... steel CCC,CE,SGS,ISO9001,Solar Keymark OEM service vacuum tube solar water heaterCCC,CE,SGS,ISO9001,Solar KeymarkInner tank: ... SUS304, 0.4-0.5mmOuter tank: color steel, 0.31mm Vacuum tube: common \three-target; 47x1500 \ 58x1800Bracket: Galvanized steel\Aluminum alloy ... depending on gravity water head.This system matched with vacuum tube solar collector. Water flow inside and complete a circulation ...