For a little while now we've been hearing at random a loud sucking noise coming from out kitchen sink. This sink is a 1.5 bowl with a washing machine attached.
The noise happens at random and appears to be when the downstairs neighbors are in and is nothing to do with our appliances or the sink itself. After some looking I could see the sink trap and the surrounding pipes had no air admittance valve, so I have fitted a p-trap with a air valve on it hoping this would prevent the vacuum which appears to be coming from the soil stack from reaching the water in the p-trap. The fitted trap can be seen below
Technical drawing here http://mcalpineplumbing.com/sites/default/files/uploads/drawings/SA10V.pdf
This appears to haven failed as last night during the nightly washing up the sink started making that noise. I was draining no water at the time. I use a spoon handle to press the air valve up and a lot of stinky air came rushing out.
We are in a 20 year old top floor apartment which is using Durgo/Air Admittance Valve on the soil stacks as these cannot be seen from the roof. To me it sounds like the AAV is failing on that soil stack and the pressure from the neighbors is causing the noise. It appears to be strong enough to skip the valve on the p-trap completely and suck the air through the p-trap water.
I wonder if this sounded right to anyone.