... efficiency vacuum tube Solar water heater 1,high heating efficiency 2, easyly installation 3. energy-saves high efficiency vacuum tube Solar water heater Specification:1) Vacuum ... tubes: Φ47 x 1,500mm, Φ58 x 1,800mm, Φ70 x 2,100mm2) Vacuum ... system with advanced science and technology4) The hot water system fitting for families and work units5) The ...