The main purpose of a space heater is to heat a small room. However, it’s easy to think that they could also work outside since they usually do a good job indoors. But can you actually use your space heater outdoors?
Space heaters that use convection heating are not effective outdoors. They need an insulated room to work properly. However, you can use an infrared heater successfully since they’re as effective as patio heaters, though you will need more power to heat large areas.
In this article, I will explain how the different types of portable electric space heaters work in an outdoor environment. Additionally, you will find a comparison of the effectiveness between space heaters and patio heaters. Finally, I will show you how much power you need to heat your outdoor area.
How Do Space Heaters Work?
As I mentioned before, you can use an indoor space heater outdoors. However, its effectiveness will depend on the method they use to produce heat. Not every space heater will be able to successfully heat you up on a cold night outside.
In addition, not every space heater is portable. This is why we will only focus on portable electric heaters.
To understand how well your space heater will do its job outdoors, we first have to look at how they work, their characteristics, and how they compare to outdoor heaters.
There are two main categories for space heaters. Each uses a different method for heating, which will affect its effectiveness outdoors. Let’s dive into these methods and how they work.
Convection is a process of heat transfer through the movement of molecules within gas or liquid. If you add heat to a substance like air, the molecules within will move faster and farther away.
When the air molecules go through this process and get heated, their density decreases, causing the hot air to rise to the top of the room and the cold air stays at the bottom. Through this air circulation, heat is transferred until all of the air inside the room is hot. If you have this type of heating system, you are probably already aware that rooms get heated from top to bottom. That’s the reason why.
In a simplified way, this means that the heat you feel when using this type of space heater comes from heating the molecules in the air. Space heaters commonly do this by heating metal coils, resistance wire, thermal liquids, or ceramic through electricity, which then heat the air around them.
Convection space heaters can also have a fan to help draw cold air and push out the warm air, making the system more convenient.
But how effective are they outdoors?
Since convection heating uses the air to heat a room, it will not be as effective outdoors. Let’s just think about it for a second. In a small insulated room, the heater does a good job keeping it warm because most of the air inside the room will be hot.
However, if you’re outside, there is nothing that contains the air, meaning there will always be more cold air than hot. Additionally, as I mentioned before, the density of the hot air molecules decreases and the air rises. Outside, there is no roof to stop the hot air from going away, making it impossible for a common 1500-watt heater to do its job in an open-air space.
This type of heater will only help you stay warm if you are directly in front of it, so it is not as effective as other options. Moreover, if there is too much wind, all of the hot air will be blown away immediately.
This method consists of using infrared light to make you feel warm. As you might know, light produces heat and we can see it or not depending on its wavelength. Infrared light is just a type of light that is invisible to our eyes. Your temperature increases when you absorb the infrared light emitted by the heaters.
The main difference between convection and radiant heating systems is that the first one heats the air, while the second one heats objects’ surfaces directly.
If you’re wondering how infrared light is capable of producing heat, here’s a basic explanation. Light carries energy and when it hits an object, it makes the particles in the object’s surface move faster. This is what we perceive as heat.
If you’re interested in learning more about infrared light and radiation, check out this quick video:
The reason why infrared light is great for heating is that it carries a lot of energy. But how well does it work outdoors?
Fortunately, infrared space heaters are also great for outdoor use. This is because they’re virtually not affected by the wind or other climate conditions, unlike convection heaters. If you stand inside the range of your infrared space heater and nothing is blocking it, you should be good.
If you think about it, the light from the sun comes from very far away and you can still feel the heat.
However, one disadvantage of common radiant heating systems when used outdoors is that they need to be aiming directly at you. Since the light beams are shot in a single direction, you won’t get heated if you stand outside the heater’s range.
This fact mostly applies to indoor infrared heaters since outdoor heaters are specially designed to heat open areas.
How Do Space Heaters Compare to Patio Heaters?
Patio heaters are designed to be used outdoors. This is why most of them depend on radiant heat to do their job. Now you know why. It’s because convection is not an effective way to heat an outdoor space.
As I previously mentioned, the only way you can use a convection heater outdoors is if you stand right in front of it because it’s impossible for it to successfully warm an outdoor area.
To put this into perspective, a 1500-watt convection heater can heat a well-insulated 45m2 (150ft2) room with an 8 ft high ceiling. Considering there is no insulation outside, convection heating won’t be effective.
On the other hand, infrared heaters work the same way as patio heaters. The most important difference between these types of heaters, aside from the design, is their power.
The amount of power you will need depends on the area you are trying to heat. A common infrared space heater uses up to 1500 watts. This is enough power for a small to medium area. In contrast, patio heaters can go up to 6000 watts.
Here is a table showing you how much power you’ll need to heat your desired outdoor area.
Watts M2 Ft2
750 5 16
1500 10 32
2250 15 49
3000 20 65
3750 25 82
4500 30 98
5250 35 114
6000 40 131
This data was calculated based on achieving a temperature of 18ºC to 24ºC (64ºF to 75ºF).
Convection space heaters are ineffective at heating outdoor areas. The only way you can use one outdoors is by being right in front of it where you can feel the hot air. Although, if there is too much wind, there is a possibility it won’t be useful at all.
On the other hand, infrared heaters work just as well as patio heaters outdoors. However, you’ll need more power to heat large areas.
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.