Which Heaters Are Safe to Leave On Overnight?

Ben Leonavicius
By Ben  • Updated:   March 27, 2024
Affiliate disclosure: When you buy a product via our links, we sometimes earn a referral fee. Learn more

If there’s anything more important than the comfort of you and your family, it’s your safety. And while a good space heater is a wonderful way to ensure your comfort in colder weather, it is totally natural to wonder if it is safe to use them.

One of the biggest questions people have is whether it is safe to leave them running unattended for a long time, or is safe to run a space heater overnight.

So let’s look at this important question in more depth.

Can You Leave a Space Heater Running Overnight?

Yes and no.

Older space heaters can be very dangerous to use unattended, day or night, and are to blame for lots and lots of fires in the home. They can overheat and become dangerously hot, can seriously burn you on contact, and can ignite various objects and materials nearby.

Space heaters – and especially older ones – can emit dangerous chemicals and other emissions, and are linked to carbon monoxide poisoning. 

Electrical overload and related problems can also be issues with space heaters, and older products in particular can shut down breakers, cause power outages and even contribute to electrical fires.

Modern electric space heaters, however, come with a host of safety features that make them safe to use unattended, and even to leave running overnight. These features include:

  • Overheat Protection – this is a vital feature, which ensures that if for whatever reason your space heater gets too hot it will immediately shut down. Overheating is dangerous, and a main reason why so many older space heaters were rightly connected to home fires, electrical overloads, and related problems.
  • Auto Shutdown if Tipped Over – nightlight or not, we can all be a little groggy during our late-night wanderings, and it is so comforting to know that if we, our children or even our nocturnally rambunctious pets knock over a running space heater it will simply turn itself off.
  • Cool Casings – not only can this keep your kids and pets safe, and you safe late at night when all is dark, but the stay-cool housings of most good new space heaters will also prevent fires or scorching – still, always keep your space heater well clear of everything, with plenty of space around it.
  • Thermostat Control – although overheat protection, mentioned just above, is actually more important for safety, an automatic thermostat is still somehow reassuring. The real benefit, though, is that it makes your space heater run more efficiently – when the desired temperature is reached, the heating element will turn off, and stay off until the temperature falls below a certain level. This means that running the space heater is also a lot safer for your wallet!
  • No Emission Designs – the best new space heaters are especially good at heating without releasing any gas, smoke, chemicals, or other harmful emissions, which of course is important day and night.

So the simple answer is that if you have an older space heater you should be very, very cautious, and probably should not leave it running overnight, or even leave it unattended during the day for extended periods. This is especially true if the heater does not have all of these modern safety features.

And even if you have a newer space heater, you should make sure it does indeed include this whole host of safety features. If so, and you take some basic precautions in mind (see below), there should be no problem at all in leaving your heater running overnight, or for long periods of time during the day.

What Space Heaters Are Safest to Use Overnight?

Even if almost all types of modern electric space heaters have most or all of these safety precautions built in, there are still three specific types of heaters that are especially safe to use unattended.

If you are considering purchasing a new space heater, I can’t recommend strongly enough that you get one of these three types, which are not only safer but more effective and efficient and cheaper to run than pretty much any others.

Infrared Heaters

Infrared heaters are among the safest to use since the heater element itself does not get that hot. They stay completely cool on the outside and are safe to touch even after hours of use. Infrared heaters do not release any smoke, toxins, or other emissions, and so you can sleep easily even if they run all night. Infrared heaters do not use fans, which makes them great for bedrooms.

If you want to purchase a new infrared space heater, I think the best company going is the aptly named Dr Infrared, which makes heaters that are very high quality, efficient, effective, reliable, and as safe as it gets. I highly recommend the well-designed and hugely popular Dr. Infrared Heater Portable Space Heater, but you can also check out more models at the Dr Infrared Product Page.

