"Ed Sirett" wrote in message
...
On Mon, 23 Apr 2007 14:43:40 +0100, TheScullster wrote:

Hi all

Just puzzled by the shape of my 1970s cistern.
I am re-furbing a downstairs toilet and noticed that the existing cistern
has a kind of curved cut-out in the back at the top left hand side.
This can be clearly seen in the picture below:

http://home.freeuk.com/thesculls/Cistern-Plan.JPG

There is no corresponding protrusion in the lid to cover this.

Anyone got any idea what the purpose of this profile might be?


I have assumed that these recesses were to allow air to enter the cistern
during flushing. On some models the lid fits pretty well and without this
opening the flush could be seriously reduced by the partial vacuum during
flushing.

I have no idea what the cutout is for but wouldn't the air enter through
the overflow pipe when flushing and exhaust again when filling as it does
on plastic cisterns with screw down lids?

Tony

--
Ed Sirett - Property maintainer and registered gas fitter.
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