• Solar water heaters are very cost-effective.photo Solar energy image by Aleksandar Radovanovic from Fotolia.com
  
  Solar water heaters can be a very effective way to save money while generating hot water for your house. You purchase the heater itself, but to use it is completely free, so you can earn your money back and then some. They consist of storage tanks and collectors. There are two main types of solar water heaters. The first being active heaters that use circulating pumps and controls. The second, passive heaters that do not use either of the above. It's almost always required that you have a backup system for your solar water heater due to cloudy days and times when you need to use it more.
  
  

Direct Circulation Systems

• Direct circulation system solar heaters work the best in climates that seldom gets cold enough to freeze. This system directly circulates water from the cold intake through the collector where it is heated and sent back to the insulated storage tank by the use of controllers. A valve opens on its own where the cold water is then pumped through the collector.
  
  

Indirect Circulation Systems

• Indirect circulation solar water heater systems are best for climates that have more freezing temperatures. The pump circulates a heat-transferring fluid through the collectors and to the heat exchanger. The water is then heated that goes into the home. They can also use non-freezing fluid to ensure the fluid in the water heater is constantly moving. Indirect systems require more gadgets, making them a higher cost than direct circulation systems.
  
  

Integral Collector-Storage Passive Systems

• These solar water heater systems are best used in climates where freezing seldom occurs. They are good for homes that use hot water often during the day and evening. Cold water passes through the collector, the hot water storage system, where it is then warmed by the sun. Hot water is then taken from the top, where it is the hottest. There are no controls or pumps needed for this system, making it very easy to use.
  
  

Thermosyphon Systems

• Thermosyphon system is a type of solar water heater. Warmer water rises while cooler water sinks, and causes water to flow through this system. The collector is installed underneath the storage tank, where the warm water will rise to. When installing one of these systems it's imperative to pay close attention to the design of the roof because the storage tank is very heavy. The water contained in the collector is heated, making it expand thus becoming lighter than the cold water held in the tank. Gravity then pulls down the cold water from the tank to the collector. The cold water moves the heated water to the collector and into the tank's top, where it is then heated. There are no pumps or controllers required for this system. A cold water line directly hooks to the tank. The water heated then flows from the tank atop the roof into an auxiliary tank installed on the ground where it is used inside the residence.This system features a thermally operated valve that protects the collector from freezing. It also includes isolation valves, which allow the solar system to be manually drained in case of freezing conditions, or to be bypassed completely.