... 4.Unpressurized,more safe DEAKON unpressrized vacuum tube solar wate heaters Products features: 1, Modular design, ... 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 ... .90162 Vacuum tube stainless steel solar water heater