On Fri, 25 Apr 2008 16:34:26 +0100, Tim Downie wrote:

I think they let air into the syphon. If you look at page 18 (or 15) of
the report on http://www.watersave.uk.net/Links/Dualflushreport.pdf you
can see what I assume is an air admittance tube fitted to the top of the
syphon.

Ah yes, it says the device has 3 tubes (not visible in photo) which let air
into the syphon at various levels. Similar to the Mecon device. THey
speculate that much of the device's savings was because users tended to
leave the flush volume control on the middle setting, in which case a
brick in the cistern would be just as effective.

--
John Stumbles

Fundamentalist agnostic