Install a Solar Water Heater
This is one of the best ideas for a solar water heater to come along. It’s based on the Breadbox heater, developed by solar pioneer Steve Baer, of Zomeworks in New Mexico.
Its main strength is simplicity. It’s really little more than a box with a glass front and top, insulated all around, including hinged insulated top and front. During sunny weather, the hinged covers are opened to let the sun into the box; there it strikes a couple of old water tanks painted black.
Unlike most other solar heaters, this one heats the water directly, right where it is stored. There are no pumps, thermostatic controls or long runs of pipe – nothing to break down or malfunction.
There are two ways you can use a heater of this type. For a simple summer vacation home, you could mount it up on the roof. Then gravity could feed the hot water directly to wherever you wanted to use it. You’d leave the cover open all summer, then drain the tank and close the heater down for the off season to prevent freezing.
For use in a year-round home, you’ll want to handle things a little differently. First of all, you probably wouldn’t use the hot water directly. Instead, you’d feed it to your conventional water heater. If conditions are favorable and the solar water is hot enough, your conventional heater’s thermostat won’t turn on, and the water will be heated for free.
If conditions aren’t so favorable, the water may need a boost from the conventional heater, but you’ll still save money by prewarming the water and reducing the load on the conventional heater.
Another difference between a summer and an all-season installation? In an all-season home, a rooftop location wouldn’t be so convenient. During cold weather, you want easy access to the heater so you can close the covers during the night or during long periods of cloudy weather. This makes a ground-level location more appropriate.
An ideal spot would be right against the south wall of your home, facing the sun. This would keep your plumbing runs short, and the back face of the box would automatically be insulated by the wall of your home.
For greatest efficiency, the heater should contain two small tanks (say about 30 or 40 gallons each) rather than one big one. In use, cold water is fed into the bottom of one tank. As it is warmed, it rises to the top of that tank. A short pipe running from the top of the first tank then feeds the water to the bottom of the second.
As the water is warmed even more in the second tank, it rises and can then be drawn off the top of that tank for use in the home. This delivers the hottest water to your home.
What about freezing? Obviously, this type of heater is at its best in a warm, sunny climate. Even so, it is unlikely that the water in the tanks would freeze except in the coldest climates . . . as long as the box is well insulated, and you remember to close the covers when necessary.
However, water in the pipes leading to and from the box can freeze, unless insulated and, in some cases, wrapped with electrical heat tape. That’s why it’s best to locate the heater right up against your home so you can run your pipe right out through the back of the box without passing through the outside air.
For maximum efficiency, line the inner faces of the two hinged covers with a reflective metal surface. Then you can aim the covers to reflect the sun onto the tanks, effectively increasing the collection area of the heater at little extra cost.
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Tags: passive solar water heater, residential solar water heater, solar heaters, solar hot water heaters, solar water heater, solar water heater panels