DIY Doctor UK DIY Forums

Hi all - hope someone can clarify some points for me.

I am currently installing the plumbing for three bathroom in an extended house. Each bathroom has its own soil pipe connection which lead to the same main drain which is combined waste and rainwater.

This is what i plan to do -

Downstairs loo - main question here relates to need/or not for a durgo on soil pipe as it doesnt vent externally.

Main bathroom - first floor room plan to fit durgo again as not external venting. Shower will also drain into this soil pipe do i need additional air admittance valve on 40mm pipe from shower trap?

En-suite - first floor, soil pipe vents externally - bossed into this soil pipe will be bath waste from main bathroom and basin waste from main batroom and en suite. Do i need to fit any air admittance valves on 32 and 40 mm pipework?

Hope this makes some sense and any advice is greatly appreciated.

Cheers.

Generally only one vent is required per property unless the soil pipe run is excessively long. This should be situated at the end of the underground run.

Usually no other AAV's are required, but if some of the small bore pipe runs are over three metres or they have combined connections then it is a good idea to use an anti vac trap as this prevents the water seal from being syphoned away or the trap from gurgling.

Thanks for he reply plumbbob.

I have done away with the durgo in the downstairs toilet.

As for the AAV`s on the 32/40mm pipe work you said to perhaps fit an antivac trap?? Is this the same as fitting an AAV on to the 32/40mm run before it is bossed into the soil pipe. If so does it matter where on the 32/40mm run it goes?

Thanks again.

mathew1971 wrote:As for the AAV`s on the 32/40mm pipe work you said to perhaps fit an antivac trap?? Is this the same as fitting an AAV on to the 32/40mm run before it is bossed into the soil pipe. If so does it matter where on the 32/40mm run it goes?

The important point is that all AAV's to work efficiently need to be fitted as near as possible to the beginning of the run. This prevents water being syphoned from a trap which breaks the seal allowing gasses to escape.

http://www.awin1.com/awclick.php?mid=1228&id=61071&p=http://www.screwfix.com/prods/15739/Plumbing/Wastes-and-Traps/AntiVac-Bottle-Trap-32mm

Other styles are available.