... water 3.certification pre-heated solar water heater with assistant tank Working principle:Pre-heated solar water ... also works at 0.2MPA. Necessary parts: Tank( with a copper coil inside) ,the three-high vacuum ... 130L, 150L, 200L , 250L,300L;Tube: Advantages: with all-glass co-axial double tube, glass of High ... power,and heats the water faster compared with normal tube coated with AL/N/AL Number of the ...