... hot water heating system 1.CCC,CE,ISO9001 certificate 2.Offer OEM 3.15years warranty 4.20 days delivery solar hot ... the heat to the water tank, and produces hot water 2) Easy to use, also convenient ... tap water, and the outlet hole produces pressure hot water directly 5) Working principle of low ... water in the vacuum tube directly, through the cold hot water convection, changes the solar energy into heat ...