... vacuum tubes and spare parts for free Heat Pipe Solar Water Heater Specification:inner tank: food grade sus304-2B stainless steel, 1 ... -80 hourshail resistance: 25mmOptional: heat exchanger (red copper), electric heater (1.5kw, 2kw, 2.5kw, 3kw), assistant tank( 5L, 8L, 12L, ... 15L), magnesium barFeature:Working with high pressure, so do the water it ...