I have always been told that it is better to vent toilets at roof level rather than use a dergo valuve, could you please advise if this is the case as I would perfer to vent a toilt on a project that I am working on with an in line vent but the buiding surveyour is recommending an external air intake valuve. I would appreciate another opinion.

lesley Stevens, March 2010

you can't just stick durgo valves where you want it
depends on the system layout and other vents.

external open vent is always better.

hi-spec plumbing & heating (essex), March 2010