Have just had a problem with boiler and BG came out yesterday and identified that a valve which diverts the heating to hot water, when required, was sticking. Cleaned it and boiler working again now. When he was testing the boiler he had to fiddle with what i think was the frost thermostat. Since he went the boiler has been on continuously from 13:00 until 03:00 when I couldnt stand it any longer and turned it off. At 02:00 I went around the house turning all the radiators thermo valves to the lowest setting. I know it has been freezing cold all through this period and the bolier is in the garage but I am sure that previously in cold conditions the boiler would come on periodically to protect itself from frost and not continuosly. Does anybody think that the BG repair has changed something or can you suggest what might be wrong, or is the boiler behaving as you would expect?