water escape from vent pipe

[jgmplumbing]

Hello

Can someone help and advise me why water is escaping from a small vent pipe in the airing cupboard? Small vent pipe has a small screw down nut at the top of it?

 

[prs1]

new aav needed its supposed to just let air out needs replacing pal

 

[jgmplumbing]

Hello

Thanks for your reply.

Sorry but i'm new to plumbing, still training. Please specify what AAV is?

Thanks

 

[stevetheplumber]

automatic air valve screw the cap down temporarily

 

[jgmplumbing]

Thank You!