... 4,Anti-freezing -40 degree Newest heat pipe split pressurized solar water heater(CE,SABS,Keymark,EN12976)Technical data Heat Pipe ... The flow passage is inner closed and pressurized, no water or medium goes through glass vacuum tubes, no freeze to ... slope roof or flat ground or upright walls, almost maintenance free collectorWarranty: 5 years international responsibility for solar collector and ...