... -80 hours hail 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 produces.It uses the ... still work in the event of occasional tube breakage. Parameter Compact Pressurized Solar Water Heater