FYI, a gas engineer told me that it is best to keep all rads (if they have thermostats) to about 3-4 rather than whacked right up to 6. I find that my thermostat on the wall of the coolish hall, set at 19C, makes all rooms pleasantly warm. If it is really cold I leave the heating on at about 15C all day and it stays warm. (PS I switched to Bulb. If you want to join and get ?50 of credit (which, if you ask them, they will put into your debit card account) drop me a line with an email address.)