Ceramic Heaters

Ceramic heaters are also among the safest of all space heaters. The ceramic elements inside these heaters will never reach extreme temperatures, and the best ceramic heaters will also keep very cool on the outside, so are fine to leave running for hours, as well as being safe around kids and pets. They too are completely emission-free, and while ceramic space heaters do use fans, they tend to whisper quiet, although people sensitive to noise might prefer an infrared type for the bedroom. 

When it comes to ceramic space heaters, I am enormously impressed with Lasko’s products. Their heaters are inexpensive but very well made and well designed, and are among the most recommended of all products here at Know the Flo. I especially like the Lasko Oscillating Tower Ceramic Heater, and their Portable Personal Ceramic Heater is super-affordable and great for smaller spaces.

Oil-Filled Radiators

The way oil-filled radiators retain and radiate heat is ideal for overnight heating, and like the two above types, they will not release any dangerous smoke, fumes, or other emissions. The housing of a radiator heater will get a bit warmer to the touch, but not dangerously so – though for a child’s room, you might be better off with a ceramic or infrared heater. Oil-filled radiators are generally the least dehumidifying of the three types, or of any type of space heater, which is also ideal for extended and overnight use.

If you decide to go with an oil-filled electric radiator, my personal favorites are made by Pelonis. Their 1,500 Watt Electric Radiator is a bit more expensive than others, but is superbly designed and really built to last, and has a premium fit and finish I haven’t seen in any other electric radiators. For a great budget choice, the Costway Oil Filled Radiator is very nice, but keep in mind it has less than half the heating power of the Pelonis, which is thus probably a better value, and more appropriate for larger spaces and colder climates.

What Can You Do to Make Your Space Heater Safer?

The most important thing, and the best way to make sure your electric heater is safe for unattended and overnight use, is to get a new unit with all of the critical safety features and designs we’ve talked about – and the links above will lead you to the best choices for new, safe space heaters of the three best types.

But even if you have the newest, safest, latest, and greatest space heater on the market today, there are still a few things you can do to make it even safer, not just for us all night, or for long, unmonitored periods, but all the time.

  • Never place your space heater, regardless of the type, directly against anything. Even if the heating elements don’t get dangerously hot, and the outer housing stays admirably cool, keeping plenty of room around a space heater will offer that extra level of security and safety, as well as allow it to work more effectively and efficiently.
  • Relatedly, never put anything on top of your space heater, and be absolutely certain it is not near any kind of flammable materials.
  • Never leave your space directly in an unlit walking path. May seem obvious, but make sure you are mindful of the placement of your space heater, to ensure you or any other sleepy person won’t stumble over it heading for your midnight snack.
  • Do not leave your space heater outside overnight, or in any way exposed to water or the elements.
  • Always plug your space heater directly into a wall outlet, rather than using an extension cord. If you must use an extension, make sure it is a heavy-duty variety like the excellent AmazonBasics 15-Foot Extension Cord, and don’t use the extension cord for anything else at the same time.
  • No matter how cool to the touch it is, or how sophisticated and effective the auto-shutdown features are in the cases of overheating or tipping over, you still should never leave a space heater running in the room of a very small child.

Conclusion: Is It Safe to Run an Electric Space Heater Overnight?

To sum up, what we’ve covered in this article, it is not really safe to use an older electric space heater overnight, especially if it does not have the basic safety features I mentioned earlier, like:

  • Overheat Protection
  • Auto Shutdown if Tipped Over
  • Cool Casings
  • Thermostat Control
  • No Emission Designs

If you purchase a brand new space heater, and it has all of these design features, you need not be concerned about leaving the heater running all night.

While this is generally true, it is especially true with three types of space heaters, which you can consider to be the safest to use overnight or for long periods unattended. These three types are:

Even if you have the newest and safest electric space heater, there are several other things you can do to make even more sure that it is safe to use your space heater overnight, as detailed in the section just above.

Hey there! I am Benas, the founder and content editor at Home Caprice. Thanks for reading the article. I hope you were able to find what you were looking for. I and my team are here to simplify heating and cooling for everyone. Please have a look at the About page for more details about our website and feel free to check out our editorial process.