Why Does My Space Heater Keep Turning Off?


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When people want to warm up an office or small room in the house, space heaters are a common go-to. Many people find when using a space heater for long durations of time, it starts to turn itself off repeatedly. But why?  

Space Heaters turn off when they overheat. Overheating can be caused by a dirty air filter restricting airflow into the heater. Without a constant stream of cool air, the elements within the heater will become too hot, and the automatic shut-off will be initiated for safety.  

Overheating isn’t the only reason your space heater might be continuously turning itself off, though. The rest of this article will explain other reasons your space heater could be turned off, as well as how to fix these issues.   

Why Space Heaters Overheat and Turn Off  

How Space Heaters Work  

A typical space heater is powered by electricity. The electricity flows through the metal or ceramic heating element, which causes it to become hot. This heat is then transferred into the air – sometimes with an internal fan – making small spaces warmer. These two processes are called Joule heating and convection.   

Why Your Space Heater Is Overheating   

The front of your space heater will have an air filter. If your heater is turning on and off repeatedly, a blocked air filter is likely the cause. You can recognize that an air filter is clogged because it gives off a very obvious burning smell.  

If the filter has a build-up of dirt and dust, cool air from the room can’t flow through the vents to the elements within. You’ll notice the elements inside the heater glow a brighter red or orange than usual because they’re not cooling in the same way.  

The excess heat will trigger the heater’s built-in safety shut off. By immediately switching the heater back on, there’s no time for the elements to cool down, and therefore it will automatically turn off again straight away.  

To continue using your space heater, you need to leave it to cool for a while and clean the air filter.  

How to Clean a Space Heater Air Filter 

Depending on what space heater you’re using, cleaning the air filter should be simple and easy:  

  1. Disconnect the heater from the power and leave it to cool down completely. 
  2. Wipe down the heater with a duster or microfiber cloth to remove loose dust. 
  3. Spray the filter with compressed air to dislodge dirt and grime build-up. 
  4. Using the brush attachment on your vacuum, you can gently suck up dirt from small crevices.  
  5. Wipe off any excess dust from the front and back of the heater before turning it back on.  

This is how I clean the air filter on my space heater. However, there may be other heaters that require you to remove the filter first. Once it’s out, you can continue with step 3.

Other Reasons Your Space Heater Keeps Turning Off 

There are, of course, other reasons your space heater might be turning off. For example, if you’ve only recently bought it, there shouldn’t be a build-up of dust. So what else might be the cause?  

Faulty or Weak Power Supply 

Space heaters take quite a lot of power. According to Qlabe, an average space heater uses 1500 Watts (1.5kilowatts) to efficiently heat a space. So, one reason your heater is turning off is the incorrect amount of power coming from your sockets.  

Alternatively, the power supply might be faulty. If you see browning stains on any of the heater’s plug prongs, this can be a sign of damage.  

I would always recommend contacting an electrician to take a look at faulty sockets, rather than trying to investigate yourself. However, you can try the heater in a different socket to see if it works any better. 

Your Home’s Circuit Is Tripping

If you’re trying to use more than one space heater at a time, it might be tripping the main circuit. Locate your home’s circuit box to check if any of the switches have been triggered. If so, switch it back on and try the heater again. If the issue persists, it may be due to a power overload. You should try to use fewer heaters at the same time or spread them across different circuits (usually different floors or rooms are connected to different circuits). 

The Space Heater Is Faulty

The issue might have nothing to do with your usage, but actually, the product itself is faulty. Space heaters often come with a warranty, and if yours is within that warranty, you can take it back for an exchange or refund.  

You could take back your space heater for the same type or try a different brand to see if the issue persists.  

Space Heater Safety: Stats and Tips

Using a space heater comes with its risks. Fires, burns, and carbon monoxide poisoning are all dangers of using space heaters within your home.  

Space Heater Safety: Statistics

According to the Department of Energy, each year, space heaters are the cause of:  

When used safely, space heaters can work perfectly fine, but it’s important to know how to use them in your home safely and efficiently.  

Space Heater Safety: Tips  

Check for Safety Features

Space Heaters for home use will have automatic safety features triggered in the event of overheating or if the heater falls over. For example, I recommend the Lasko 7542000 Space Heater because it has built-in overheating protection, as well as an exterior cooler, which means its body can be touched safely even when on high. 

Safety features to look out for:  

  • Any-tip security  
  • Automatic shut off 
  • Safety certification 
  • Timers 

Ensure There’s Space Around the Heater

Keep your heater 3 feet away from furniture, curtains, or walls to prevent the chances of a fire. It’s very tempting to place a space heater under a desk when it’s cold to keep your legs warm, but trying to save enough space around the heater so air can easily flow into it. 

Place the Heater on a Flat Surface

While it might sound simple, make sure the heater is on a flat surface – and preferably on the floor. Heat rises anyway so that the room might feel warmer faster too. 

Final Thoughts 

While it’s easy to think a space heater should heat a room for hours and hours, they’ve only ever been made for short term use. They should be used to accompany central heating, rather than instead of. Space heaters can be really dangerous when not used properly, which is why most have a built-in shut off for when they start to overheat.  

If your space heater keeps turning off, leave it to cool down before using it again.

Steve Rajeckas

Steve Rajeckas is an HVAC hobbyist with an avid interest in learning innovative ways to keep rooms, buildings, and everything else at the optimal temperature. When he's not working on new posts for Temperature Master, he can be found reading books or exploring the outdoors.

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