AAV near WC pan

[robgul]

I have discovered that the flexible connector from the WC pan to the soil pipe does not have all the "fins" pushed in and is weeping - that's easy to fix - but I'm wondering if I can address another issue at the same time while I have all the cabinetry off.

There does not appear to be any venting to the WC/basin wastes which causes the shower trap to pull and then smell of drains. The whole shower room is boxed in and tiled - the soil pipe is dificult to locate although it does drop down through the downstairs cloakroom (although not obviously directly below the shower room) I can't find any eveidence of any sort of vent in the soil pipework (not through the roof, not in the loft)

My question is whether the layout (not to scale - flexible from the pan is about 45cm) in the very rough drawing would work to create a vent stop the shower trap smells. The back face of the pan is against a cabinet with all pipework concealed.

The plan would be to use an extension connector to add a short length of soil pipe to the existing 2" or so sticking through the wall - that short length of pipe to have an AAV fitted in a boss strap - and then a new (shorter) flexible from the pan.

AAV would be this one FloPlast AF32W Air Admittance Valve - https://www.NoLinkingToThis/p/floplast-af32w-air-admittance-valve/42968

Does this seem realistic? I have seen a McAlpine soil pipe/pan connector with a boss for an AAV but the clearance around the spigot in the concealed pipework pan isn't big enough.

All guidance and advice appreciated.

 

[SimonG]

What about an anti vac trap on the basin?

Where does the soil pipe go after stud wall?

Checked that theres not a blockage in the soil pipes anywhere?

 

[robgul]

What about an anti vac trap on the basin?

Where does the soil pipe go after stud wall?

Checked that theres not a blockage in the soil pipes anywhere?

Thanks for the response.

No idea where it goes - it must turn 90 degrees right through the stud (probably with an entry boss for the basin that's to the left of the WC) and then another 90 degrees behind a stud wall - collecting the shower waste along the way - then down to pick up the downstairs cloakroom WC. It's all completely tiled in.
I'm certain there's no blockage - it all points to the lack of vent causing the WC flush to pull the shower trap (that's a very shallow "cup" type ) - the shower tray is only about 2cm above the floor level.
The shower room is partly in a dormer and partly in the catslide roof beside the dormer.

There's no space to install an AAV on the basin - that's all boxed in very tightly too.

Would my concept as the drawing work to vent?

 

[WC1]

There's no space to install an AAV on the basin - that's all boxed in very tightly too.

Would my concept as the drawing work to vent?

An anti vac trap is not really an aav, its a tiny 1 inch by 1 inch aav on a standard trap.

https://www.NoLinkingToThis/p/mcalpine-antisyphon-bottle-trap-white-40mm/20226

 

[robgul]

An anti vac trap is not really an aav, its a tiny 1 inch by 1 inch aav on a standard trap.

https://www.NoLinkingToThis/p/mcalpine-antisyphon-bottle-trap-white-40mm/20226

It's venting the main soil pipe (as the WC flushes) that seems to be the cause of the shower trap pulling - not the basin.

Back to my original question and drawing . . . is that realistic?