AAV (Durgo valve) position

Above the trap as far as I'm aware

 

Check the MI's, it varys.

 

Some can be really low.

 

the rule is,,it must be above the flood level,, which is the highest point the water can come into the room, usually the wash hand basin, if you don't have a basin then the toilet pan rim level, which is roughly where Phils picture is.

 

This came up recently and a manufacturer said theirs could be below the flood level, can't remember the details and not a plumber.

 

oh right, so the new rule now is, google for the new dessign AAV and take note that not all plumbers own a 'current affairs' book,