Radiant Heat Information
What is Radiant Heating?
 Before discussing the
installation details of radiant floor heating, it’s important to have a
clear understanding of how radiant heating works as well as how it
differs from other forms of heating.
Conduction
is how heat moves through solid materials, or from one solid material to
another when the two are in contact. If you stand barefooted on a cool
basement floor slab, heat transfers from your feet to the floor by
conduction.
Convection
is how heat moves between a solid surface and a fluid. The fluid may be
either a liquid or a gas. Hot water flowing through a pipe transfers
heat to the inside wall of the pipe by convection. Likewise, air flowing
across the heat exchanger inside a furnace absorbs heat from the hot
metal surfaces.
Radiant heat
transfer occurs when infrared light leaves the surface of an
object and travels to the surface(s) of other cooler objects. Unlike
conduction and convection, radiant heat transfer does not require a
fluid or solid material between the two objects transferring heating. It
only requires a space between the two objects. The radiant energy only
becomes sensible heat when absorbed by a surface.
The radiant heat emitted by the relatively low
temperature heat emitters used in hydronic heating is technically
described as infrared electromagnetic radiation. It’s simply light that
the human eye can’t see. However, other than the fact that it’s
invisible, infrared light behaves just like visible light. It travels in
straight lines at the speed of light (186,000 miles per second), and can
be partially reflected by polished metallic surfaces. Unlike warm air,
radiant energy travels equally well in any direction. Up, down or
sideways, direction simply doesn’t matter. This characteristic allows a
heated ceiling to deliver radiant heat to the room below. The
radiant heat emitted by a warm floor, wall or ceiling is a completely
natural phenomenon that’s literally as old as the universe itself. A
surface warmed by sunlight gives off infrared radiation just like one
warmed by embedded
tubing.
The latter simply uses a different heat source and transport system to
deliver heat to the surface. Most low temperature radiant heat panels
emit less than 1/10 the radiant flux of bright sunlight, and all of it
is infrared as opposed to ultraviolet light. Even the human body gives
off infrared radiation to cooler surrounding surfaces.
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