# What is the difference between a resistor and a heating element?

As far as I know, a resistor and a heating element are the same thing. But one, the resistor, seems to limit the current in the circuit while the other, the heating element, draws more current and converts it to heat.

One wastes watts and the other doesn't, yet they are both resistors.

What is the difference between a resistor and a heating element?

• Resistor is an electronic component, which is "wasting watts" as heat as a side effect. Heating element is a component intended to "waste watts" as a primary function, but it acts as a resistor as a side effect. – Eugene Sh. May 1 '18 at 21:59
• It depends on the heating element and the resistor. Some heating elements (PTC) wouldn't be used as a current limiting resistor because of the high temperature coefficient. – Samuel May 1 '18 at 22:01
• somewhat related: Resistance of a light bulb – Nick Alexeev May 2 '18 at 1:24

They have most characteristics the same, but the OP is interested in the difference between them. Short answer: Thermal stability.

The major difference in characteristics between a resistor and a heating element is that resistors are designed from a material standpoint to have a low thermal resistance change. That is, resistors maintain as constant a resistance to current as possible throughout their operating range. Heating elements have no such requirement, so their resistance can and does vary a lot with current. For a lot of heating elements, its resistance will appear to be nearly a short at room temperature. As current goes through it and it heats up, its resistance increases.

A resistor and a heating element are indeed the same thing, just designed for different jobs. In a resistor, heat is generated as an undesired (but unavoidable) side effect, whereas in a heating element, the heat is exactly what it's supposed to do.

In fact, resistors can be used as heating elements! I've seen at least one ovenized oscillator (where a tiny oven is used to keep one component at a very specific temperature) that simply used a resistor as the heating element.

One difference that does exist, though, is that heating elements are generally made of materials that will work at higher temperatures. They're supposed to get hot, after all! Resistors usually aren't as heatproof.

• Was a nasty old dog house in the back yard of a home that I bought one time, and when I broke it up to take it out to the trash, I found a 100W ceramic power resistor wired up to a thermostat and an extension cord inside. – Solomon Slow May 1 '18 at 22:17
• Yup: Intent is the difference. – The Nate May 2 '18 at 13:21

A heating element is a resistor tuned to produce as much heat as possible when current is passing through it. When current passes through a resistor, there are losses defined as: $$P(Watt) = IR^2$$

Typically in a circuit, these losses are undesired and in portable electronics mean a loss of maximum battery life. So, in a heating element they are designed to produce as much heat per watt of loss in the resistor; in a conventional circuit, they are designed to have low of losses as possible.

• You can't "tune" the amount of heat per Watt that is dissipated by a resistor. A resistor (including a purpose-built electric heating element) always turns 100% of the dissipated energy into heat* – Solomon Slow May 1 '18 at 22:20
• *Of course, any hot object will subsequently radiate away some of its heat as light. Possibly including visible light if it gets hot enough. – Solomon Slow May 1 '18 at 22:21
• Resistors come in many shapes and sizes and have datasheets which rate the temperature it will reach with 'x' amount of current passing through it. No, you cant 'tune' the amount of power dissipated - but you can tune a resistor to more effectively radiate heat. Not all resistors with the same resistance and current passing through are going to reach the same temperature as your comment indicates. – user160063 May 1 '18 at 22:30
• @jameslarge but if that was true, wouldn't it cause batteries to lose the same amount of energy and discharge at the same rate regardless of the resistance in the circuit ? – soundslikefiziks May 2 '18 at 1:54
• @soundslikefiziks Do you understand circuits? – immibis May 2 '18 at 2:36