We have a gas central heating system and we have set the thermostat to come on at different temperatures during the day. Generally between 7.00 and 22.00 it is set between 19 to 22 centigrade. From 22.00 it is set to be 10 degrees. During the day we can see that the settings work ok but we during the night it isn't clear. Most of the radiators have the same make valves as the thermostat. There are 2 older ones that do not (bathroom and hall). During the night these 2 radiators get hot and we dont know why. Surely if the thermostat is set to low 10 degrees then the boiler shouldn't be producing hot water anyway? Can someone shed some light on this?