Tuesday, 15 June 2010

Underfloor heating

Despite the best efforts of designers to produce attractive radiators, our homes undoubtedly look better without them. The popularity of underfloor heating is primarily driven by our desire to liberate our walls from these imposing lumps of metal. By turning the entire floor into one big radiator, underfloor heating puts the heating system in its place: in touch but out of sight

Water vs. electricity
Most underfloor heating systems use hot water supplied by a boiler or other heat source. The water is pumped around all the floors of your house in exactly the same way that it is pumped to radiators.

Some underfloor heating systems use electicity to provide the heat instead. These are easier to install than wet systems, but are not at all eco-friendly. Electricity is the dirtiest and most inefficent domestic fuel because so much energy is lost in the power station. It should only be used for heating as a last resort. Electrical systems are also much more expensive to run.

Efficient and effective
Because radiators are relatively small, the temperature of the water that flows through them has to be kept quite high in order that enough heat can be released into the rooms of your house to keep them warm. As underfloor heating uses a much larger surface area to emit heat, it can run at a lower temperature. As modern condensing boilers run more efficiently at lower temperatures, this difference makes underfloor heating a greener choice. But only just: don't rip up your radiators and install underfloor heating for this reson only.

Underfloor heating is also more effective in delivering heat to where it is needed. Radiators create currents of air that take the heat to the top of the room, where we need it least, and create draughts of cold air at floor level. Underfloor heating is more comfortable because it radiates heat gently across the whole room. There are no hot and cold spots and no currents of dry, dusty air. Rooms with warm surfaces and stable air do not require the high air temperatures of radiator-supplied rooms: you may be able to turn down your thermostat, save energy and still be more comfortable 

Not for everyone
Small lumps of metal heat up very quickly; concrete or timber floors do not. The big disadvantage of underfloor heating is its sluggishness. If your home is cold and you want to heat it up rapidly, underfloor heating will not do the job. Underfloor heating works best with well-insulated, energy-efficient homes that do not lose heat quickly and stay at a fairly stable temperature across the day. It is therefore most suited to constantly occupied homes.

Underfloor heating can also exacerbate overheating problems. If you have rooms with a lot of glazing that heat up quickly when the sun comes out, you will be in trouble if your floors continue to emit heat long after the heating system has been switched off. Such problems can be avoided by reducing the risk of overheating with good shading.

Floor finishes
Underfloor heating can be used with any floor finish, but solid floors of stone or tile are best. Underfloor heating can be laid beneath timber floors as long as the timber is dry. Existing floorboards in centrally heated houses will be suitable, but new timber floors should be given time to acclimatise to the building first. Avoid fitted carpets as these act as insulation and slow down the heat flow to the room. On ground floors insulation must be laid first or you will simply heat the ground.

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