Soil Stack Vent

[JoeMar]

Hi All

I am currently planning my new bathroom and needs some advice regarding the soil stack vent. Please see image

The current soil stack is in black. i want to use a concealed cistern when replacing the toilet which will be sited exactly where the current toilet is. as you can see the soil stack will be in the way therefore i am thinking of re-routing it - green line.

My question is, when re-routing the vent pipe, do i need to stick with 4'' pipe or can i use a smaller one. Im also thinking of putting an aav in the loft rather than an open vent - any thoughts?

thanks[/img]

 

[JoeMar]

...ok, after reading a few posts on here, the AAV is not an option as there is not other open vent.

As the pipe is running internally hence hoarfrost is not really an issue, is it ok to use a smaller diameter pipe for the vent?

 

[muggles]

If you can find it then you can use 3" pipe but beware, it's often more expensive than 4" as it's quite rare that it's used

 

[RHS]

If your not the last house in your road a AAV should not be any trouble, you don't need to take it to high either just high enough that you don't get "back wash "

 

[muggles]

That too, you *theoretically* only need a vent on every fifth house, certainly if it's a terrace

 

[JoeMar]

thanks RHS and Muggles