Pressurized solar water heater 150L Solar keymark, CE, ISO Red copper heat pipe, transfer ... use, the hot water comes out because of water pressure, vacuum tube absorbs solar energy, and conductive copper pipe transfer the ... steelOuter tank0.4mm thickness colour coated steelInsulation LayerMaterial55mm thickness high pressure polyurethaneFoaming density35g/cm3Closed-cell foam rate95%Heat preserve72 ...