... for hot water 3.certification pre-heated solar water heater with assistant tank Working principle:Pre-heated solar water heater also ... color steelCapacity:100L,130L, 150L, 200L , 250L,300L;Tube: Advantages: with all-glass co-axial double tube, glass of High borosilicate ... can purify the water),so it can supply hot water with high quality, clean and even drinkable.2.And as copper coil ...