Oooooh - never used a HepVo before...
Might have to have a look into one of those - I like new toys
It's a waterless valve ( trap ) that will allow air to be drawn into the system but seals to prevent foul smells coming back into the room and is available in both 32 and 40mm along with bent and straight adapters . It can be used in any situation where you would use a normal trap
