I want to cap my waste stack with an air admittance valve, so I can run my bathroom flue through the old pipe out through the roof.
I'm not clear what height I can cap it at though. It runs though a utility room containing the boiler, and the stack is joined by a toilet waste and a sink waste, close to the ground. Can I cap it
a) Whereever I like (preferably about as low as p b) Above the drain outlet of the boiler c) Somewhere else
I gather it's supposed to be above the "flood level" of the room, but I'm not clear what that is, particularly given that this is a first floor flat...
Ben