 |
Solar water heaters, or geysers as they are referred to in some parts of the world, come in five basic designs. Passive systems are the simplest and do not have any mechanical parts. Active solar water heaters use pumps and valves. Open loop systems heat the water directly, while closed loop systems are indirectly heated using a heat exchanger. It is important to determine the specific needs of each household when designing a system, including climate and the number of people who will use the hot water, plus the time of day when it will be most needed.
- Consider the climate in which your design will be used and the number of people who will use the hot water. Solar heating systems use a collector made up of a collector plate coated with absorber coatings and metal pipes -- called risers -- for the water to run through and become heated. The collector is usually flat and insulated with a glass front. You will need to include tanks, pumps, valves, pipes and fully assembled collectors in your design.
- Draw a batch design. This is simplest and oldest warm climate solar heater type. Batch solar heaters have one tank, the collection tank, performing two tasks: collection and storage. The collection tank for a batch system is usually a square box that is insulated and has a glass panel on the front. The box is mounted on the roof or other sunny area. The system is plumbed so that potable water enters the bottom of the collection tank, the sun heats the water and the warm water stays in the tank. When a faucet is opened in the house, the warm water is drawn out of a pipe at the top of the collection box and more cold water fills the collection box. You may add an electric backup tank to your design, which would be mounted in your home and would heat the water when it is not heated sufficiently by the sun. Do not install in freezing climates.
- Design a thermosyphon hot water system. These are the most commonly used solar heating systems in the United States and around the world. The cold water runs through the bottom of the solar storage tank and into the flat plate collector. Thermosyphon systems rely on the fact that hot water rises and require no pumping to move the water through the collector to the backup water heater in the house. You need to add an isolation valve on the incoming cold water pipe and the outgoing hot water pipe plus a tempering valve to mix cold into the hot water when necessary. This design is not suitable for freezing climates.
- Plan an open loop direct pump solar heater design. This is similar to the passive designs but with a pump to circulate the water and the holding tank is mounted in the house beside the backup tank. The water is pumped through the collector and back into the holding tanks and does not lose as much heat at night because it is indoors. You will need three isolation valves and a tempering valve plus a 10-watt pump and its control panel. This design is suitable only for warm climates.
- Draft a drainback water geyser design. This allows the water to drain out of the collector into a drainback reservoir tank mounted beneath it and above the storage tank. The pump passes the water up through the collector then through a heat exchanger before it goes into the storage tank. A differential thermostat control drains the water out of the plumbing loop when the temperature drops, thereby preventing it from freezing and damaging the risers. This system uses distilled water and requires very little maintenance. It can also be designed to use antifreeze solution, although this has to be changed periodically. A stronger pump is required to move the water through the system.
- Design an antifreeze solar water heater or pressurized glycol design. This is the best option for very cold climates. It uses antifreeze mixed half and half with water, which is pumped through the collectors. The water is heated by transfer when it makes contact with the heated pipes. This design requires more plumbing to include an expansion tank, because the antifreeze expands when heated.
By: Trish Jackson
Article Source: ehow.com
Back to Solar Geysers Articles & Resources
|
|
 |
