Defies the laws of physics???

[Beyond the blue]

Good morning
Two years ago I installed a toilet cistern with the internals shown in the pictures. For the last couple of days the cistern has started filing up very slowly occasionally kicking in to full speed. I have stripped it down a little to find the fault and noticed that the Grey floating valve shown in the pic with the three components is not rising enough to allow full flow, yet when I open the cold tap on the nearby basin (effectively lowering the pressure to the cistern) the valve pops up and allows full flow again. How can this be?? The less pressure to the valve the more the valve rises, my mains pressure is between 3-4 bar, I'm stumped with this one. Can anyone offer any help please.

 

[ShaunCorbs]

Normal needs the fill valve changing yours is a siamp you can swap or upgrade I like fluid master personally

 

[Chuck]

The less pressure to the valve the more the valve rises, my mains pressure is between 3-4 bar, I'm stumped with this one. Can anyone offer any help please.

IMO, it's not worth wasting time trying to fix/diagnose problems with faulty float valves. Replace it and move on. My go to replacement is the Fluidmaster Pro (with a brass shank).

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I'm fairly sure it's not the laws of physics that are being broken. Maybe the mains pressure is distorting the plastic just enough to cause something to stick?

 

[SimonG]

Its a siamp, its gash. Replace with something decent.