Thermosyphon tubular Solar energy water heater 
There are two basic types of solar water heaters: Passive & Active. Active systems utilize a circulating pump and some type of temperature control. Passive systems do not have any moving parts and rely on the basic principle of physics-that hot water raised & cold water falls.
Active systems all function basically the same, however, there are different configurations (closed loop and open loop), depending on your climate zone. Passive systems come in two basic types: Thermosyphon & Batch. Each system has its distinct advantages.
Active systems use electric pumps, valves, and controllers to circulate water or other heat-transfer fluids through the collectors. They are usually more expensive than passive systems are generally easier to retrofit than passive systems because their storage tanks do not need to be installed above or close to the collectors.

The thermosyphon solar water heaters relies on
the natural circulation of water between the collector and the tank or heat exchanger. As water in the vacuum tubes is heated it rise naturally into the tank, while cooler water in the tank flows down to the bottom of the vacuum tubes, causing circulation throughout the system. The following picture is the simplest of installation configurations for the thermosyphon tubular solar water heater. The tank is low pressure, open vented. The tank is manually filled by opening a tap in the house. Once the tank is full water runs out through an overflow pipe which is fed back down into the house. When water starts flowing out the tank is full. When using water the tank gradually drains until it is empty. Once accustomed to the method of operation, the user knows how much water is left in the tank and can fill it up at the appropriate time. Depending on hot water usage pattern and weather conditions, the hot water can be used directly for showering, or can be used as a pre-heat, feeding the inlet of an instant or tank water heater.
 Content:
1. Outer tank material: galvanized steel plate, stainless steel. Galvanized iron sheet, color steel plate.
2. Inner tank material: SUS304-2B Stainless steel plate of food grads.
3. Inner tank insulation layer: 40-75mm integrate foamed polyurethane.
4. Support material: shaped aluminum alloy, stainless steel, plastic coated circular steel tube, electrophoresis aluminum alloy.
5. Normal water temperature: 45-95℃
6. All-glass evacuated solar collector tubes, thermal transfer rate≤0.022W/m.K, outer diameter: 47mm/58mm/70mm. Length:1.5m, 1.6m, 1.8m, 2.0, 2.1m
7. Water volume( liter): 100—300
8. Packing: carton.
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