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Room heaters

Room heaters are used to heat a small space and are normally portable or fitted to a wall. Most room heaters use gas or electricity.

Room heaters are convenient appliances that provide focused and localised heat which is particularly suitable in a room for people that are elderly, ill or with limited mobility. But they can be expensive.

[NB if you're looking for our information on night storage heaters, click here.]

Room heaters consume a lot of gas or electricity, and if used over a long period of time are likely to cost a lot more than a central heating system.

Ideally, room heaters should only be used as a secondary or supplementary source of heat. Even then, you should use the right heater for the space you want to heat, and carefully control the temperature and the time you have the heater on. Heaters that have these controls are often cheaper to run.

What kind of room heater?

When you’re deciding on what room heater to use, consider first what purpose you want it to serve.

1) Heating a whole room for a few hours or more
For this, you should use a convector heater. These work by warming the air immediately next to them which then naturally circulates relatively evenly around the room. Convector heaters are a good choice if you need a supplementary heating source to warm up a room for a few hours at a time. They take a little longer to work, but this type of heater can be easily controlled with a timer and thermostat, so you don’t overheat the room and you save money.

2) Heating a room for a short period of time 
For a quick blast of warmth, or for more directional heating, you should use radiant heaters. These work quickly and are useful if you want to warm up only part of a room for a short period, as they tend to heat only what is in front of them. Unlike convector heaters, they don’t achieve an even level of heat throughout the room, so often don’t bring the same level of comfort over time. They rarely have thermostats or timers, which can make their running costs more expensive over long periods.

Electric room heaters

Electric heaters are all considered to be 100% efficient, because they turn all the electricity they use into heat, but this does not mean they are cheap to run. To calculate the running cost you need to look at the power rating of the heater, shown in kilowatts (kW). The higher the power rating the more heat will be produced, but also the cost will be proportionally higher.

The table below shows typical running costs for a range of electric room heaters. Costs are for heaters used on the highest setting, and which are producing heat for the whole hour.. However, heaters with a thermostat will automatically turn off when the required room temperature is reached, meaning in reality the cost will be lower over several hours.‚Äč

PictureHeaterHeatsourceTypical power ratingRunning cost per hour (Single-rate
Running cost per hour (Economy 7 night)*Running cost per hour (Economy 7 day)*
1Bar fireradiant2 kW 29p15p34p
2Convector heater convector2 kW 29p15p34p
3Oil-filled radiatorconvector1.5 kW22p11p26p
4Fan heaterradiant2 kW37p8p43p
5Halogen heaterradiant1.2 kW18p9p20p

* Running costs assumptions: Single-rate meter, 14.6p/kWh; Economy 7 (night),  7.2p/kWh; Economy 7 (day), 17.0p/kWh To calculate this yourself times the heat output of your electric heater by your electric kWh unit cost.

Heat parade 1 (electric) 1) radiant bar fire, 2) convector heater, 3) oil-filled radiator, 4) fan heater, 5) halogen heater.

Electric room heaters are all expensive to run and not appropriate as a main heat source. Chose a type of heater depending on how you intend to heat the room, because otherwise you may have a high running cost but not feel an increase in comfort from the heat. Halogen heaters tend to be the cheapest radiant heaters as they have a low power rating (but also produce less heat), while oil-filled radiators are often the cheapest convector heater because there is a thermostat to control the temperature.

In general, if you have to use an electric room heater, use it only when necessary and consider the following:

  • Use a timer if it has one, if not, you can buy a timeswitch for the plug from a hardware shop.
  • A thermostat will reduce running costs, though how much it reduces costs by depends on lots of factors, such as room size, insulation levels and making sure the thermostat is not turned up too high.
  • If you are on Economy 7, avoid using heaters for long periods within the peak hours if you can. It’s better to use night storage heaters that are charged at night.

Gas room heaters

Gas heaters are different to electric heaters in their efficiency, as not all the gas is converted into heat output into the room (some is lost as exhaust gases, moisture and the creation of light). However main gas is around three times cheaper than electricity, meaning that  the running cost is often comparable’

Gas heaters can be run on mains gas, or LPG (liquid petroleum gas) also known as bottled gas. If you are considering purchasing a gas heater you will need to check current safety regulations as some fixed heaters require flues or chimneys, to ventilate combustion gases and moisture out the home. Portable gas heaters don’t need flues, however you still need to make sure the room is well ventilated. Otherwise there is a risk from carbon monoxide, while the water vapour gas heaters produce can cause condensation and if not ventilated can lead to damp and mould problems.

Heat parade 2 (gas): 6) traditional gas fires, 7) convector heaters, 8) open gas fire, 9) bottled-gas heater. 

Gas heaters are sold with a heat output rating and an efficiency rating, which should be looked at in conjunction with each other. Heat output is an indication of how much heat will be provided into the room. If you look at two heaters with the same heat output, the heater with a higher efficiency will be cheaper to run than the heater with the lower efficiency. This is because it will use less gas to provide the same amount of heat.

The table below calculates the running cost for heaters using mains gas and LPG, based on the average heat output and efficiency rating of various heaters. Actual costs will vary, but what’s important is how they compare with each other. These are based on the heaters being on full power for the hour, without a form of thermostatic control.

The table below shows typical running costs for a range of gas room heaters. Again, the actual costs will vary as gas prices change, but what's important is how they compare with each other.

PictureHeaterHeat sourceTypical outputAverage efficiencyRunning cost per hour (mains gas)*Running cost per hour (LPG)*
6Radiant gas fireradiant5 kW60%35p84p
7Gas convector 
convector3 kW60%21p50p
8Open decorative 
gas fire 
radiant2.5 kW28%38p90p
9Closed decorative 
gas fire 
radiant4 kW60%28p67p
10Bottled gas 
radiant4 kW92%n/a73p

* Based on 4.2 kWh for mains gas and on Oct 2018 Sutherland tables calculations for LPG. To calculate this yourself  (output ÷ efficiency) x 100. Multiply the result by your gas kWh unit cost.

If you are on mains gas, then gas central heating is usually the best way to heat your home (modern boilers are around 90% efficient). Use the thermostatic valves on your radiators, if you have them, to adjust the level of heat you want in each room. For more information, download our gas central heating controls factsheet.

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