The heat range of a patio heater
To determine the heat range, a patio heater is tested in an enclosed space of 18°C where the wind has no influence. During this kind of test, sensors in the floor measure at which maximum distance the heat can still be felt. For example, you have a heater with a range of 15m². This doesn't mean the heater feels just as warm at a distance of 10m² as it does at 15m². You can still feel the heat, but not as much. That is why you shouldn't take the heating range too literally. In the image, you can clearly see that the heat intensity of the light decreases a little bit at a time.
Heaters are tested in an ideal situation of 18°C where the wind has no influence. In reality, this isn't a very common situation. Perhaps your heater is mounted in a windy, open space where the outdoor temperature is 14°C. In that case, a heating range of 15m² as measured in the test situation is unrealistic. In the image, you can see that even in the first arc, there is already less thermal radiation than in the ideal situation due to wind and a lower temperature.
The images above show the heat radiation of a round heater. But there are also other models, of course. Think of a hanging, rectangular heater whereby the heat isn't spread around the heater. The image on the side shows what the thermal radiation looks like in this case.
Type of heating element
The temperature and wind sensitivity of your space aren't the only factors that have an impact on the heat range. There is also the type of heating element. Various heating elements are possible including golden tube, halogen, carbon, and quartz. Each type of heat lamp has different features. For example, a golden tube is the least sensitive to wind and quartz the most. Want a heater with a 20m² heating range? There is a big difference between a golden tube or quartz heater with a range of 20m². Wind has little influence on a golden tube heater, but it does affect the thermal radiation of a quartz heater. A quartz lamp is of lesser quality.
We give an indication of the heating range with each heater. Don't take this too literally. Various factors like wind and temperature can cause the thermal radiation to decrease. In addition, the heat at a distance of 10 meters is not the same as at a distance of 15 meters. You'll still feel the heat, but the intensity decreases. Keep this in mind when you purchase a heater for a room that is subject to weather conditions.