Space Heater makes Clicking Noise: 2 Common Reasons for the Popping

Your space heater makes a clicking noise and you’re not sure where it’s coming from and whether your heater is broken?

I’ve had this myself: I was comfortably sitting on my couch, with my infrared heater keeping my feet warm. It was really comfortable and I totally concentrated on the book. All of a sudden, there was a loud clicking noise. It was a quick clicking sound, just like the sound you often hear right after turning on an oven or an air conditioner.

But what is that noise and where does it come from?

In this article, we cover the two most common reasons why space heaters make clicking sounds.

Additionally, you’ll learn how to hear the difference between a properly working space heater and a faulty one. After reading, you’ll know exactly, whether the clicking, crackling or popping sound is a good or bad one.

So, let’s start.

Why does your space heater make a clicking noise?

Even though all space heaters have different designs and work in different ways, there’s one thing, nearly all of them have in common: Sometimes they produce clicking noises.

So, it doesn’t really matter which kind of heater you have. The following two reasons fit every heater type.

Expanding surface material makes a clicking noise

I’ve had this so many times. And it’s not limited to space heaters. Lots of devices that produce heat, click at some point.


I own a small, portable oven with a metal surface. Every other day I bake something with it: A few buns for breakfast or a pizza for dinner.

After about 5 minutes of shutting the oven off, there’s a sudden, crashing “booom”-sound.

I jump every single time.

And this sound occurs each time I use the oven. The same thing happens with space heaters.

But where does it come from? After some time, I realized that it must be the surface material of the oven:

When it heats up, the metallic surface experiences internal tension, because metals expand when they heat up.

The metallic surface of the space heater releases the tension in sudden bursts, which you perceive as the loud clicking noise.

Tension can release during heat up and during cool down, depending on the design of your heater.

My space heater always clicks when it heats up (sometimes it’s also a popping or crackling noise), whereas my oven always clicks when it cools down. I believe it’s the surface design and shape that is the biggest impacting factor when your heater clicks.

In the space heater domain, mostly oil-filled radiators produce these clicking sounds, because of their metal surface.

But the clicking does not occur on metal surface heaters only:

I’ve had the clicking noise with my plastic infrared heater as well – even though the surface is not metallic.

There seem to be internal metal elements that that contract, expand, tense up and click.


The clicking noise of a space heater is not dangerous at all. It’s just a sudden release of tension – nothing to worry about.

Your space heater uses a two-point control

Most space heaters have built-in controls to produce the right temperature and protect them from overheating (Oh, I love that topic, I’m a control engineer).
Such controls can work in a smooth way:

The higher the temperature gets, the lower the power we give the space heater – this effectively lowers the heat and prevents overheating. If the temperature starts dropping again, the control automatically slowly increases the power. That’s how a thermostat works.

But oftentimes in space heaters controls work not in a smooth, but a harsh way:
When the temperature exceeds a threshold, the control turns the power off. And when the temperature drops below a lower threshold, the power turns back on again.

We call such an on-off control a two-point control (or two setpoint control). Two-point controls are very common in space heaters (instead of of a “smooth” control), because:

  1. It is cheaper to develop.
  2. It is safer & easier to shut big amounts of current on and off than to limit them.

Because the engineers designing the space heater need to switch on and off big currents, the best electric switch to do so is a so-called relay.

A relay is an electric switch that mechanically switches connections. Each time it’s switched on or off, a piece of metal bumps onto another piece of metal – that’s where the clicking noise in your space heater comes from.

how a space heater relay looks like
This is what a relay looks like.

I liked this explanation:

“The clicking sound is the arm moving between the contact points when the coil is energized or switched off”

msplines – electronics expert

Therefore, the clicking noise is not dangerous at all. It’s actually a healthy sign of a properly functioning temperature control.

Are there space heaters that don’t make a clicking noise?

There probably are space heaters that don’t make any clicking noises. However, I never had one.

If I had to get a space heater that never makes a clicking noise, I’d look out for infrared heaters – possibly with a wooden surface. Wood is flexible and doesn’t click.

Also, I’d look out for space heaters in a higher price range. It is likely that more expensive space heaters use better thermostats than the simple on-off controls that are often used in cheaper space heaters.

But generally, even the safest space heaters sometimes make a click. As long as you know it’s safe and your space heater is working properly, it shouldn’t bother you.

Is noise an indicator of failure – Is your space heater broken?

But what if you’re not sure about the noise that comes from your space heater?

As we now know, the clicking noise is not dangerous at all – as long as it’s just clicking noise.

Screeching noises in space heaters

In contrast, a sharp screeching and squealing noise could indicate failure.

In my experience of working with and designing electronic circuits, screeching noises always have to do with improper power conversion in space heaters.

When you plug your space heater in the wall outlet, a transformer first transforms the voltage to a lower level.

Squealing or buzzing noises nearly always come from a broken transformer.

When a transformer doesn’t work properly and you plug it in the outlet, it receives high voltage and current it can’t handle. The transformer starts vibrating aggressively and a screeching noise comes out.

A screeching or squealing noise is a sign that you should replace your space heater.

how a transformer in a space heater looks like
The metal layers of a transformer vibrate and produce noise.

What about humming noise?

“The alternation current that flows through an electrical transformer’s coils has a magnetic effect on its iron core. It causes the core to expand and contract, resulting in a humming sound.”

D&F Liquidators

A humming noise is a healthy sound that doesn’t indicate any defects. It often occurs when infrared lamps heat up, or when transformers work properly.

The noise of a space heater fan is obviously fine as well – fans always make noise.

What to do if the noise annoys you?

If your space heater makes annoying noises, I’d advise getting a new heater.

Generally, the most silent heaters are infrared heaters or oil-filled radiators.

While both of them can make a clicking noise here and there, they only do them seldom. While they’re heating they don’t make any continuous noises, because they don’t have any noise-producing parts like built-in fans.

In contrast, electric heaters with built-in fans are the loudest types of heaters. Oftentimes, you can already tell by the reviews online whether a space heater is quiet or not.

The reviews are a good starting point you can refer to before getting a new, quiet space heater.

Conclusion – Space Heater makes clicking noise: Why?

Answer: Your space heater makes a clicking noise because the surface materials are expanding and creating tension when they heat up. At some point, the tension releases and creates a clicking noise. After that, tension starts building up again, and after a few minutes, there will be another click.

The second possible reason is that your space heater controls the temperature using a so-called two-setpoint control, where the space heater turns on and off over and over to retain the same temperature level. Switching on and off is done using an electric switch – a so-called relay – that produces the clicking noise.

The clicking noise is not harmful at all.

If your space heater produces unhealthy-sounding screeching or squealing noises, it is likely that the internal power conversion (the transformer) doesn’t work properly.

Such noises usually indicate, that your space heater is broken and that you should get a new one.

I hope, you could get some insights into how space heaters produce clicking noises and you can now tell whether your space heater noise is “good” or “bad”.

If you’re interested in learning more about space heaters, check out the other articles here.

Attributions: title image by Aaron Yoo (CC BY-ND 2.0)