cold water tank

[condor66]

the cold water tank in the loft s dripping.After being out all day the water level goes up and drips out of the overflow. What do i need to donow do I need a new ballcock

[terence7556]

no the ballcock sits on top of the water and shuts off the flow of water coming in, exactly the same as the cistern in the loo
the problem is the inlet valve not stopping the water coming in. if you know how and can be bothered change the washers that are worn and not seating correctly or just change the inlet valve
good that your overflow is working correctly

[tezestwing]

Hi condor66 First of all you need a selection of suitable washers then to make sure you can isolate the mains water to the brass ballvalve then remove the split pin remove the ball arm hold the valve body in one pair of grips undo the cover of the front piston chamber then withdraw the piston then with the grips unscrew the two part piston replace the tiny rubber washer then put back as removed. If it is a plastic ballvalve turn off water as before then undo with fingers the large front nut that houses the flat diaphragm washer, replaced as found the correct way round and reassemble as found finger tight only HTH Tez