Dip Into Solar Water Heaters

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Apricus Solar provided solar-thermal panels for the Cranberry Ridge LEED Platinum home in Freeport, Maine.
Apricus Solar provided solar-thermal panels for the Cranberry Ridge LEED Platinum home in Freeport, Maine.
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Heliodyne determines which type of system is best for a given home based on location, number of household members, water quality and more.
Heliodyne determines which type of system is best for a given home based on location, number of household members, water quality and more.
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Apricus Solar provided solar-thermal panels for the Cranberry Ridge LEED Platinum home in Freeport, Maine.
Apricus Solar provided solar-thermal panels for the Cranberry Ridge LEED Platinum home in Freeport, Maine.

More than 100 years ago, William J. Bailey patented the first solar water heater, the Day and Night. Relatively affordable and reliable, the heaters were a lot more efficient than cooking a big pot of water on the woodstove. In the United States, solar water heaters were eventually eclipsed by gas and electric water heaters, but in other countries solar water heating technology, also called solar thermal, thrived. Now seeing a U.S. resurgence, solar thermal is one of the simplest and most-efficient means of saving energy, says John Perlin, co-author of A Golden Thread: 2,500 Years of Solar Architecture and Technology (Cheshire Books, 1980).

System specifics for solar water heaters

Solar water heaters can use either a closed-loop or an open-loop system. In a closed-loop system, rooftop solar collectors heat a nontoxic antifreeze mixture. Once heated, the mixture is pumped to a heat exchanger–or solar tank–through copper tubing, where it heats cold water for use. An open-loop system works similarly but uses water instead of the antifreeze mixture.

Closed-loop systems use less energy and are better suited for houses in which the building configuration requires pipes to be laid flat. It’s crucial that a closed-loop system be appropriately sized for the household–a too-large system results in unused fluid that can damage the system’s mechanics. Open-loop systems heat efficiently and don’t need to be sized as specifically as closed-loop systems, but they require a drainback tank and use more energy moving fluid.

Types of solar water heaters

  • Published on Dec 15, 2009
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