solar collector for thermal system split pressure solar water heater system , it's easy for installation and using Specification:1) ... 1,800mm, Φ70 x 2,100mm2) Vacuum tube size: 15, 16, 18, 20, 24, 26, 28, 30, 363) Automatic controlling system ... temperature preservation can last 72 hoursPacking:Carton Solar Energy Water Heater Project , solar collector