Deno Compact Non-pressurized Solar Water Heater with high quality 1. CE ,ISO CCC 2. 5 ... complete system doesn't need any power, green and economic.4. Easy install, easy operation, fashionable. ... 5. Well wind, snow and hail resistance.6. 72 hours heat preservation.Working Principle ... thermosiphon principle, the hot water rise up, and arrive in the water tank, the cold water ...