SOLAR HOT WATER Erica Mevs DFN 2004

Origin The shallow water of a lake is usually warmer than the deep water. The sunlight can heat the lake’s bottom in the shallow areas, which in turn, heats the water. It's nature's way of solar water heating. The sun can be used in basically the same way to heat water used in buildings and swimming pools.

Main parts Most solar water heating systems for buildings have two main parts solar collector storage tank.

There are three primary types of solar systems collectors : batch collectors, flat plat collectors evacuated tube collectors. Each has specific advantages and disadvantages depending upon the climate you live in and the demands you have for hot water. Collectors

Batch Collectors Batch collector systems are very popular in tropical or warm climates. They usually consist of one or more water tanks that sits on your roof instead of your basement or garage and they use the heat of the sun directly to warm the water. Most batch systems use one or two hot water tanks of between 20 and 40 gallons Batch type solar water heaters tend to be used only in warmer climates because they are susceptible to freezing If you live in a very warm climate such as California or Arizona, you can actually find that batch type collectors can heat the water to too high a temperature (over 160 degrees Fahrenheit). In these situations you might also need a mixing or tempering valve which allows the overly heated water to be mixed with cool water in order to obtain an optimal temperature.

Evacuated Tube Collectors water or another fluid flows through a collecting device (manifold) carrying the heat to the hot water tank. Unlike flat- plate collectors, they don't let as much heat escape back out again, so they're more efficient. Evacuated tube collects are the newest of the technologies for collecting hot water. Evacuated tube collectors consist of a series of long transparent glass tubes. Inside each tube is a copper pipe called the absorber tube. The absorber tube is covered with an absorbent material to collect the heat from the sun. An evacuated-tube collector

Flat Plate Collectors The most common collector is called a flat-plate collector. Mounted on the roof, it consists of a thin, flat, rectangular box with a transparent cover that faces the sun. A flat-plate collector

How it works 1. Sun heats water flowing in a circuit through the collector. Small tubes run through the box and carry the fluid to be heated. The tubes are attached to an absorber plate, which is painted black to absorb the heat. As heat builds up in the collector, it heats the fluid passing through the tubes

Systems that use fluids other than water usually heat the water by passing it through a coil of tubing in the tank, which is full of hot fluid. 2. The water leaving the collector is hotter than the water entering it and carries its heat toward the water tank. The more people in your household, the bigger the tank you'll need. A typical tank for a family home might be about 100– 200 liters (30–60 gallons).

3. The water doesn't actually enter your tank and fill it up. Instead, it flows into a pipe on one side of the tank and out of another pipe on the other side, passing through a coil of copper pipes (the heat exchanger) inside the tank and giving up its heat on the way through.

Solar water heating systems can be either active or passive Solar water heating systems can be either active or passive 1. Passive solar hot water systems are probably the oldest commercially available solar system. The United States Department of Energy defines passive solar heating as a process that uses the windows, walls and floors of a building to collect the sun's heat. Passive solar heating doesn't require any mechanical devices such as fans, pumps or electrical controls.

2.Active solar heating, on the other hand, includes mechanical devices. Active solar devices are often designed to heat air or liquid, then pump or fan the heat to a specific area in a building. Active systems rely on pumps to move the liquid between the collector and the storage tank, while passive systems rely on gravity and the tendency for water to naturally circulate as it is heated. The active solar system also has a controller, for the winter

“zero-energy home” A zero-energy home is a home that produces its own energy, meaning that there is no energy bill. Zero-energy homes combine passive solar architectural designs with active solar heating and water systems---as well as solar electric systems---to create a living space that depends only on sunshine for light and heat.

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