Water heating can be responsible for nearly 20% of a home's energy usage. Directly heating water with the sun's energy is far more efficient than making electricity with solar panels and then using electricity to heat the water. But the appearance of rooftop water heating panels can be a drawback for some homeowners. A new option is the Greenward ridge vent from Energy Alternatives, which uses the entire roof as a heat collector (something that your roof is already doing).
The idea of using the roof as a solar heat collector is not a new one. But the way Greenward does it makes it far easier to install and still get a significant benefit. Instead of having to thread tubes back and forth throughout the entire roof, the Greenward tubes are installed just at the ridge, which should be the warmest part of the roof due to the natural ventilation.
Since the Greenward ridge vent is like other ridge vents, where the final exterior appearance depends on using the same shingles as the rest of the roof, it isn't limited to a particular look. And, because the Greenward ridge vent is only installed along the ridge of the roof, it makes it an easy candidate for retrofit installations on existing homes.
Heated water from the ridge goes through a heat exchanger to store hot water in a tank. It can then be drawn directly into the hot water tank, as pre-heated water that needs much less energy before it is used or as completely heated water. For cold climate installations, the Greenward ridge vent should be filled with a water/glycol mix to prevent freezing damage.
Solar water heating generally offers one of the fastest payback periods of any green home improvement project. This should help make it much easier to incorporate an easy, efficient system into many more homes.
link: Energy Alternatives
written by johnatron, November 20, 2010
written by Asaf Shalgi, November 23, 2010
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