Immersion heater and overflow pipe help needed

[jameseast]

Hi all.
I have an immersion heater in my house, the overflow pipe outside has been running non stop?

There is a large cold water tank in loft and a smaller cold water tank above the immersion heater that i presume feeds the heater. It sounds like the cold water tank is constantly filling and the pipe outside is running for days.

I have managed to stop the flow by turning of the heater /the water and running the hot water for a few mins, would it be something to do with the thermostat - hence why its constantly heating water and having to overflow?
thanks in advance

 

[mikegas]

your ball valve needs replacing

 

[jameseast]

thanks for the quick reply, im fairly happy to have a go at this myself , but do both tanks have a ball valve or just the large main water tank in the loft? Is the outside overflow pipe connected to the main tank to prevent it from over filling or the small one above the immersion ?

thanks again

 

[mikegas]

dontknowitall explains it clearly in this thread http://www.ukplumbersforums.co.uk/i...-attic-ballcock-job-liverpool.html#post189869

 

[PlumbBobBob]

both tanks will have an overflow. you will have to ascertain which is overflowing to know which one to fix

 

[ecowarm]

Is the large tank filling and the small one overflowing?