... solar water heater 1.CE,CCC,ISO9001 certificate 2.heat pipe 15 years warranty 3.delivery:15 days 4.OEM split pressure solar water heater ... 1. that type have CE,ISO9001,CCC, certificates, completely guarantee high quality,2. each tube inside have copper ... 25mm, work principle the water tank have coil,connect with the solar energy, inside coil have special liquid for recirculate ...