DIYbanter - View Single Post

wrote:

Sorry for my lack of knowledge but how can I tell if is an air admittance
valve !
Does this mean that the gas will escape into the loft and is this dangers
and healthy !

Other way. Air can be drawn from the loft, but not the reverse. Stops
loo flushing siphoning the waste traps.

They are one way flap valves.

Thanks