Reconfiguring 2 X toilet and 1 X bath outlets

[Tff]

Hi
I need to move my existing external toilet and bath outlets due to having a rear extension built and they foul the roofline.
After advice / opinions on my preferred option which I have included as a sketch.
My main concern is:
1, If I'll need air admittance valves and where they need to be positioned - if I do need them.
2, And whether it would ok / advisable to connect the bath outlet to the proposed toilet outlet....
Just to confirm the existing soil stack is vented correctly above roof level.

Any help / advice / criticism gratefully received.
Cheers Tony

 

[Madrab]

As long as the distances aren't too long then you would get away with what you propose for the toilets without supplementary venting, given the stack is vented. If anything then a 40mm AAV on the furthest run might be needed, if there was any syphoning seen.

If the waste pipe from the bath needs to be fitted to the soil pipe the ideally it would connect into to the top of it, not bossed into the side of it, that would be asking for trouble with possible backflow or syphoning. You'd really want to take the bath the same route as the soil pipe and joint to the stack separately.

 

[Tff]

Thanks for your help / advise Madrab - much appreciated
Another option I thought of was this pan connector with a 40mm boss:
https://www.drainagesuperstore.co.uk/product/bent-90-degree-pan-connector-with-boss-inlet.html
And have this installed on the ensuite WC and run the bath into.
But unsure if these are suitable for horizontal installation? Anyone any experience of them able to comment?

 

[lostinthelight]

If the bath and toilet were on the same floor the bath would need to on stilts for the waste to run into that boss .

 

[Tff]

Good point well made!!

 

[Madrab]

If you want to avoid problems, run it separately into the stack, shouldn't be that difficult to route it alongside the soil pipe. It is extra work but certainly worth it.

 

[dilalio]

Can visualise wc forcing sh¡t into Bath in proposed setup.