Basics Concepts of Radiant Heating



What is Radiant Heating

Radiant Heating is a process where the energy in a form of heat is transferred from an object with higher surface temperature (such as a heating cable) to the object with lower surface temperature (such as floor). Radiant energy is also called thermal energy and is essentially infrared electromagnetic radiation which is unseen by a human eye and can only made visible with the help of an infrared camera.
 

How It Works

Radiant heat is emitted equally in all direction and travels through space at a speed of light. The basic concept of heat is that it is always emitted by hotter and absorbed by cooler objects, which makes the process of radiant heating and consequentially, radiant floor heating possible.

The rate at which the heat is transferred is governed by several variables such as the distance between the objects, the ∆T (delta T) or difference between surface temperatures and the absorption and emission properties of both objects.
For example, a person sitting 4 feet in front of the fireplace will feel much warmer then the person sitting 12 feet away from it. Similarly, heating a cooking pot filled with 120˚F water will take less time to boil then the one filled with 55˚F water. Objects with reflective metallic surface such as aluminum foil reflect a lot of thermal energy and therefore are commonly used in building insulation, whereas dark colors accommodate heat absorption and are therefore common for solar collectors.
 

Interesting Facts

One of the most interesting and in our case, very useful properties of radiant heat is that the air absorbs very little of it. When a person walks into a room with radiant heated floor, it is not the air which makes him/her feel warm, but rather the heat emitted by the radiant floor and absorbed by that person. This explains why forced air heating systems are so inefficient and inferior to radiant floor heat systems.

As mentioned above, infrared radiation is not seen to the human eye, that is, unless the object becomes really hot. When a chunk of metal such as iron is heated to about 1000˚F, it starts to glow, giving a good visual example or infrared energy at work. Radiant heated floors, of course, do not get heated to such temperatures and we can only feel the infrared energy but not see it.
 

Misconceptions

Some may mistake infrared radiation for nuclear radiation. These are two completely different types of energy and infrared radiation does not emit subatomic particles which pose hazards to human health.
Such misconception would be similar to comparing the visible daylight (which is radiation with wavelength of 400-700nm) with X-ray radiation (wavelength of <10nm). One is the source of life, the other is the end of it.
Making this distinction is very important to eliminate the confusion and sometimes discomfort associated with the word “radiation”.
 

Applications

Radiant heat is present everywhere in nature – Sun heating the surface of the Earth, volcanoes, geysers and so on. Humans have used thermal energy since ancient times, with early radiant heated floors dating back to Roman Empire. Today, products such as electric heating cable and mats from HeatTech help to create warm floors which offer the highest level of comfort, energy efficiency and a peace of mind.