Introduction to Underfloor Heating

All underfloor heating systems, whether “wet” or “dry”, essentially work in the same way. Heat, either from warm water flowing through pipes, from electrical heating cables, or from heat mats, radiates upwards from beneath the floor into the room above.

This emits a more natural temperature gradient than traditional radiator systems, which tend to heat the space immediately below the ceiling first and, because the entire surface area of the floor is used for heating, less energy per unit area is required.

This effectively means that not only can comfortable conditions be achieved at lower air temperatures – typically 2°C lower – than with traditional radiators, but also that underfloor heating systems can be more energy efficient, and economical.


Types of Underfloor Heating


So called “wet” underfloor heating systems circulate warm, rather than hot, water – typically at a temperature of around 50°C and therefore much cooler than a traditional radiator, which may have an operating temperature of 80°C or 90°C – around a series of continuous pipe loops beneath the floor.

A wet underfloor heating system could be up to 30% more efficient than a traditional radiator system and therefore economical as the main form of heating in your home, plus, it also frees wall and floor space otherwise occupied by radiators, so that you can design your interior to greater effect.

Gas, oil and solid fuel boilers can all be used as a source of heat for a wet underfloor heating system – although condensing boilers are usually the most efficient in this context – and integrating a system with your existing plumbing, including radiators if you do not wish to have underfloor heating throughout your home, is a definite possibility. Be aware that like any form of heating system, wet underfloor heating will only work efficiently if your home, including the sub-floor, is properly insulated against heat loss.


So-called “dry”, or electric underfloor heating systems are available in the form of basic heating cables, sometimes loosely woven into mesh mats, flat or ribbon cables, or heating films.

Electric underfloor heating systems, on the whole, allow a room to reach the required temperature faster than wet systems, because they are a direct heat sources, however, they may also be anything up to 40% more expensive to run than wet systems.

Some less expensive electric systems may be unsuitable for installation beneath engineered or laminated wood flooring, but ribbon cables which operate at a temperature as low as 30°C, are available and these can be installed without danger to the colour, texture, etc. of these and other sensitive floor coverings, such as carpet or linoleum.

Underfloor Heating Installation

Nowadays the pipework installed as part of “wet” underfloor heating systems, is typically high quality – PEX (the generic name for polybutylene, or polyethylene) and Alupex™ (a five-layer composite of PEX and aluminium) are popular materials and are continuous, so there is no danger of leaking from joints.

“Wet” underfloor heating systems are, however, best suited for inclusion in newly built homes because of the disruption and expense involved in taking up the floor(s) of an existing property. Repair, or maintenance, of “wet” underfloor heating systems, if it is required, may prove troublesome and costly, so reliable materials are a necessity. A “wet” system also requires space for timer controls, individual valves for each room, etc., preferably positioned together in a single location, such as a cupboard.

Electrical underfloor heating is more appropriate for renovation projects in existing properties, as heating cables, or mats, are laid on top of the existing sub-floor, or insulation board, so that the height of the floor need only be raised by a few millimetres, at most.

Electric underfloor heating is easy to install and inexpensive, especially if you wish to heat a single room, such as bathroom, for short periods.