Friday, March 26, 2010

How Heated Floors Are More Energy Efficient than Central Heating - Part 2

Heated floors have been with us for thousands of years. Archeologists have discovered ancient Roman houses that had an arrangement for floor heating. These houses were discovered in the Roman city of Bath, in England. The floor had short pillars on which there was another solid flooring. The space that this created was used as a duct for heated steam or water to pass through. The heat from this conducted to the floor material - specially made from conducting material - and then radiated from the floor to warm the room. This was different from open hearth fireplace systems that relied on convection of heat through the air, a process that was inefficient and dangerous. The underfloor heating technology was known as hypocaust.

In our day, underfloor heating is a very useful method to keep a room warm in winter. It is widely used in many countries, and the technology uses steam rather than water, in most cases, because steam is usually hotter than water, and lighter too, so it is easier to manage. A boiler is kept outside the house, or underground, and various means are used to heat the steam therein. Then it is passed through specially created ducts, and this heats up the specially created floor.

The main reason the hypocaust technology was more efficient than central heating is that central heating uses convection. Convection is the process of heating up the air, which thereafter heats up the whole room. One problem with convection is that much energy is lost in heating up the air. Also, hot hair has a tendency to go upwards, so the upper parts of the room get more heat than the lower parts, where people tend to stay longer. Thirdly, some energy is lost is bringing the heat from the central area to each radiator in each room.

However, with floor heating, convection is not used, but radiation and conduction. Radiation is a much more efficient method of heating than convection; similarly, for conduction. The heat is conducted from the ducts with the hot steam, directly to the floor, which is made of special material that can efficiently hold and transfer the heat. Then the heat radiates from the floor directly upwards into the room. In this way, the room is heated bottom up, and it stays warmer at the expense of less amounts of energy.

Underfloor heating can save up to 40% of your energy costs from a central heating system. If condensing boilers or a solar power system is used the savings can be high. Especially in large houses with a lot of floor space, underfloor heating is very cost effective. If long pipes without any joints are used, there is absolutely no need for maintenance as well, and a pipe like that can last a 100 years or more. It is critical to use the best material, because repair can be difficult under the circumstances. However, even though the initial cost is higher than central heating, the savings can be substantial in the long run.

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