My mother in law has a new bungalow (3 years old) with an electric only system. It's controlled using an SM1 controller which I've set to come on once a day between 6.30am and 10pm. She sets the thermostat so the heating comes on whenever the temp drops below the thermostst set point. However, she rang at 12.30pm last night to say that that the radiators were hot and the light on the thermostat was on. Is it the SM1 that needs replacing? Could the thermostat override the SM1 somehow and force the heating on outside of the controller's on/off times?
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