IF one of your tanks in the loft is overflowing, it may be down to float valve failure. It could be just the washer needs replacing but for £5 you can change the whole valve. You should be able to do this yourself as it is fairly easy.
You will need to purchase a new (part 2) float valve BS1212.
Firstly turn your cold water off at the mains which will cut supply to tank.
If you have a part 2 valve already it's easier to split the valve in the middle at the big nut and just swap the moving parts. (You can also do the same with a part 1 valve too)
Alternatively, to change the whole valve, undo the bent tap connector and then unscrew the old valve off the cistern and discard. Fit the new one on by reversing taking one off. Turn water back on and test for leaks.
SETTING THE WATER LEVEL
For the large cistern- supplying the cylinder…………
Adjust the float by sliding it up or down the arm via the screw (or you may need to bend the metal arm) so that the water cuts off 3 inches below overflow pipe.
For the smaller F & E cistern- supplying the heating system……….
Adjust float to cut off water when the water level is 100 mm deep to allow for water expansion.
