Sizing a heater to the room
Allow about 1 kilowatt (kW) for every 10 square metres of floor in a room with average insulation and a standard ceiling, as a rough guide. That puts a bathroom or box room at up to 1 kW, a bedroom or home office at 1.5 to 2 kW and a living room at 2 to 3 kW. An older, draughty or high-ceilinged room needs more, and a new, well insulated one less.
Quick heat, steady heat or stored heat
Every electric heater turns all the electricity it uses into heat, so the difference is how and when it gives that heat out. Panel heaters, convectors and ceramic heaters warm the air quickly and suit rooms used at set times, oil filled radiators warm up slowly but give a steady, quiet heat, and storage heaters store heat overnight on off peak electricity and release it through the day. On a standard tariff, a timer and an accurate thermostat do most to cut running costs.
Plugs, wiring and bathrooms
Portable heaters plug into an ordinary 13 amp socket, while wiring a heater into the mains is a job for a qualified electrician, and storage heaters also need an off peak meter and their own circuit. In a bathroom, the heater needs the right IP (ingress protection) rating for its distance from the bath or shower. A 2 kW heater on full uses 2 units of electricity an hour, and oil filled radiators are sealed, so the oil never needs topping up.
