solar water heater : certification:ISO9001,ISO14001,CCC,CE,Solar Keymark solar water heater:heat pipe tube pressure:pressuriz solar water heater: material:1.volume of storage tank:120L,180L,240L,300L2 ... ,structure,gradual change SS-AL-Nx/Cu,selective absorption coating5.frame:,aluminium 1.2mm thickness6.working pressure:normal working pressure:6bar ...