What Is radiant heat?

When your heating systems installation professional talks about radiant heat, he or she is referring to a method of climate control wherein a room is heated via surfaces in the room. In the past, this meant metal radiators in the corners of rooms, which were heated by boiling water. But these often burned anyone unfortunate enough to touch them, and anyone who's ever lived in an old home knows about the annoying knocks that came from the pipes. Modern radiant heat systems radiate heat from the walls or (more often) the floor, which have more surface area and therefore don't need to heat up as much. That way, nobody gets burned.

How is it different from forced-air heating systems?

For one thing, radiant heat is more efficient. Because forced-air heating involves a lot of hot air flowing through ductwork, it loses energy. And forced-air heating is harder on those of us with bad allergies, since it stirs up dust and other allergens. What's more, radiant heat distributes heat throughout the room in a calmer and more equitable manner; whereas forced-air heat tends to create erratic air currents which in turn create hot spots and cold spots around the room, radiant floor heating allows heated air to rise slowly from the floor to the ceiling. As a result, energy is not lost until the air reaches the highest point in the room. So unless you're sleeping on the ceiling, radiant heat is likely the better choice for your home.

What's the science behind radiant heat?

Radiant heat, in scientific terms, is known as thermal radiation -- a form of electromagnetic radiation that emanates from the surface of an object as a result of its temperature. In short, every object radiates energy because of its temperature, and every object absorbs radiant energy from its surroundings. Thus, a cooler object (like you) will absorb heat from a warmer object (like a floor warmed by a radiant heat system). In the case of radiant floor heating, the floor is substantially warmer than the temperature of either you or the air, so it keeps both your feet and the room nice and toasty.

What methods of radiant heating are out there?

Most radiant heating systems emit heat from the floor, since that's the most efficient way to heat a room using radiant heat. Electric radiant floor heating utilizes electric coils or mats of conductive plastic built into the floor. Air-heated radiant floors use a furnace to pump heated air through the floors. And hydronic radiant floor heaters use heated liquid to warm the floors, which then radiates heat through the room.

How efficient is radiant heat?