FloPlast External/Internal Air Admittance Valve 110mm

This is a top quality air admittance valve made by FloPlast, colour Grey.
Model AX110G.
It can be used externally.
It is a useful device only allowing air into a soil pipe system when a vacuum is formed but will not allow air out if positive pressure is present.
Most authorities allow them indoors when it is not possible to fit a conventional vent when one is needed to maintain water in sink, shower or bath traps, for example, when toilets are flushed creating negative pressure in a system.
There are a number of videos on YouTube which explain how they work and the benefits of them in certain circumstances.
This model will Push-fit into a 110mm pipe or be glued with solvent into an 82mm one.
A new one can be over £50. Read more