I have a gravity fed CH and HW system, approx 12 years old. We are now not using the CH part (summer??) but notice when the timer comes on to heat the water (twice a day) all the radiators get hot aswell just as though the CH was also selected. The system is run by a single timer unit with seperate programming for water and heating. The CH programme is definately set to off. Does anybody have a clue where I should start my investigations?
Cheers
John