... tubes are broken 3.CE, ISO,CCC,ROHS vacuum tube U pipe solar collectorTwo heat exchanger models can be used for houses ... : 80-500L- Evacuated tubes: dia. 58mm*1800mm/850mm with heat pipe/U pipe- Insulation layer thickness: 50 mm- Bracket: galvanized steel with thickness ... , also we can produce any type according to customers requirementHeat pipe solar collector U pipe solar collector