How Do Electric Heaters Work? A Crash Course

Last updated: February 2023 

How many of us can say that they know exactly how the tech in our home works? The inner workings of our computers, smartphones and even our heating systems often remain a blissful mystery, and unless something goes wrong, we rarely have reason to look inside. But if you’re the curious type, you might be wondering ‘how do electric heaters actually work?’. Well, in short electric heaters work by using a length of resistive wire that heats up as electrons pass through the metal. It sounds complicated but, as we’re about to explain, it’s actually very simple.

Resistance: the essence of electric heating

Before we get started, we’ve first got to cover a little bit of basic physics that’s key to electrical engineering: resistance.

Resistance occurs when an electrical current flows through a conductor (e.g., a length metal wire), and the electrons collide with particles in the metal, slowing down the current. It’s like trying to move down a crowded corridor – if there’s more people, you’ll have to spend more effort and energy trying to get where you need to go. And so, if a wire has high resistance, it generates a greater amount of heat as a result. In some electronics, this warmth is often an unwanted by-product (just think of how much wasted heat old incandescent bulbs create!) but for an electric heating system, this is absolutely vital.

Virtually all electric heating systems use resistive heating – also known as Joule heating – in order to create warmth. It doesn’t matter whether it’s an electric radiator, a panel heater or a storage heater, they all use a resistive wire heating element to warm a room. The only real difference is the size and layout of the wiring. It could be very long and stretched out across an entire floor space, as per an underfloor heating system, or it could be as small and as compact as the heating element for a towel rail.

Does that mean all electric heaters are the same?

Though most electric heating systems use Joule heating to create warmth, how this technology is applied can differ significantly. After all, if they were the same, there wouldn’t be such a broad range of heating options available. There are a lot of ways resistive heating is used, so let’s take a look at some of the most common methods used by electric heaters.

Convection heaters

Appliances that create heat via convection will use heating elements that are exposed so that they can have maximum contact with the air. These elements might be fixed at the base of the appliance, as in the case of panel heaters, or they might be used in tandem with a fan to actively pull in cold air across the heated wire.

The benefit of exposed heating elements is that the surrounding air is heated up very quickly, so if you need warmth in a pinch, these appliances can be especially useful. However, since all of this warmth is transferred to the air, heat can be easily lost through draughts, so their use tends to be geared towards occasional, on-demand heating only.

Electric radiators

In electric radiators, the heating element is fully enclosed within the appliance, so unlike a convection heater, you can’t look inside and see it ‘at work’. The reason they’re enclosed is so that the heat from the element can be transferred to the body of the appliance and conducted out into the room.

Electric radiators are able to heat rooms using a mixture of convection and radiation because of how their bodies are designed. Their aluminium or steel bodies effectively conduct heat from the elements out into the room, while the fins on their housings maximise contact with the air to warm spaces swiftly.

Infrared panels & underfloor heating

Both of these heating systems use fully enclosed heating elements, though they’re laid out entirely differently to products like electric radiators. Infrared panels use a length of fine wire that is spread out across the surface of the appliance in a large ‘S’ shaped pattern, whereas underfloor heating uses your floor space as the heated area and has wires placed evenly all across the room.

These types of heaters work on the basis of ‘heating a lot of wire a little’ to produce a gentle warmth over a larger surface area. The result of this is that they produce a type of mellow radiant heat that’s exceptionally comfortable for users. It does, however, take much longer to bring rooms up to temperature from cold, so for best results, these systems should be left to run at a lower setting rather than switching them off altogether.

Oil-filled radiators & towel rails

In oil-filled products like some radiators and electric towel rails, the resistive element is very compact so that it can be slotted into one of the side struts of the heater. The appliance body is then filled with oil so that the element is completely submerged. When the element heats up, it transfers warmth to the surrounding fluid, which then starts to flow around the body of the appliance in a liquid convection cycle. The heat spreads across the surface and then is emitted out into the room.

Oil-filled electric radiators

Electric towel rails

Every type of electric heater supplies warmth either through convection, radiation or both, but it’s important to know the difference. Check out this clip to learn more.


One simple method, hundreds of options to choose from

If you’ve been wondering “how do electric heaters work” all this time, hopefully you now have a better understanding of what makes them tick. Resistive heating is simple but very effective and it can be used in a variety of ways to achieve different types of comfort. If you’re not sure which heating method is best for you, browse our site for more inspiration, or call us direct on 0330 300 4444 and let our heating experts help you find the perfect solution for your project.

Key learnings

  • Virtually all electric heating systems use resistive heating – also known as Joule heating – in order to create warmth.
  • Though most electric heating systems use Joule heating to create warmth, how this technology is applied can differ significantly.
  • Convection heaters heat though 100% convection, whilst infrared panels heat through 100% radiation.
  • Electric radiators and towel rails use a combination of both - combining fast heat-up and slow cooldown times to give you the best of both worlds.