1.Solar water heater the copper coil is inside of nonpressure tank,the copper coil could bear the pressure by 0.7mpa during the operation.
2.it is with feeder tank and could load the water automatically.
3.vacuum tube heat the water inside tank,then the hot water in tank could heat the water in the copper coil.
4.it is a pre-heating and heat exchanging process.
5.only if the water in tank is hot,you could get more hot water and it exceeds the limit of the capacity of tank.
6.clean hot water
7.you could use the hot water inside copper coils and also use the hot water in the tank.