Heat below your feet

The Romans invented under-floor heating and it's back in fashion. Nicole Swengley discovers a cool way to dispense with those ugly radiators.
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The Independent Online

Stepping out of bed on to a warm stone floor is an affordable luxury that European homeowners have enjoyed for years. Under-floor heating (UFH) accounts for more than half the German heating market.

Stepping out of bed on to a warm stone floor is an affordable luxury that European homeowners have enjoyed for years. Under-floor heating (UFH) accounts for more than half the German heating market.

Here the figure is only 2.5 per cent yet sales are set to double by 2008 and some industry pundits believe that all homes will eventually be heated this way as homeowners finally realise that under-floor heating is not only comfortable and convenient but cost-effective too.

Up to now the revival of this historic concept has been driven mainly by aesthetic considerations. Everyone loves stone floors and tiled bathrooms but they don't like chilly feet. Nor do they want the sleek lines of flexible, open-plan living areas cluttered by bulky radiators. So why haven't we embraced UFH wholeheartedly when the Europeans have had radiator-free walls for years? Because electric UFH, introduced in the 1970s, proved costly to run and inconsistent - rooms were either too hot or too cold. Happily, today's technology eliminates these problems.

UFH systems are available for most kinds of flooring including timber, stone, ceramic tiles or carpet. Water-based "wet" systems use hi-tech plastic pipes set within or just below concrete or timber floors. These connect to the home's hot water boiler (gas, electricity or oil-fired) and warm the room via radiation so the heat is partly reflected by surfaces and partly absorbed. These systems are best-suited to larger refurbishments or new-build projects and need specialist installation.

"Dry" systems use electric cables or mesh mats. Systems with thicker cables bedded into the screed are suitable for any type of floor-covering - stone, timber or carpet - and require specialist installation. But if you've got a smaller area - a bathroom, kitchen or conservatory - with a stone floor or ceramic tiles then you could use new-style 2mm thin electric cables or a mesh mat wired into the mains power supply. These types of UFH don't require specialist installation but do need a competent electrician.

"The new electric systems are good for smaller areas with stone or tile flooring," says Jack Glendinning, the managing director of the under-tile heating specialist, Warmup. "You can also run them in tandem with wet systems using the latter for ground floor rooms and electric under-tile heating upstairs."

The key advantage of any UFH system is that heat radiates evenly from the floor upwards, allowing the room and furnishings to warm the air so there are no cold spots. The ambient temperature is palm-warm - about 25 to 28 degrees centigrade - and can be controlled by individual room thermostats and time-switches. In contrast, radiators warm a room via convection from the ceiling downwards - much of it in wasted space above your head - causing stuffiness and draughts.

Wet UFH systems operate at much lower temperatures (45šC) than conventional radiators (85šC plus) to achieve similar levels of warmth and, unlike radiators, are designed to stay on throughout winter so less energy is needed to run them in a properly insulated house. This is a significant consideration given that fossil fuel consumption is likely to become more expensive in the future.

Most UFH systems require very little maintenance and there are other benefits too. Heat-loss through windows, ceilings and walls is considerably reduced. This is particularly important in properties with high ceilings such as loft apartments or barn conversions. Less dust wafts around the room resulting in less cleaning and UFH is safe for children and elderly people as there are no sharp edges or hot surfaces.

The installation of wet systems or thick-cable dry systems is inevitably easier in new-builds than old houses. But if you are intending a major refurbishment then the disruption could be worthwhile.

It's essential to use a company specialising in domestic heating (check out the Underfloor Heating Manufacturers' Association website) for all but the simplest electric systems.

Most wet systems are made bespoke (pipes should carry the British Standards Institution's kitemark conforming to BS7291) and manufacturers will need detailed room plans before designing a system that takes heat-loss into account.

The cost depends on various factors. An old, poorly insulated house requires more piping than a well-insulated property. Florad, which has supplied wet systems for more than 20 years, charges around £16 per square metre for screeded floors (around £30psm for timber floors). This includes design, supply and manifold (control unit) but excludes VAT and installation.

Electric systems may seem cheaper to buy but can be more expensive to run. An average-sized bathroom (3m 2) fitted with Warmup's BEAB-approved system costs £180 including VAT. The Devimat, a self-adhesive mesh carrying electric heating cables made by DEVI Electroheat, costs £200 plus VAT for a 3m 2 bathroom excluding fitting and electrician's costs.

It's worth comparing information from several companies and shopping around for quotations before you finally start toasting your toes.

Underfloor Heating Manufacturers' Association: www.uhma.org.uk