IMPROVED SIPHONIC ROOF DRAIN AND NEW USE IN A SIPHONIC ROOF DRAIN SYSTEM

摘要

Siphonic roof drain for draining rainwater under subatmospheric pressure, which siphonic roof drain comprises at least one drain bottom (2) and an air valve (3), whereby the drain bottom (2) is provided with an overflow edge (4) corresponding to the highest edge of the installed drain bottom (2), characterised in that the air valve (3) is made hat-shaped and comprises a bottom edge (8) situated outside the overflow edge (4) when installed and whereby this bottom edge (8) is situated lower than the bottom side of the air valve (3) at the overflow edge (4).