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Is it cheaper to turn off the central heating and use electric heaters instead?

Radiator v electric heater

Following on from the last blog ‘How much do your household appliances cost to run?’ a reader asks: Is it cheaper to use an electric fan heater or central heating?

According to The Energy Saving Trust, in a typical household over half of the energy bill is spent on heating the home and hot water. So, how can we save on these costs?

Unit cost for electricity v gas

The comparable prices under the current energy price cap are as follows (rounded up):

Electricity Unit rate: 34p/kWh Standing charge: 46p/day

Gas Unit rate: 10p/kWh Standing charge: 29p/day

On first impressions, electricity costs 3 times as much per kilowatt hour as gas.

Running cost: electric heater v gas central heating

A 2000W or 2kW fan heater in one room will cost 68p an hour to run (2kW x 34p x 1 hour). If you just use it for an hour or even a shorter period of time, then you won't run up big bills, but if you are running it for, say 9 hours, that will cost a maximum of £6.12.

A modern combi boiler for heating water and central heating tends to range from 24kW to 40kW (you can find out by looking at the details on it, or by finding its model description and looking that up online).

For a home containing three bedrooms and up to 10 radiators, a typical combi boiler would be 24kW. To run this for one hour would cost a maximum of £2.40. For 9 hours that would be a maximum of £21.60.

You can see that a fan heater in one room would definitely be cheaper than centrally heating a 3 bedroom house which would cost over three and a half times more, but the electric heater will only heat up a small space and the heat will quickly dissipate in a cold house.

If you were to put electric fan heaters in all rooms of a typical 3 bed house with 6 rooms (three bedrooms, a bathroom, kitchen, and living room), the cost for one hour would be £4.08 and £36.72 for 9 hours – 70% more expensive than the central heating.

Of course, you could turn the electric heater on and off with immediate effect when the room is in use or not, but the overall heating effect would not be as warming as central heating.

These are rough estimates and the actual cost depends on lots of different factors: The reason we say maximum is because many appliances, especially heating appliances, do not run at full capacity the whole time, so this is a good rough rule of thumb.

If you have gas and electric smart meters you should be able to use these to work out exactly how much your gas combi boiler is costing you to run in a typical day and compare that to using an electric fan heater.

If you don’t have smart meters then you could take two gas meter readings 24 hours apart and use the calculations to work out how much a typical day costs. See how much you would save by turning off radiators in rooms you don’t use, or turning down the thermostat by a few degrees.

So, which is best?

Well, it seems to be horses for courses.

In a smaller home it might be better to heat the whole house whereas in a large home where some rooms are not used, it may be better to heat individual rooms either with central heating or an electric fan. If you are there for a short period of time the electric fan gives quicker immediate heat.

If you can stand going from a warm room to a cold room, then heating just the rooms you are going to use could save a lot of cash. From a health perspective, it is better to err on the side of caution when you are considering heating just one room if it means you have to go from a warm room to a cold room, especially for the elderly or young children.

If you are going to heat just one room, minimise heat losses to the unheated spaces by keeping doors closed, using draught excluders to block the gap between the door and floor, and closing curtains. The same applies of course for all rooms if you are using central heating.

If you prefer your warm comfort, limit the heating of the whole house with central heating to just the time you need it. For example, have the central heating come on for an hour before you get up in the morning so that you can enjoy the benefit while you get ready to go to work. Then have it come back on an hour before returning from work and go off just before bedtime.

You can further cut costs by setting the thermostat to 18 or 19 degrees; the boiler should run to keep the house at that temperature and once it has reached it, then it will not run constantly. You can also cut costs by adjusting the boiler flow temperature, and turning down radiators in less-used rooms.


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