I have an 800W oil filled radiator. Can anyone tell me if it is cheaper to leave it on all the time (it has a thermostat) or to switch it on and off during the day?
This business about whether it is more efficient to leave heating sources on all day or not really only applies to boilers. These are not as efficient below normal working temperature so can end up using more fuel if constantly switching on / off. With normal tariff electricity, every Watt of electricity consumed gets converted into heat with no waste (motors for driving fan heaters excepted) so ther's no point in leaving it on if you don't feel the need for the heat.