Why Heating Wires Are Coiled?

by Kevin Smith Author

You may have noticed that the heating wires, or elements, of some of your devices are coiled. Maybe you’ve noticed the red-hot coils in your toaster or on your stove top. Maybe you had to order replacement heating coils for your defunct electric heater.

The principle behind the coiled heating element is straight forward. Like most engineering designs, it’s about fitting as much of something in as little a space as possible. Though, to best understand the process, you need to understand how heating elements get hot in the first place.

Heating with Resistance

Heating elements are material that produce heat when electricity is run through it. Heating elements can be anything that meet this requirement. A light bulb is a good example. Electric current passes through the filament in the light bulb and the light bulb produces heat.

The reason this happens is that the electricity flowing through the current encounters resistance. When the electricity encounters this resistance, the current is interrupted and some of that electricity is converted into heat. If you have a material that has a high-resistance, much of the current is interrupted and more of the electricity is converted into heat. The lower the resistance, the less heat will be released.

There is a balance that needs to be maintained. A heating element that has too much resistance can staunch the current, which would lead to less electricity flowing through the element. If this occurred, there would be less heat given off because the electricity being resisted would be less because the current was less. In other words, to have an efficient heating element, you need to have high enough resistance to convert electricity to heat, but not enough resistance to hamper the current.

The Practical Element and Design

In the lightbulb case mentioned above, the design of the filament is not efficient in producing heat. While a lightbulb can be very hot, it doesn’t heat up the air in the room. To produce more heat like you would find in a heater, the heating element requires a lot more energy, more resistance, and more length.

Heating coils are made to withstand a lot of voltage with minimum breakdown. You can increase the current to the heating element and more heat will naturally be produced. The heating coils are often made of an alloy called Nichrome. The nickel-based alloy has a high resistance. As mentioned before, this resistance allows much of the electricity to be converted into heat. Additionally, Nichrome heating coils will also react rather than oxidize. This means that the heating coils will burn out less often.

The coiled shape design comes down to a matter of spatial engineering. The coiling of a wire means that you can fit a longer wire in the same area as you would if it was a straight wire. The coiled heating element will have a higher resistance than a straight wire because it is longer. The heating coil can produce more heat with the same amount of current.

Coiling the heating element is a relatively simple design that makes a huge difference in efficiency. Understanding how electricity flows and how to balance the current with the resistance has enabled us to have near instant heat. All we have to do is flick a switch. Next time you’re looking for replacement heating coils, consider the ingenuity of their simple design.