Air vent

[truemanufan]

I have just seen an air vent from a waste stack terminating into a roof space? Whats that all about? It comes away from the wall and then back into the roof?

 

[Barry98]

sounds diy boof to me , can you get a pic ?

 

[mountainman]

Could be a durgo AAV and the installer put it there for maintenance purposes.

 

[Paulus]

It's so the warm, smelly vapours will keep pipes in the loft free from frost on cold winter nights.

 

[truemanufan]

Unfortunately no pic as I seen this whilst I was in the train back from town. Will look out for it next time