... heating efficiency 4.Unpressurized,more safe DEAKON unpressrized vacuum tube solar wate heaters Products features: 1, Modular design, arbitrary combination,harmonize ... tube: new trivalent element heat tube, borosilicate glass 3.3.e, Water capacity: 100L,150L,200L,300L,360L, non-pressurized water ... -303.84581800302802.30142DK5818-364.6581800363502.90162 Vacuum tube stainless steel solar water heater