Heat pipe solar collector is Solarkeymark approved ,anti-freeze, high ... project heating Features: 1) Reliable, efficient, twin-glass solar tubes heat pipe.2) Copper heat pipes for rapid ... Degree7) Tested according to EN12975-2,with Solarkeymark Certificates.8) Guaranteed min. power output of 525kWh/m² (certified by ... commerical large project hot water heating Tubular solar collector with heat pipe