Enter the number of kWh required for heating in the white cell
below. A year's central heating for a small flat in England, Wales or Ireland
may be about 5000, for a 2 bed home 7000, 3 bed home 10000, 4 bed home 18000.
Heating one room (occasional) 1200, (full) 3000. Overall System efficiency is
not just the appliance
efficiency and will vary very substantially.