Central heating overflow

[northernchappy]

I noticed the overflow pipe was dripping in the morning and about an hour later it had stopped.
I tried testing the ballcock valve by pushi g it down and it returned ok.
I could only see one ballcock and not sure if there are two.

The central heating system is an indirect baxi bermuda.
In the loft, theres the green insulated copper tank with 3 plastic reservoir tanks.
It overflowed (dribbled/dripped) the once about a week ago and hasn't overflowed since.
So, is there a fault?
Thanks for any advice in advance

 

[terryplumb]

would need a lot more info than what you have given to really help, however if it is the overflow that is connected to the upper part of one of the cold water cisterns ,the first thing you need to establish is that the ball cock/float valve is closing fully when the water level reaches the required level .so ,by hand ,lift up the float arm and watch carefully to see if it still let's water pass, even a slow drip will over time overfill the cistern.it should close fully and no water should pass.