... roof, balcony or at ground level 6) Free maintenance 7) Suitable for pressure water (8 bars / 116PSI) 8) Corrosion resistant ... CE,UL,ISO9001,CCC,Solar water heater with SOLAR KEY MARK certificate2.High efficiency, Absorption rate: =93%, thermal ... parts are made by our factory. With the same quality of products, we are cheaper than others4 ... always be free. solar water heater/high quality system with CE