Water tank problem

[Paul]

Every few days my cold water tank starts to over flow.
I have replaced the ball cock valve once.
I have to turn off the water and run the tank down a bit then it's OK after that.
This happens on a morning around 6 or 7 am.
I have tried turning down the water supply to the tank but it still over flowing randomly.
any ideas how to stop this!
Paul

[WHL]

The Ball cock should stop the flow when it fills up, sounds like, there's your problem, try bending the rod down a bit, so stopping the flow earlier.

[trevnhil]

Or.. the trouble could be around the washer inside the ball valve. If it has grit in it or is perished that will allow water to leak past it even when closed

[Uncle D]

Seems strange that it only over flows every few days as opposed to overflowing all the timel

[Paphos Pete]

I once came across exactly this scenario when asked to look at a friends system. The header tank occasionally ran out of the overflow despite the ballcock being reasonably new and in good order. The problem was with the indirect immersion.

The immersion tank was vented into the cold water header tank. Occasionally, the immersion heater thermostat got stuck and effectively allowed the immersion to almost boil. The escaping condensate drained into the cold water tank raising the level, causing it to overflow.

Might be worth checking. The main symptom was the hot water was excessively hot.

Pete

[bmwx5]

I had ball cock and both solar panels replaced and have not used the immersion heater for over 2 yrs but have had over flow occasionally when the water gets extremely hot on some days.

[ludlowboy]

Choose a brass ball valve, ensure after fitting the ‘tank full’ level is about 3” (75mm) below the valve, bend the arm to adjust. Sand/grit is a common cause, low usage does not allow enough flow to flush any dirt out. (I used to be a plumber, but I’m ok now!)