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Electric Heaters: Convection vs Radiant        
Electric Heaters: Convection vs Radiant

What with winter truly upon us, many of you will be looking for additional ways to heat your home. A popular choice will be to supplement your central heating with the use of electric heaters. But did you know that not only is using electricity an extremely expensive way to heat your home, but your choice of heater can have a dramatic effect on your bills!

 

The two main options for electric heaters are convection and radiant heaters. Convection heaters look like smaller radiators and radiant heaters tend to be more upright and have a glowing front heating panel.

 

They differ greatly in the amount of energy used; convection heaters will typically be 1, 2 or 3 kW, whereas radiant heaters will be 0.4,0.6 or 0.8 kW. What this means in real terms is that radiant heaters use 50% - 60% less electricity to provide the same amount of perceived warmth.

 

Perceived warmth is the amount of heat you feel you are getting. Radiant heaters can be directed where the heat is needed, such as someone sitting on a sofa, meaning the rest of the room isn’t needlessly heated. Convection heaters need to heat the surrounding room in order to make you feel the same warmth i.e. they are much more inefficient.

 

Let’s compare the cost of using a convection vs a radiant heater for 3 hours a day for a 100-day winter. I will assume the unit cost of electricity is around 20p/kWh (similar to what someone using a pre-payment meter would pay).

 

Convection heater: 3kW * (3hours/day * 100 days) = 900 kWh, costing £180/year!

 

Radiant heater: 0.8kW * (3hours/day * 100 days) = 240kWh, costing £48/year!

 

What’s more, you are much less likely to leave radiant heaters on when you leave the room because the glow is a visual reminder to switch it off. Whereas convection heaters often have little or no external indication they are on, so can be left on by accident, wasting even more money!

 

The humble hot water bottle is even more efficient than radiant heaters, and they have much more versatile uses e.g. used to sleep with. A hot water bottle would typically use 3kW to fill up and boil, and easily provides warmth for a few hours. The saving comes because this energy is only used for a fraction of the time (to boil the kettle) than a heater would be on for…

 

Hot water bottle: 3kW * (0.1hours/day * 100 days) = 3kWh, costing approx. £6/year!   

 

So using a hot water bottle uses approx. 0.5% of the energy required that a convection heater uses for the same amount of time. That's a huge saving of £174 per year!!

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