... Diameter 16mm 25mm Good price, strong warranty 100-750L Storage water tank with heat exchanger1. Inner tank: 1.5-2.0mm ... design to tech support......3. Various certificates: ISO, EN12975, EU CE, Solar Keymark, Kang-Ju, KOLAS, SABS, SRCC4. Strong warranty: ... long and good business relationships, our company have strict quality control and aftersale service. Storage hot water tank with heat exchanger