Characteristics This type uses the all–glass evacuated solar tubes as the heat-absorbing element. The high vacuum closed cavity between the outer and inner tube reduces the heat emission which is caused by convection and conduction. The layer films(coating) of the all-glass evacuated tubes transfer the sun energy into heat energy. The high absorption and low emittance rate of Jiadele’s layer films is unique. Depending on the different density between hot water and cold water, a water flowing cycle is created in the tube. Hot water flows automatically upwards while the cold water flows down. The water in the storage tank will be heated by this natural circulation. Material: ***** tank:stainless steel SUS****2B, 0.4 OR 0.5mm 2. Vacuum tube: QB-AL-N/AL or AL-CU/SS Coating, size: ******0, ******0, ******0, ******0, ******0, ******0 ect. 3. Outer tank: painted steel*0.*5mm/aluminum-zinc coated steel*0.*5mm; stainless steel SUS**4, SUS**2 ect. 4. Frame: coated galvanized steel*1.5mm; AL-alloy steel, 2.*0mm; 5. Material of insulation: polyurethane