Space heaters are a simple (and affordable way) to keep your home warm during the chilly winter months. Offered in a variety of sizes, you’ll find models designed for small offices, sprawling living rooms, and everything in between. However, space heaters are also responsible for house fires and other accidents — meaning you have to be careful with how you use them.

Before rushing out and adding a space heater to your home, here are a few things to consider. From checking available safety features and finding the right size to placing it in your home and avoiding smart plugs, here’s everything you need to know about these useful gadgets.

The most important feature to look for in a space heater is the tip-over switch. Products with a tip-over switch will automatically turn off when they’re knocked over, making it an indispensable safety feature. It’s rare to find products without a tip-over switch nowadays, as all the best space heaters use them.  But if you’re shopping for older devices, be sure it has one of these. If it doesn’t, the heater will pose a serious fire hazard if it gets knocked over.

Additionally, check for third-party safety certifications. These typically come from the Underwriters Laboratory or Intertek Group. If they’ve been certified, they’ll have a “UL” or “ETL” logo on their packaging. Certified products have been tested to high safety standards, and you can use them confidently in your home.

Whether you need to fill a massive studio or a cramped cubicle, there’s a space heater sized for your space. Most products will tell you the size of room they’re designed for — make sure you look at this information and find the best one for your needs. That means you won’t want to just rush out and buy whichever one has earned the best reviews online, as it might not be designed to handle the type of space where you plan to use it.

The same goes for the type of space heater. Some space heaters create direction heat, meaning they’ll push out hot air like a fan. Others are radiant and slowly warm up the entire room. Radiator-type space heaters tend to be popular choices for large spaces and all-day warmth, while directional heaters typically heat up faster.

Space heaters require a lot of energy, and that means they pull a lot of electricity. Because of this, most are not rated to work with extension cords and must be plugged directly into your wall outlet. Using a space heater with an extension cord could lead to electrical issues and damage to your devices.

The instruction manual should point this out to you, but it’s something to keep in mind before making a purchase. If you need to place a space heater somewhere far away from an outlet, consider shopping for models with a lengthy cable.

While some space heaters might be compatible with smart plugs, combining the two isn’t the best idea. The risk of accidentally toggling on a space heater while away from home is a serious fire hazard, and it’s not a risk most users will want to deal with. If you do decide to use a smart plug with a compatible space heater, you’ll need to be remarkably careful and keep a close eye on both your space heater and your mobile companion app.

If you have pets or small children in the home, unplugging your space heater when it’s not in use is incredibly important. The last thing you need is for someone to accidentally turn on the heater or trip over its cable. Leaving a space heater plugged means you’re opening yourself up to a variety of unsupervised accidents, so it’s best to just unplug it after each use. Once the heater is unplugged, it’s virtually impossible for an accident to occur.

It should go without saying, but space heaters shouldn’t be placed close to flammable objects or furniture. Even if something isn’t flammable, space heaters can cause objects to melt or warp. They churn out serious heat — and it’s not uncommon for temperatures to reach well over 100 degrees Fahrenheit right next to their fans. If you have children or pets, make sure the space heater is in a place they can’t reach. In addition, it’s a good idea to periodically check the space heater to see if anyone has accidentally placed objects too close to its powerful heat waves.