New opportunities for electric underfloor heating

Electric underfloor heating requires little depth and can be used with a wide range of floor finishes — including wood, tile, laminate and heat-resistant carpet.
Technological advances in recent years enable electric underfloor heating systems to provide optimum comfort and be economically viable, says SIMON BRODERICK.Electric underfloor heating is fast becoming recognised as a reliable and economic way of heating spaces in offices and homes. This is partly due to TV programmes on home improvements. More significantly, electric underfloor heating has shed the somewhat negative reputation it gained during the 1970s as a result of poor insulation and poor power regulation. It now not only provides optimum comfort conditions, but also is extremely economic. In fact, electric systems can help meet the energy saving requirements of Part L of the Building Regulations. In addition, unique ‘intelligent’ self-regulating systems and accessories are available that can boost the possible energy savings by an extra 20% or more. Attractions A major attraction of electric underfloor heating is that it is easy to install — not only in new builds but also in refurbishments and renovations. Further, it can be laid under most floor types — wood, tile, laminate and heat-resistant carpet. Another advantage is that it can be installed on any kind of sub floor — wood, plaster or concrete. In other words, it can be installed in spaces where it might be difficult or even impossible to fit other forms of underfloor heating. There is no need, for instance, to install raised floors to accommodate heating cables or mats. With the use of sophisticated thermostats, ambient and floor temperatures are automatically controlled to ensure optimum comfort conditions and the efficient use of energy. The great advantage of electric underfloor heating is that it distributes heat evenly. In a room with conventional radiators with a surface temperature of 65°C, the temperature variations in areas of the room away from the radiators will range from 18°C at floor level through 23°C and 25°C at different heights to 26°C below the ceiling — depending, of course, on the distance from the radiator. With an underfloor system achieving a temperature at floor level of 25°C, the average temperature at different levels throughout the room will be lower, but occupants will feel more comfortable. This reduction in temperature variation can significantly affect on overall heating costs. Air movement There is less air movement with underfloor heating, which means less dust movement, making it more hygienic. Research in 21 households in mainland Europe showed a 50 to 80% reduction in domestic mite populations in households with floor heating, improving the quality of life, especially for allergy sufferers. As floors dry faster in wet areas such as in bathrooms, a build up of fungi and mould is also avoided, adding to its hygiene quality. Underfloor heating also leaves the area being heated free from fixed appliances, affording more scope for individual room design. As a result of the Government’s commitment to the Kyoto Agreement for reducing carbon emissions, the Building Regulations have been tightened. Underfloor heating of all types is now recognised as being more efficient than radiator heating. Installation Electric underfloor heating basically comprises heat resistant cabling in spools that can be cut to length, spliced and laid as needed, or embedded in ultra-thin mats in ready-made lengths that can be easily and speedily installed. A self-regulating cable can sense other sources of heat, such as solar radiation, electrical appliances and lighting, and adjust its heat output automatically. One benefit is unlimited flexibility for moving furniture around, the position of which might influence the effectiveness of other sources of heat. Self-regulating cables are suitable for installation on all sub-floors and in dry or wet areas. The cable is laid in a thin layer of filler covering the floor base. No extra mesh is required, and the heating cable is connected to the mains through a junction box. The system can be made watertight when installed in the floors of bathrooms and other wet areas. The self-adjusting feature is enhanced by laying the cable in thermally insulated aluminium plates. These reflect heat upwards, leading to energy savings of 20% or more. The plates have grooves into which the cable is inserted. No filler is needed, and wooden or tile floors can be laid directly on top of the plate. It is a technique recommended for wooden or laminate floors in dry areas. Heating mats are eminently suitable for renovations, especially for tile floors. Ultra-thin (3 mm) and mounted with heating cable, they are available in ready-made lengths and are laid directly in a filler, on the existing sub-floor, whether wood, concrete or plastic. The mats are self adhesive. Attractive opportunities Because of its ease of installation, and the significant energy and cost savings benefit that can be achieved through the use of electric underfloor heating, it is a system that clearly provides attractive opportunities to the building-services engineer. Simon Broderick is trace-heating manager with Jointing Technologies, Unit 19, Woking Business Park, Albert Drive, Woking, Surrey GU21 5JY
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