Radiant under floor heating may sound like a modern invention but, it's not.

Today, radiant under floor heating is available inexpensively, provides you with options as to what system you prefer to use and it is easy and inexpensive to install.

In Korea the equivalent of radiant underfloor heating has been around since the era of the Three Kingdoms (37 BC - 668 AD).

Referred to as "ondol", in Korea, radiant under floor heating "comprised three main components: a fireplace or stove, which is also used for cooking and located below floor level; a heated floor underlaid by horizontal smoke passages; and a vertical chimney, located lower than the roofline, to provide a draft. The heated floor comprised a network of underground flues that transported heat from the kitchen to each room. These flues were covered by thin, flat, wide stones two or three inches thick called kudul that lay underneath the floor. Kudul, literally meaning "fired stone", was covered with yellow earth, and the floor was leveled. To top it off, several layers of yellow paper sheets were pasted on the floor. This process was efficient since the heat and smoke generated during cooking would be transported automatically to each room in the house. Usually the kitchen would be built at a lower level (about one m), and the heated rooms would be in an elevated position to allow the flues to run underneath. Notably, with just one heating the floors would retain their warmth for extended periods, ranging from more than 30 days to three months depending on the design of the flue structure." (www.wikipedia.org)

Other civilizations such as the Romans as well as Muslim engineers were using this system prior to the 12th Century. Since the Middle Ages till recent times a system called "Gloria", based on the Korean ondol system, has been in use in Castille.

In the 1900's Frank Lloyd Wright, the famous American architect, through his invention was the first to introduce radiant floor heating in the US. Instead of using hot air, Wright introduced the system using hot water. Today, there are two ways in which to heat your floors. One is with hot water and the other electricity.

(Photo courtesy of crouchingbadger, Flickr.)

Radiant under floor heating provided by hot water is rather simple to install. It is composed of pipes or tubes, which are laid down on the floor and circulate back and forth the entire surface to be warmed. It is through these pipes that the hot water circulates. "In a hot-water system, warm water is circulated through pipes or tubes that are laid into the floor (usually a solid-screened floor, although joist-based systems also work well). Various types of pipe are used including PEX, multi-layer (a composite of PEX, aluminium and PEX) which is also known as Alupex (there is also a version using PERT instead of the PEX) and polybutylene (PB): copper pipes are not normally used" (www.wikipedia.org)

"The tubing is usually encased in a slab of concrete or lighter-weight gypsum cement. In some cases, the tubing can be fastened to the underside of subflooring instead." (www.hometips.com)

(Photo courtesy of crouchingbadger, Flickr.)

The electric radiant heat system is electricity operated and includes "carpet heaters, portable under area rug heaters, under laminate floor heaters, under tile heating and floor warming systems, under shower floor and seat heating, under vinyl and linoleum heating, and under hardwood floor heating systems for wood floors. Some systems are required to be placed in a mud bed for UL certification for under wood, laminate, and carpet. Other systems, known as dry install systems, are installed directly on the sub floor or on top of the carpet padding - directly in touch with the floor covering." (www.wikipedia.org)

There are several different installation forms which include "one long, continuous length of cable with the consumer having to weave the cable up and down the floor at a pre-determined spacing and making a return loop to complete the circuit, or they can be provided in mat form, where the heating element is pre-formed in a mat that rolls out onto the floor. Most high voltage cables have a built in return, meaning that you have one end to connect. Most technologies consist of a loop with a start and end. With the introduction of the built in return came the "cable mat". Cable mats have added to the ease of installing a floor heating system by having the heating cable already pre-spaced on to a nylon mesh. Cable mats however can cause issues for odd shaped spaces where a free rolled cable may be able to cover in a more custom pattern.

One technique is to lay the heating cable directly onto an insulated concrete floor and then apply tile on top of it. Where time-of-use electricity metering is available, this type of system can be turned on at night when electricity rates are low, and then allowed to warm the house during the day by relying on the heat energy held within the thermal mass of the concrete.

(Photo and text courtesy of ianhaycox, Flickr.)

Sometimes, in order to minimize floor buildup, a bronze screen or a carbon film heating element is used. Carbon film systems are normally installed onto a thin insulation underlay (approx 6mm) to reduce thermal loss to the sub-floor. Carbon film is used under various floor finishes, traditionally laminates flooring or engineered wood. Vinyl, carpet and other "soft" floor finishes can be heated using carbon film elements or bronze screen elements, provided a suitable over-boarding system is used." (www.wikipedia.org)

The advantages of opting for a radiant under floor heating system are multiple. These include thermal and dust control, it's easier on the eye since it is "invisible", there is a reduction of heat loss and the system is more energy efficient in comparison to a forced air system.