solar heat collector with SOLAR KEYMARK,CE,ISO,SGS Solar heat collectorMaterial:Header tube: seamless copper TU1, 22×δ1.2mmFlowing ... , δ40-50mmVacuum tube: tri-elements coating, copper heat pipe inside, 58×1800mmCopper heat pipe: δ0.6mmLogo: OEM stickerSpecification: 15/20 ... thermal collector (by vacuum tube with copper heat pipe inside or flat panel) gathers heat energy from sunshine and transfers to ...