"Tim W" wrote in message
...
I have a 4m 110 soil pipe running from a centre bathroom under the floor to
a chamber outside. The next chamber along (top end of drains) is open
vented correctly.

In the bathroom, I will be connecting the sink into the toilet pipe.

Bog+sink into 110mm pipe. It clearly needs an air valve but I'd like to
check a couple of things:

Might I get away with a 50mm jobbie, like:

http://www.screwfix.com/prods/42968/

(I'm not worried about being "by the book", just whether it's likely to
work).

Otherwise if I have to use a 110mm version, does it need to be installed
above the flood level (so above the bog rim I suppose) or can it be
installed lower? The 50mm one above suggests 100mm above pipes and below
flood level.

It will be plugging into the top of one of these:

http://www.screwfix.com/prods/12454

Bog goes in the side port and the sink goes into one of the small side
bosses.

Sorry if this is dumb - never used an AAV before...

Fit a HepVo trap on the basin. A dry trap that si also an AAV. Simple.
http://www.bes.co.uk do them, available in most pro plumbing places.