Inline /Tee air admittance valve to prevent siphonage

[bigdrew]

I am just fitting my bathroom and have the bath and sink running off the same 40mm waste pipe. (Not possible to run the separately)

The pipe runs Bath >> Sink >> Soil pipe.

I have this bath waste / trap http://www.screwfix.com/p/mcalpine-bottle-bath-trap-white-40mm/21158

and I am worried about it being siphoned when the sink is drained (Is that likely?)

I was wondering about fitting a air admittance T such as this: http://www.toolstation.com/shop/Plu...3136/McAlpine+VP3+Air+Admittance+Valve/p56476

in between the bath and sink.

Does that sound sensible and should it reduce any risk of the bath trap being siphoned?

 

[Newboy]

The risk is more that emptying the bath will pull the basin trap.

Fit an basin trap with an incorporated AAV

 

[SandyLyon]

Trap with AAV or HepVo valve on basin.

 

[bigdrew]

Thanks both. AAV basin trap brought.