... instant water heater 1. 5 years warranty 2. CE,SRCC,SGS,Solar Keymark,ISO9001:2008 This is a kind of solar water ... . This working principle of solar water heater is make it natural circulation between the water tank and the collector pipe . ... to run continuously to heat the water tank.Solar energy instant water heater features1. Conventional domestic solar water heaters,Looks beautiful2. Easy plug ...