Phil L wrote:
Dave Plowman (News) wrote:
There's a cast iron drain vent on the front of my house - just above
an inspection cover - which has started to pong a bit sometimes. It's
a sort of horizontal grill on top of the pipe about 3 ft above ground
level. I assume there should be some form of valve in it since
there's no water flow to keep a u- bend full? And this has failed?

Dunno much about underground drains...

Is the cast iron vent like a soil stack?
is it against the wall?

If it is, then it seems that it's snapped off or been taken down in the past
and not replaced, it should be about 2ft past the gutter, to avoid pongs
coming through the bedroom windows.

If it's not then I've no idea what you're talking about, any chance of a
photo or a sketch?

I remember seeing the sort of thing Dave is describing as a child
living in London (Fulham - not a million miles from Dave). Definately
purpose designed rather than sawn off soil pipes. Look a little like
periscopes with a grill on the front.

I also assummed they were some sort of drain vent, but i've no idea how
they work/ed