Thermosyphon solar water heater 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 rises naturally into the tank, while cooler water in the tank flows down to the bottom of the vacuum tubes, causing circulation throughout the system. Technical specificationa *Both of inner and outside water tank shell are made of SUS3042B food grade stainless steel plates, welded by argon arc. Water is pure and drinkable. *Heat insulation of water tanks adopts polyurethane foam, thickness is 55mm. *Silicon rings to connect and seal them. *The tubes and supports are adjustable, power bearing is average, and can assure the vacuum tubes to use for long time. *Whole glass vacuum tubes adopt super hard borax and silica glass. *Absorb rate:=93%, thermal radiation rate:=6%(100 íµ) *Resist 25mm hail, using life can last 15 years. *Temperature when exposed to sun without water:250íµ, 2.5hours to boiling if using single tube. *If you use electrical appliances to aid heating, to switch off the power supple before boiling. *To test the water temperature before using, in order to avoid scalding.