... water heater 1,Work longer hours 2,Economical and high-efficiency 3,Modular design and auto-operation 4,Multifunction Solar water ... heating ect.4.Work longer hours,low cost and high-efficiency. Material of model:a, The pipeline is made of red ... -2B materiald, Glass vacuum tube: new trivalent element heat tube, borosilicate glass 3.3e, Heat pipe: anti-freezing >-35°Cf, Water capacity:150L ...