... EN12975 solar keymark 2.Anti-freezen & pressurized 3.10 years warranty Water heater systemWorking principle:when the diffeference of collector ... pipe: anti-freezing > -35 degrees centigrade9) Water capacity: 150L, 200L, 250L, 300L, 500L 10) Pressure: 6 Bars11) Daily efficiency: >= ... selective absorption coating,Vacuum Degree,P<=5*10-4,Service Life,10 years Mounting FrameAluminum Alloy,Thickness,1.8 mm, ...