Air Admittance valve

[Infidel]

Hi first post on this very helpfull site,
I had a soil stack running through the corner of my bathroom up through the roof space to outside.
My question is after cutting it down is there a minimum height that the air admittance valve needs to be ,I thought I read or heard somewhere that it should be above the level of any overflows (in this case it would be the sink)
Or does it not matter.
Thanks

 

[Newboy]

I think it's 2' above the overspill level (rim of the basin) - but you may have to have an open vent pipe - check with your local building control as you are making chnges to the soil stack

 

[Softus]

My question is after cutting it down is there a minimum height that the air admittance valve needs to be

I think you've acted hastily by removing a vent. Apart from not being a sensible thing to do, it's illegal without LABC approval.

An AAV is not a substitute for a roof-level vent.

 

[giblets]

As softus said - AAV's are only permitted on a secondary stack. The main vent stack must be of the open-open-above-roof-level type.

T'would be interested to know why the o/p cut the stack down.

 

[Infidel]

T'would be interested to know why the o/p cut the stack down.

[/code]

Long and very annoying story, smell in one corner of kitchen internal soil pipe and no concrete lintel or seal over the exit hole in the cavity wall resulting in a crushed and broken pottery bend thus a build up.
I had to renew old grey plastic soil and thought I may be able to get away without messing about on the roof as well as the footings and getting space for a corner unit. It's no problem I would have had to renew any way as old grey pipe very brittle.
Thanks for the info.