Date: 11-27-00
DEVELOPMENT REPORT - Solar Water Heater
By Gary GarriottThis is the VOA Special English Development Report.
Solar water heaters are devices that use energy from the sun to heat water. Solar water heating is used around the world. The solar water heater described here was first designed and developed in Afghanistan more than thirty years ago. Since then, it has been built and used in many countries around the world. It can heat seventy liters of water to sixty degrees Celsius. It can do this between sunrise and noon on a clear day with an average outside temperature of thirty-two degrees Celsius.
There are two parts to the solar water heater. One part is the solar collector. It is made of metal sheets. Black-painted surfaces that receive the sun's heat become hotter than those of any other color. A metal surface painted black and placed in contact with water will heat the water. The black metal plate is called a collector. There are several kinds of metal sheets that can be used for the collector. Metal sheets that have raised sections will work very well. These corrugated sheets often are used to make the roofs of houses.
Once the water is heated, it is kept hot with material called insulation. This allows the water to stay warm for a long time.
The second part of the solar water heater is a container called a storage tank. It holds the water for the system. The tank can be a container that holds about one-hundred liters. Two rubber pipes are attached to the water storage tank. One pipe lets water flow into the system. The other lets water flow out.
When the water heater is working correctly, water will flow from the storage tank to the collector and back again. You can use the hot water at the top of the tank for washing and cleaning. You can change the flow of water so that the temperature is hot or warm as desired.
This solar water heater is easy to build and operate. It will last about two years before the rubber pipes need to be replaced. However, it will heat water only on sunny days.
You can get more information about solar water heaters from the group Volunteers in Technical Assistance. You can contact VITA through the Internet at www. vita. org. Or you can write to Special English, Voice of America, Washington, D-C Two-Zero-Two-Three-Seven, U-S-A.
This VOA Special English Development Report was written by Gary Garriott.
Source: www.voa.gov/special/