... -efficiency 3,Modular design and auto-operation 4,Multifunctio Solar water heater features:1.Modular design, arbitrary combination,harmonize with the building ... heating ect.4.Work longer hours. Material of model:a, The pipeline is made of red copper and conducted by heat transfer ... uses 50mm polyurethane foam and has a good effect of temp. preservation.c, Water tank: All SUS-2B d, Glass vacuum tube ...