have a lovely looking soil pipe next to the front door! :D

    The only place the toilet can really go, is where it currently is, and it sits almost directly ontop of the soil pipe. So unless my "work around" above, is acceptable (maybe a building regs issue?) then i may well have to dig up the floor :(
  4. NoOhmToGoTo

    NoOhmToGoTo Active Member

    What have you got to lose? Give it a go. It's your house, you're not signing anything off and it'll most likely work.
    Have a customer with a similar flaky set up and it's worked for years. (I didn't install it btw!)
  5. Taylor93

    Taylor93 New Member

    Long term i would like to rent the house out, so would like to know that my work does comply with the correct standards etc.

    Id just like to make sure that i am doing a good job thats all.

    I appreciate that the best solution would be to dig out the soil pipe and fit a proper waste stack etc, but its just too awkward there with the stock cock being right next to it etc. its a bit close for comfort.

    my current thoughts are however, it has been like this for getting on 50-60 years (previous owner did mention it) so adding a 32mm AAV might help and it will certainly be better than the current setup i.e. no ventilation; its just whether it is deemed a bodge, or the "right way" to do it.
  6. Joe the Plumber

    Joe the Plumber Screwfix Select

    I'm sure you'll be okay with the AAV (and if it doesn't work, you can always take it out and put a bung in the fitting), but if you're right at the end of a run of sewer pipe, I'd check to see if anyone has somehow blanked off the nearest vent pipe, as I'd assume there must be some on it further down the line.

    There shouldn't be a permanent vacuum in the pipe allowing atmospheric pressure to break the water trap in your pan.
    WillyEckerslike likes this.
  7. Jimbo

    Jimbo Screwfix Select

  8. rogerk101

    rogerk101 Screwfix Select

    I have a 40mm AAV as the only vent for the 100mm soil pipes in my house in France. It serves 2 bathrooms and the kitchen. It has worked perfectly for the last 28 years.
    I'm a 32mm AAV would be OK, but why not try a 40mm one?
    BTW, the 100mm soil runs at least 30m to the septic tank, with no 'breather's along the way. All rodding points are screw-top with gaskets.

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