if one radiator is warm when heating is off or one thing works other does not it is the diverter valve or so called motorised valve which with wear and tear then gets stuck one way or the other it is easy to fit just open the lid where the clocks are and there are two screws above undo them the whole thing drops forward then you can see the valve which is a black sealed case the left handside as you look towards the boiler undo the electrics(PLUG only fits in the unit oneway you connot make mistake) look carefully you will see a pin using a long srewdriver prise it off and the diverter valve comes off replace same as taking off. part costs approx £37 inclusive of vat but it is best to phone around i hope this will help all u people out there
kal, October 2008
