... heat tube, borosilicate glass 3.3.e, Water capacity: 100L,150L,200L,300L,360L, non-pressurized water tank.f, Heat preservation: 72h~80h, 50mm ... polyurethane foam inside water tank. ModelGross absorber area(sqm ... -303.84581800302802.30142DK5818-364.6581800363502.90162 Vacuum tube stainless steel solar water heater