Toilet Flush Weird Issue

Bellycaster

Thanks for that @pumkin I'm sure your right, I can get the cover plate to move a couple of mm either way but it doesn't seem to want to come off. I daren't be too heavy handed with it, try to prize it off.

I wouldn't know what to do with the float valve anyway or even recognise what's what in the damn thing. I might need to watch some YouTube vids. Gladly, it's not an emergency.

Jimbro66

The replies here make sense but they do assume an old-style ball valve and lever where the washer can be replaced. The Geberit cistern is likely to have a modern type fill valve that has an integral float, not a ball and lever. With this type it is not a simple washer replacement and not really a DIY job. I know this because I have just recently had to deal with a defective fill valve of this type. I got a reliable plumber friend to look at it and he advised that because of its problems and the effects of limescale build-up it was best to replace the fill valve rather than attempt to strip it down and service it. I took his advice. It works fine now. 

ICBM

LastMantra said:

A ball floats the same and works the valve the same on 6 inches of water as it does on 8 inches of water 

You’re totally missing what happens with a leaking washer, when the water continues to rise past the point the valve would otherwise shut off.

The depth of water *below* the ball is irrelevant. What matters is how deeply the ball is held *in* the water by coming up against the stop of the valve closing.

LastMantra said:

It's the ball that determines when the tank is "full".

No, it isn’t. “Full” is determined by the point where the force on the washer from the ball exceeds the force on it from the water supply pressure, by enough to deform the soft washer material into a watertight seal. If the washer has become hardened with age, a little more force difference is required to make a good seal.

LastMantra said:

But if it worked it worked.

Which is why I’m explaining *why* it works .

LastMantra

  can't be bothered trying to explain any more.

pumkin

Oh the conversation is still going .... you must be bored .... I guess I must be too .... but to clear a few things up ... this is not a normal ball cock type float valve you’re talking about , in which case @LastMantra would in theory be right .... this is what they call a fluid master type valve that relies on incoming water pressure to keep it closed once the cistern is full .... not sure exactly how it works but I’m sure the information is out there .... one solution would be to fit a non return valve on the feed to the cistern, this will negate any pressure drops elsewhere. Just replacing the washer in the valve may also sort it as they get clogged up and may not work properly ... especially if you’ve got hard water .