Non-pressurized Solar Water Heater 1.For 5 years warranty 2.For 2% free spare ... 4.OEM service Working Principle Of Non-pressurized Solar Water Heater: This system uses the thermosiphon principle, Solar vacuum tube is pluged into the bottom ... : 15 degree, 20 degree, 25 degree, 30 degree, 38 degree, 45 degree, 51 degree ModelLigthing(m2)Vacuum TubeSupply hotwater(L/D ...