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Ancient Romans used under floor heating systems similar to those in use today. Instead of smoke, electricity or hot water is used in modern radiant space heating applications. Solar hot water systems are an excellent way to heat hydronic (water) radiant heating systems for houses, industrial, agricultural and commercial spaces. Solar Domestic Hot Water systems (SDHW) can be designed to meet not only the domestic hot water but also the space heating needs of the building/user. Combining the application of domestic hot water with space heating maximizes the year round benefits of the system.
Several types of radiant heating systems are used with solar hot water. Radiant floors are a common system used with solar hot water. Pipes are laid in a floor, usually with a concrete slab poured on top. The pipes connect to a manifold that separates different areas of the floor into zones for greater temperature control. The pipes, usually plastic PEX piping, contain a heat exchanger fluid, usually a propylene glycol mix, which circulates through a hot water storage tank heated by the solar hot water system. Alternatively, the pipes can be in the walls of a building or connect to radiators inside rooms. Less commonly, solar hot water systems can also be used to heat air with a liquid to air heat exchanger. Direct radiant hydronic heating of the floor, walls or radiators for space heating is preferred because of higher efficiencies and comfort. Temperatures required for radiant floor heating systems are lower than required for radiators, making it a good match for solar hot water systems. A radiant floor system under a tile floor can be as low as 32 to 40 degrees Celsius, whereas a baseboard heater requires temperatures up to 90 degrees Celsius.
The same solar systems used for domestic or commercial hot water use can be used for space heating. Either Glazed Flat Plate collectors or Vacuum Tube collectors can be used depending on the system design. A larger or separate storage tank can be used. As with any solar hot water system, the size of the collectors and storage tank will depend on factors such as the climate, solar exposure and amount of hot water required.
Components of a solar hot water space heating system, in addition to solar collectors, heat exchanger and storage tank(s), can include tank and pipe insulation, a circulation pump (AC or DC), PV panel (to run DC circulation pump), thermostatic controls, timers, connecting pipes, heat exchange fluid, collector mounting structure, filters, heat and flow meters, and pressure gauges. The radiant heating system includes pipes, manifolds, valves, thermostatic controls, heat exchange fluid and circulation pumps.
Modified: 02-13-2008
