How to Fix Ideal Standard Dual Flush Toilet? (Not Enough Water in Cistern)

SteveVy

grumbler said:

If the float is in the top position, I don't think you can rise the level any more.

However, there seem to be some 'stop' on the road  - both in one of your pictures above and in this photo below:

https://helpfulcolin.com/repairing-toilet-silent-fill-valve/ -  there are some instructions there ("Adjusting My Cistern’s Water Level"), but they are no different from what was said above.

Thanks for this...any idea then why 3 out of 4 toilets are not filling correctly? As I previously said the toilet that is filing correctly has the adjusting screw for the valve float only 1/2 way tightened...

theoretica

When the cisterns stop filling the black float should have risen up a bit raising the white lever.  In the one which fills more is the float more under water or is the top of the float higher above the bottom of the cistern?

Jeepers_Creepers

By 'sprue' I meant anything plastic sticking out from the thread that would stop it turning - I could see something like this in your original photo, but Grumbler's far clearer post explains it better. But you reckon the whole screw rod disappears in to the float?

These 'floats' are well-designed - they don't have bottoms to them, so cannot leak in water like the old 'ball'cocks.

This is now a mystery! I can only suggest you try what Grumbler has said - are these inlet valves all the same size? Are the cisterns all the same size? Ie - are they the correct valves for these cisterns?! Measure the max top height of the float for this and a 'good' cistern, and also the comparative water levels.

And are the floats behaving as they should - drop down easily with the water level, and then rise smoothly as it fills - with a sudden water 'shut-off' at the end?