Soil Pipe Design with Air Admittance Valve

[barney12]

Hi Hope someone can help.
We are re-designing our onsuite and want to move the location of the bath and toilet. We currently have a vertical stack with an air admittance valve thats aprox 1.5m high into the room. The toilet is connected by a branch and pan connector.
With the new design we would need to move the toilet but also where the valve is, I've tried to draw it below:

Will this be OK? Provided I've got the correct fall so water doesn't travel the wrong way it seems logically OK? Or does a air valve always have to be at the top of a vertical stack.

Many many thanks in advance.

Rob

 

[Bas]

Rob, your diagram seems fine. The AAV must be above the cistern height and the run from the WC to the vertcal stack musnt be more than 6m for a 4" pipe. Ensure the fall is correct and that the T to the WC is swept toward the down pipe

 

[croydoncorgi]

The point of an air admittance valve is that it lets air IN. It does NOT prevent water leaking OUT. So it must be well above the highest 'flood line'. (ISTR the standard is 300mm above) In other words and in this case, above the top edge of the WC pan.

Also, an AAV does NOT substitute for an open vent. I THINK it's still the reg that there must be AT LEAST one open vent per building.

But then - what do I know - i'm a gasman!

 

[barney12]

Thanks guys thats great.
We don't have any open vents in our barn (Two soil stacks) although the conversion was 3 years ago now so perhaps the regs have changed?
Having said that the AAV in the main bathroom (Different stack) is at the same level as the cistern and sink ???
I guess this means that if we ever had a blockage then the water would come out of the top of the stack rather than the sink or loo? eeeeek!

Apparently though the plumber who did the work was an alchoholic! So perhaps building control missed it!

Rob

 

[doitall]

Regs haven't change.

The head of the drain has to be vented to atmosphere.

We've covered this before, without a vent you could end up with explosive gases in the building.

This particularly important with cess pits etc.

With terrace houses and shared drains you could vent every 8 house or was it 7 ?

 

[Bas]

I bet he was a plumber before he was an alchoholic.....