Ultrasun UVT VacTube Vacuum Tube solar hot water systems are the most efficient water heating systems available. Solar energy is captured in the vacuum sealed glass void heating the water in the glass tube. The heated water rises to the top of the pipe and collects in the tank. The large surface area of the vacuum tube and high water turbulence within the internal chamber provide rapid transfer of heat to the water flowing through the tank. The sealed evacuated tubes and tri-oxide coating provide maximum solar gain even in the coldest areas and during cloudy or overcast days. System features include;