Air Admittance Valve height

[sting-stiz]

I am getting different advice from plumbers on fitting a toilet in a bathroom that originally contained just a basin and bath. The stack is internal , it comes into the garage then bends into the bathroom. It cannot go straight up (so can externally vent) as it would go into the bedroom over the garage and there is a window right next to the wall so I cant even box it in.
The bathroom is not big enough to vent the pipe up as its only just long enough for the bath.
The floplast AAV (AV110 & AF110) specifications (see below) says it is A1 complient and can be fitted under the spill level but must be 20cm higher than the highest wet entry into the stack. Does this mean I can fit it under the bath as long as its 20cm higher than the lowest entry into the stack (toilet) even though the basin overflow will be higher?.

[b]Description : A1 approved in accordance with BS EN 12380, can be installed below the flood level of connected appliances. FloPlast are the first company in the world to be awarded the Kitemark for Air Admittance Valves in accordance with BS EN 12380:2002, licence number KM512474.
[/b]
Stiz.

[rosebery]

And you'll probably get more conflicting advice here as well!

Its unclear from your post whether its an existing soil stack or a new one. If its existing it must already be vented somewhere? If new you'll be having Building Regulations approval of course. So I suggest you ask your building inspector what he wants to see in order to be happy to sign it all off.

Cheers

[sting-stiz]

Hi its an old internal stack (30+ years old). It originally had a basin and bath waste going into it. It terminated under the bath , just under the shoulder or back edge of the bath, the plumber removed the top bit which seemed to be a cap but could have been a durgo valve. The plan was to install a toilet and he said a toilet pan connector with a integral AAV valve would be fitted which raised my suspicions as I've never heard of one.

Note the old toilet is seperate at the back of the house with a normal vent via the roof but this is nowhere near the front 'bathroom'.