Electric fan heater or gas central heating?

[FaithLoveandGrace]

Hi all,

I'm wondering which is cheaper - using an electric fan heater to heat one room, or using the gas central heating? We live in a small flat but the living room is by far the largest. DP thinks it's cheaper to just use the fan heater in that room but I'm not so sure.

You can probably find calculators online. Fan heaters cost a bomb to run! Do you not have valves on the radiators, to turn down the ones in little-used rooms?