Herschel Far Infrared emits the biologically most significant Comfort Heating wavelengths because skin content is 80% water which absorbs heat most efficiently from wavelengths of 3 microns and lower (Far Infrared). Far Infrared is better absorbed by the skin, is less transmissive (passes through) and is less reflected.
Infrared wavelengths themselves are divided into 3 distinct categories, due to the different physical characteristics of each wavelength.
“Near Infrared”, “IRA”, “Short wave” or “Bright” Infrared heaters and “Heat Lamps” operate between 0.78 microns to 1.4 microns and emit temperatures of 1300°C and more plus a certain amount of “deep red” visible light. Applications of this technology include heat lamps for food preparation; large volume “Space” heating requirements and certain carefully controlled medical applications.
“Medium Infrared”, “IRB” or “Medium Wave “ infrared heaters operate between 1.4 microns and 3.0 microns and emit temperatures in the high hundreds of °C. Middlewave is valuable for Space heating in cold locations or where there is a lot of airflow due to its more transmissive properties over Far Infrared. Industrial applications of this technology include autoclaves and plastic welding.
“Far infrared”, “IRC”, “Long wave” or “Dark Radiators” operate in the wavelengths above 3 microns. Far Infrared elements emit much lower temperatures, typically around the 85-95°C mark and no visible light. This is the wavelength used in domestic “comfort” heating and Infrared Sauna applications.
“Far Infrared” is consequently the only applicable technology for a “comfort” heating application.