The inside of vacuum tubes does not circulate the water. The absorbent layer transforms solar radiation into thermal energy and the heat pipes transmit it in a heat exchanger (heating element of water) located in the tank. a solar termica Espana. termosifon solar Madrid
This system is perfect for less insolated regions: areas with a lower annual rate of sunny days, of low ambient temperatures and also for “hard” (highly mineralized) water. The heating element is a 1,80 m long vacuum tube with an internal “heat pipe” – a smaller copper tube filled with a special liquid. The internal “heat pipe” (i.e. thermotube) collects and transfers the heat up to the copper head located inside the water tank. The copper head, in turn, heats water in the tank. The tank is always hermetic, and the system works well even with one or more vacuum tubes removed. This type of water heater can be easily integrated with any existing gas or electric water heating (or house heating) system.