solar water heater : certification:ISO9001,ISO14001,CCC,CE,Solar Keymark solar water heater:heat pipe tube pressure:pressuriz solar water heater: material:1.volume of storage ... water tank: insulating layer,polyurethane foaming ,thickness:55mm outer shell of tank,fluorin titanium plate,thickness:0.4mm inner ... foam with thickness 50-65mm,4.Suitable for campong area,holiday residences.5.no vent ...