Potterton Profile 100e on/off constantly

[Steelmasons]

Possibly the boiler stat is short cycling due to system up to temp , the original poster has already stated the house is too hot 24 hours a day.

VERY rare for the end switch to stick on with the motor at rest.

 

[ianmcd]

you havent read the post Steel, the OP was advised to disconnect the grey wires to the zone valves and this solved the problem

 

[Steelmasons]

you havent read the post Steel, the OP was advised to disconnect the grey wires to the zone valves and this solved the problem

Well of course isolating the grey core at faulty CH valve will disconnect power to boiler , my bet being when hot water is called for the radiators will also get hot.

Then again if both grey cores are terminated at each respective brown core at valve then this will also cause these symptoms as when the grey core is removed the motor will de-energise and close the valve , so in the case of the OP I would be checking that each grey core is terminated at perm live and not brown motor core.