Weak flush on close coupled cistern

[bitstream7]

I have a close coupled Shires WC and the flush is really weak, such that it often needs several attempts to clear. Also, after flushing, sometime the water continues to flow through the cistern, stopping it from filling up. Can anyone give me a clue as to what's wrong. thanks Simon

[Andrew Mawson]

The piston that you raise by flushing (to start a syphon) is acually a disc of rather weak polythene trapped between a smaller pair of rigid disks, and after a few years they fatigue and fail. Cost literally pennies from a Plumbers merchant and if the job goes smoothly takes 30 mins to fix

AWEM

[mackem]

Did the flush ever work properly or has it always been like this?

[Ian Stirling]

Any thick polythene works well as a replacement. Cut out a disk to match the original one (plus a hair). You may as well do two or three, and stick them in the top of the cistern.

[Zipadee Doodar]

Used to have a similar problem in last house, - it never was any good. When I complained to the supplier, I was told that it conformed to British Standard test xxxxx - a toilet has to flush away 8 ozs of sawdust in one flush. I pointed out that in fact, although I am British, I do not tend to deposit significant quantities of sawdust. The occasional log perhaps.......

[bitstream7]

I bought the house about 8 months ago and it has always been this way, though I think it's got worse recently.

[mackem]

I can think of three reasons why the flush is weak:

1) As an earlier poster said, the diaphragm in the syphon may need replacing. 2) There is not enough water in the cistern to give a good flush - this could be remedied by adjusting the ballcock or filling mechanism to increase the level of water in the cistern. 3) If the cistern is several years old, it may have been originally fitted with a syphon that delivers 9 litres per flush. If, subsequently, the original syphon was replaced with a later version - say within the last two years - it is probably a 6 litre per flush version to comply with recent ( 2001 ) water saving regulations. Replacement syphons can usually be varied to give either 6, 7 or 9 litres of flush. There are probably three holes in the side of the piston/diaphragm chamber, arranged in a vertical line. If the top hole is open, the flush will be 6 litres. (The other two holes will be plugged with push-in plastic plugs.) If the middle hole only is open, the flush will be 7 litres. If the bottom hole only is open, the flush will be 9 litres.

With regard to water draining into the bowl between flushes; what is the depth of water in the cistern when this starts? One possibility is that the syphon is simply overflowing because the water level has been set too high in an attempt to improve the flush. Recent syphons have a built in overflow. Does the cistern have a separate overflow eg a pipe coming from the top or bottom left hand side?