Intermittent drip ball valve in cws

[Ashtara]

We had a new ball valve fitted to the cws in the loft (old one was making noises)
Since then I have noticed I can hear a whooshing sound from
The pipes when water has been used and it is filling. I believe this is normal?

What I have noticed however is that the ball valve seems to intermittently take forever to shut off and drips for ages - can be for hours.

I have lifted it whilst it is dripping and it does shut off so it’s working as such.

I have pushed the valve down and can get it to stop dripping this way too.

I have checked first thing in the morning and it isn’t dripping (waited 5 mins and nothing dropped) so don’t think I have a leak

My question is, is this normal or have I got a dodgy ball valve or something else?

 

[HERTS P&D]

Normal.

Andy

 

[bernardgreen]

The float ball valve will open very slightly when the pressure in the water supply increases and will then close when the water level in the tank has risen by just a few millimetres.

The valve closes when the force exerted by the floating ball on one side of the washer in the valve is greater than the force exerted by the water pressure from the mains water on the other side of the washer.

The force exerted by the ball depends on how much of the ball is below the water line. If the mains water pressure increases then there has to be more of the ball under water to produce the increased force necessary to oppose the increased force from the water supply