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 tank:120L, ... polyurethane foam with thickness 50-65mm,4.Suitable for campong area,holiday residences.5.no vent and ... to low pressure model6.no wateris introduced into vacuum tube7.anti-freeze:using the anti-freezing liquid ...