"What is INFRARED:
What's special about infrared radiation is that it heats the objects and people in its path, rather than just heating the air. This makes infrared heating much more efficient than convection heating, which is the form of heating used by conventional radiators and oil or gas central heating systems. Convected heat warms the air only, which circulates uncontrollably and leaves the surrounding fabric of the room cool. Direct radiated heat warms everything it touches, bringing a lasting, comfortable heat to your home whilst consuming less energy.
 "Heater Output:​​"
The heater output is detailed under each respective model, primarily this is the maximum output that can be gained via a standard 10 amp plug connection.

It is importnat to note that the "heat" felt from an Infrared heater is significanly affected by the surrounding air temperature.  As an example a cold winter night of say 10 deg will give half the heat effect , versus a mid summer night of 20 deg .  
Hence if you are planning to use heaters in winter or in colder climates you will require more units.
"Where Can You Use Infrared"
Indoors and outdoors, domestic and commercial – infrared heaters can be used everywhere! Efficient, eco-friendly and more comfortable than conventional central heating systems, infrared heaters are ideal heating solutions for all domestic and commercial spaces. They're especially useful in warehouses and outdoor locations because they overcome the problems of convection heaters that have made these spaces almost impossible to heat in the past. Convection heaters only work when they can heat an entire space – that's a very large space inside a warehouse, or an infinite space in outdoor locations! Infrared heaters, however, can provide directed heat wherever it's needed. This means you don't waste power needlessly heating an entire warehouse and heat isn't lost through the circulation of air. Infrared provides superior energy-efficiency and effective, far-reaching warmth – it's a heating revolution for all large and open plan spaces
"Is Infrared Safe""
“Infrared radiation” sounds a little scary, so perhaps it’s unsurprising that some people worry that infrared heating might carry health risks. Don’t be put off by the technical jargon – infrared radiation is a natural form of heat which you experience on a daily basis, from the warmth of the sun to the heat given off by your own body. All radiated heat travels in infrared waves, so if you’re currently using radiators, you’ve already heated your home with infrared radiation to a degree. Far infrared radiation – the gentlest form of infrared in the spectrum – is so safe it is commonly used in incubators for babies. Infrared heaters offer a very safe and practical heating solution, with many benefits over more traditional forms of heating. They do not produce carbon monoxide, so they don’t need to be serviced; they heat purely by radiation, so they do not generate convection currents or agitate allergies; they operate entirely silently; they are all fitted with a thermal cut out to prevent overheating; and the radiated heat feels especially comfortable, like the heat from the sun.​