The temperature output by a heater is dictated by the peak wavelength of thermal energy the emitter is designed to produce.   All materials absorb heat differently according to the composition of the material itself plus its thickness. So the intended use of an emitter is a function of that peak wavelength plus the overall power being supplied to the emitter.

The three types of Infrared heater

There are 3 types of Infrared Heaters:

High Intensity Near Infrared Heater

“Near Infrared”, “IRA”, “Short wave” or “Bright” Infrared heaters and “Heat Lamps” operate between 0.75 to 1.4 microns and emit temperatures of 1300°C and more plus a bright red visible light. Emitters are typically Quartz-Tungsten with a reflector to concentrate the heat in a particular direction. There are also gas-fired Near Infrared heaters which burn propane or natural gas through a venturi to heat a steel tube, which glows sufficiently hot to produce the near infrared.

The “hotter” the IR lamp, the more transmissive it is, meaning it can travel greater distances in narrower “beams” and be useful for immediate warm-up or instantaneous “boost” functions or for overcoming long distances, higher airflow, or colder temperatures. Therefore Near Infrared’s application in comfort heating is appropriate where installation heights, airflow levels or low background temperatures prevent the use of gentler heaters lower down, which makes it suitable for harsher / more difficult to heat situations. The Herschel MIAMI is an example of an effective Near Infrared Comfort heater for public use and the Herschel Vulcan is an example of a Near Infrared heater for Industrial use.

 

Medium-wave Infrared emitters

“Medium Infrared”, “IRB” or “Medium Wave “ infrared heaters  operate between 1.4 to 3 microns and emit temperatures  of 500 – 800°C and produce a deep red light (like bar fires).

This type of infrared is the classic “glowing embers” of a bonfire or coal barbecue. This is the waveband with the best mixture of transmissiveness (to cover the distance) and absorbency (to warm us up) and is really the “sweet spot” – the most effective region – for Space Heating large areas. Think about sitting around a camp fire – which is emitting at exactly these wavelengths. Go a bit hotter (towards Near IR) and you can get more projection out of the heater, or overcome a bit more airflow but the heat itself is not so comfortable. Go a bit cooler (towards Far IR), you can get closer, feel more generally and thoroughly warmed. Think in these terms for space heating too. The Herschel Colorado and California are great examples of effective Medium Infrared heaters.

 

Long/Medium-wave infrared emitter

Ceramic Emitters peak in the Far infrared wavelength (at 3 microns). This makes these sorts of emitter ideal for public and commercial “Space” heating applications where mounting heights can be lower, where there is little airflow or background temperatures are higher. The advantage with these types of space heater over “hotter” (i.e. glowing) lamp heaters is that they do not emit any light, only heat, which confers considerable advantages in certain applications.

Herschel uses this type of emitter in its Advantage – Indoor Commercial and Aspect – Outdoor patio and terrace space heating ranges.

 

 

 

Far infrared heater

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 100°C mark and no visible light.  Human and animal skin absorbs Far infrared specifically well, because of its 80% water composition, making Far Infrared a biologically significant heating wavelength for humans and animals.

Far Infrared heaters use a number of different elements, with popular ones being nickel or fecralloy wiring or more recently carbon fibre.

Because of their lower temperatures, applications of “Far Infrared” heating include Domestic, Commercial and Public “comfort” heating applications.  It is also also used extensively in modern saunas.

Herschel uses this type of emitter in its Inspire, Select XL and Select panel ranges.

 

General functional requirements to Infrared Type matrix

On the basis of the preceding, the following table shows approximately the considerations for matching the right type of infrared to the right requirement (for heating people).

Difficult-to-heat spaces

Large open space to heat;

Higher installation heights;

Higher airflow possible;

Colder Temperatures.

Use Near or Near-Medium Infrared

Space heating (colder, windier)

Large open space to heat;

Lower Installations heights;

Moderate Airflow;

Moderately cold temperatures.

Medium or Ceramic Far Infrared

Comfort Heating

Smaller spaces to heat;”Comfort” temperatures required;Within “touch” of people.

Far Infrared panel heaters

 

Publisher: Herschel Far Infrared