8 facts about far infrared heaters

Surely, heaters are the most important part of every far infrared sauna. They produce heat, that’s why this wooden box is known as sauna. Majority of heat they provide comes in a form of infrared (or thermal) radiation, that’s why this type of heaters is called infrared (far infrared) or radiant heaters. Promotional efforts of majority of brands are centered on heaters used in a sauna, trying to make buyer believe that they have the best heater. Arguments used are wavelengths, heaters temperature, heaters surface area, heaters material, heaters positions, heaters form and heaters working cycle. Promises of best «vital» wavelength and best distribution of heat (both in time and space) are heard from everywhere. In addition to that, companies don’t hesitate to critic heaters from their competitors.

This high level of noise leads to the situation that it is very hard for customer to make decision about what heater he wants in his sauna. The fact that heaters looks like most sophisticated part of the sauna (in contrary to wooden enclosure, lighting, ventilation and other things) adds more confusion. And things look more complicated, because far infrared sauna companies often use words like «patented» and «research» as well as scientific terms in description of their heaters.

In reality, understanding how heater works is nothing complicated. Big part of the noise around far infrared heaters is overemphasized. This is my opinion and I’m going to make two claims about infrared heaters and support them with facts.

Claim 1. The difference between infrared rays generated by different heater types in not so important; in fact, it is less important than other aspects of heaters.

Fact 1. Range of wavelengths emitted from a heater depends only on it’s temperature (see thermal radiation). Radiant heaters don’t contain any other technology other than heating heater material with metal coil embedded into it. Current passes through metal coil, heats it (similar to common light bulb), and then heat is transferred from the coil to the heater body.

Fact 2. Temperature of heaters used in a far infrared sauna range from approx. 60 C (140 F) (some carbon heaters, but even these heaters usually operate at higher temperature) to 760 C (1400 F) (incoloy or aluminium heaters).

Fact 3. Peak wavelength of a heater with 60 C (140 F) is 8,7 micron (Wien’s Law), and peak wavelength of a heater with 760 C (1400 F) is 2,8 micron. Both lie in middle-far infrared part of the spectrum. And for every heater wavelengths emitted are quite evenly distributed around it’s peak wavelength (see Planck’s law of radiation illustrated on this picture).

Fact 4. Infrared just heat our bodies. It transfers energy from heaters to the surface of a human body. That’s all. All effects that infrared sauna has follows from this fact. I’ve seen no reference to researches or other sources for claims that certain infrared wavelengths are more beneficial to human than others.

Fact 5. Walls at room temperature 20 C (68 F) emit far infrared with peak at 9,8 micron. Human, standing in a room, receives about 400 watts of infrared heat from walls, ceiling and floor. So the key property of a far infrared sauna is heat, not far infrared.

Claim 2. Most important thing in a far infrared sauna is how even heat is distributed over the human body, and how this heat changes throughout the sauna session. Any heaters will do if they provide good heat distribution in time and space.

Fact 6. Situation when one part of the body is heated less than other (for example legs and torso) is unpleasant and thus unacceptable. It can even be dangerous, since thermoregulation systems of our body can become confused and to not react adequately to overheating.

Fact 7. To maintain sauna temperature at constant level, sauna companies use different solutions: to switch heaters on and off throughout sauna session, to reduce power of the heater as temperature rises, or to keep heater power constant but to increase ventilation. Different methods lead to different sensations and different body reaction while taking a sauna.

Fact 8. Heat distribution and change of heat intensity with time lies much in a field of personal preferences. One person can dislike his head heated, others don’t. Some people can like gradually rising and falling heat level, others can like constant heat plus ventilation. There is no perfect solution for all.

From these two claims I want to draw a following conclusion:
Generally, you don’t need to bother with heaters type, as long as sauna satisfies you in terms of heat distribution and heaters mode of operations. To know, which far infrared sauna is best for you, it is better to try several different brands and to play with different temperatures and ventilation options.

Tags: , , , , ,

One Response to “8 facts about far infrared heaters”

  1. derrick Says:

    all this info is helpful, but i live in the northeast where there are very few sauna dealers where i can actually try saunas out. it’s hot tub country here. do you have a favorite few saunas(mfg., models. etc.) that you like? does it matter if it is china built? does the weight of the sauna have any relationship with the quality?