Solar Water Heating System 1) CE, ISO9001,CGC certificate; 2) easy operation and fashionable; 3) high efficiency. 1)Inner water tank shell all are ... drinkable. Inner tank thickness is 0.4mm, the highest thickness for SP-R direct insert lower pressure can be 0.8mm ... thickness Galvanized Steel or 201 steelStructure of tank:4 holes for exhaust port, overflow, water inlet and outlet, electric heater is ...