Warmth from below

Efficient and invisible, underfloor heating is finally catching on in the UK, says Hester Lacey

We British love our radiators. Or at least, we tolerate them. Radiators take up space and are uncomfortably hot if you get too close to them. They fill up with air and gurgle and rumble. They are ugly beasts, so we try to hide them behind fussy screens or paint them bright colours. But if you don't want to freeze, what's the alternative?

Most homes on the Continent stay toasty warm with underfloor heating, which is invisible, quiet, provides even heat and needs little maintenance. There are two basic types of underfloor heating: wet and dry. A wet system uses hot-water pipes underneath the floor surface and is powered by a boiler and pump. A dry system uses a mat of electrical cables that warms up in the same way as the wires in an electric blanket.

A standard radiator transfers heat from a small surface area, so has to get very hot – typically around 80 degrees Centigrade. But a floor is much larger, and only has to reach 26 degrees to keep the room above it warm. This temperature is below body heat, and the floor itself will barely feel warm to the touch: there's no question of hopping across a room-sized hotplate. "Radiators heat the air, which rises, so you're heating the ceiling," say Douglas Haigh, managing director of Begetube UK, the British arm of the Belgian wet-system specialist. "With underfloor heating, the highest temperature is down by your ankles, which is much more efficient."

Wet and dry systems can be used under virtually any kind of floor, but are particularly effective under "cold" finishes like tile, stone, wood, laminate or vinyl. The insulating effect of carpet tends to reduce the efficiency of an underfloor system.

If underfloor heating is so great, why doesn't everyone already have it? "When it was introduced here, the technology was not very advanced, and it has taken this long for customers to accept that today's products are superior," says Paul Frost of Underfloor Heating UK, which distributes dry systems by the Danish firm Devi. We are catching on fast, however – both Begetube and Devi are expanding rapidly in the UK.

Wet-system pipes need space, and Begetube is best suited to a new build or a complete refurbishment, says Douglas Haigh. He has installed systems in new homes and conversions, as well as in sports halls, office blocks and garages. A Begetube system is equally at home outside. "One chap had a steep driveway that got hopelessly iced up in the winter, so we laced some pipe in for him. Snow-melt systems are very common in Europe, the US and Canada."

Devimat lends itself more readily to retro-fitting, and is a simple DIY project. The cable matting comes in a roll and is self-adhesive. Once it's down, you lay the floor on top, and at 2.5mm thick it is unlikely to affect the height of the floor. You will, however, need an electrician to connect it, Frost says. He recommends those approved by the National Inspection Council for Electrical Installation Contracting. "It states that there must be an earth safety screen over the cabling, so if there is mechanical damage or water ingress, it trips immediately. Our cabling has a 10-year warranty, and the only faults we've ever had have been down to damage during installation; there are Devi floors that have been working for 40 or 50 years. If something does go wrong, there are tests that can pinpoint the problem to within four tiles."

Both wet and dry systems are low maintenance. A Begetube system is unlikely to spring a leak unless you accidentally drill through it, Haigh says. "The high-grade polyethylene pipes we use have a 50-year life based on continuous operation at 95 degrees and six-bar pressure, but the system usually runs at 50 degrees and one-and-a-half bar pressure, so they are very reliable."

Much of the cost of a wet system will depends on the area involved, he says. "There are real benefits from economies of scale. If you're fitting underfloor heating in a conservatory extension of, say, 12 to 15 square metres, it will cost £32 per square metre; if you're fitting out an aircraft hangar it will be £6 or £7 per square metre. Everything else falls between those two extremes." And running costs are low – around 2.4p per kilowatt/hour on gas or oil.

A Devimat kit to heat a 5sqm concrete floor costs £304.96 plus VAT. An electrically heated floor can be expensive to run, but the most efficient control systems can charge the floor with heat during off-peak hours when electricity is cheaper, then use the stored heat throughout the day.

So, what about those radiators? Douglas Haigh is rather scathing about the poor things. "Imagine if underfloor heating was the norm, and everyone had an invisible, safe, efficient method of heating their homes. Then someone comes along and says, 'I've invented a new form of heating! It's a large, heavy, sharp-edged piece of hot metal and you have to hang one on the wall in every room in the house.' How many do you think they would sell?"

Underfloor Heating: 01473 280111, www.electricunderfloorheating.co.uk; Begetube: 01463 831560, www.begetube.co.uk