Solar water heater:
Solar water heater uses radiation from the sun to heat up water. Solar water heater does not consume any fuel so it is used in developing countries where fuel is relatively expensive but sunlight is abundant.
Parts of solar water heater:
The solar water heater consists of the following parts:
- The solar collector in which water is heated by solar radiation.
- An insulated storage tank in which the heated water from the collector is stored. The storage tank must be put higher than the top of the collector.
- An insulated pipe connecting the lower part of the collector and the upper part of the storage tank.
- An insulated pipe connecting the lower part of the storage tank and the bottom of the collector.
- A cold water inlet connecting an existing water supply system to the storage tank. Usually the cold water inlet runs via a buffer tank with a floating gauge.
- An insulated hot water outlet running from the storage tank to the top.
- A vent (air escape pipe) to prevent over pressure cause by air or steam.
Working of solar hot water system:
When solar radiations heats the collector, the water inside will be heated as well. The heated water starts rising through the connection on the top of the collector to the insulated storage tank. Heated water entering the storage tank displaces cooler water that is in turn forced via the connection to the bottom of the collector. In this way, a circulation comes into being. We call it thermosyphon principle.
The cold water entering the collector will be heated again by the solar radiation. Because the water temperature inside the collector becomes much higher than inside the storage tank, the natural circulation continues as long as the sun heats the collector. Consequently, the water inside the storage tank will get hotter and hotter. Depending on the amount of solar radiation and insulation, the system can produce water temperatures between 40°-70°C.
Use of hot water systems:
If we want to use the hot water in the storage tank, we have to tap it. When hot water is tapped, the storage tank must be refilled. Therefore, the storage tank is connected via a buffer tank to an existing water supply system. The buffer tank is provided with a floating gauge or ball valve. When tapping a bucket of hot water, the system will be refilled automatically via this floating gauge.