Outdoor Infrared Heaters
“Outdoor infrared heaters” is an umbrella term commonly used to refer to a wide range of heaters. Some glow, some don’t; some produce a high level of heat, some are very gentle; some can withstand torrential rain and gale-force winds, while others should only be used in covered locations.
There are only two things these heaters all have in common. Firstly, they share the same basic design, with a bar-shaped heating element protected by a metal grill. Secondly, and more fundamentally, they all heat using infrared radiation.
What is heat radiation?
Heat radiation is a bit of a scary-sounding concept – but in fact nothing could be more ordinary. All warm objects radiate heat when their surroundings are cooler and absorb radiated heat from warmer objects. Take a look around you. Pretty much everything you see will be radiating or absorbing heat – most things will be doing both! When you take a walk on a sunny winter’s day, you’ll be both absorbing radiated heat from the sun and radiating heat out into the chilly air.
What is infrared radiation?
So, radiated heat heats objects directly without heating the air – which is what makes infrared such an effective outdoor heating solution. But what exactly is infrared? How does it work?
Infrared is a form of electromagnetic radiation. Electromagnetic radiation covers a huge spectrum of phenomena which includes everything from gamma rays, at one end of the spectrum, to radio waves, at the other. Electromagnetic radiation interacts with matter in very different ways across the spectrum: radio waves, microwaves, infrared, visible light, ultra-violet light, x-rays and gamma rays are all forms of electromagnetic radiation. However, the infrared section of the electromagnetic spectrum encompasses only those electromagnetic waves with frequencies between 430 THz and 300GHz.
It’s a common misconception that only infrared waves transmit heat; in fact, many forms of electromagnetic radiation can radiate heat. The temperature of an object determines the wavelength of the heat radiation it will give off – at very high temperatures, the radiation given off extends into the region of visible light and beyond. Think about the glowing tip of a blacksmith’s poker – that’s an example of an object giving off heat in the visible light section of the electromagnetic spectrum. However, most of the temperatures we come across on a daily basis radiate heat at wavelengths which fall into the infrared portion of the spectrum – from the temperatures we heat our homes to the heat given off by our own bodies – so, as far as heating is concerned, infrared and heat radiation are pretty much the same thing.
All the radiated heat given off by central heating radiators, electric radiators, towel rails, wood-burning stoves and underfloor heating systems, is given off as infrared heat. This is true of all home heating solutions that give off any of their heat through radiation. What makes infrared heaters special is that they only give off infrared heat.
Heaters vs Panels
But today, numerous manufacturers have found a way around this problem, either by using a very hot element which is protected within the metal casing, or by distributing the heating elements over a large surface area so they do not need to get so hot. These two different approaches give us two main types of infrared heater: indoor panel heaters, and outdoor infrared heaters.
Infrared panels make radiant heating possible using the larger surface area principle. These ultra-slim aluminium panels have a long reel of heating wire fitted inside them that spreads heat over the entire panel. Because the panels have a large surface area, they need get no hotter than 90 °C, which is equivalent to the surface temperatures reached by radiators – so you won’t burn by brushing against the panels. This is the same principle used by underfloor heating, which heats entirely through radiation using a very large surface area – your floor! Infrared panels are an increasingly popular home heating solution – go to the Infrared Panels Buying Guide to find out more.
Outdoor infrared heaters differentiate themselves from panels by using very hot heating elements to generate radiated heat. Depending on the technology used, the heating element will reach temperatures of between 300 and 2600 °C – obviously far too hot to touch, so the elements are encased within the housing and protected by a metal grill at the mouth of the heater. They are usually wall or ceiling mounted to keep them away from children.
The type of element used and the level of heat given off varies from heater to heater, with a wide range of models available with something to suit all kinds of outdoor spaces – and some indoor.
Radiated heat is a particular boon in outdoor spaces, where convection heat is useless because it diffuses away to colder spaces. However, it also has many benefits for indoor spaces, especially in draughty, high-ceilinged rooms which are inefficient to heat by convection because of the large volume of air that would need heating. Warehouses, factories and churches are just some of the indoor locations that can benefit from outdoor infrared technology. Heaters within the outdoor heater family have also proved popular in bathrooms, workshops and conservatories, where the fast heat-up times make them ideal for on-demand heating.