Vacuum phase change of hot water boiler units working principle:
     Vacuum hot water unit overall phase transition to form a large gravity heat pipe, its from the bottom of the heater and the top of the heat exchanger coil of the heat pipe into a high vacuum pumping the right amount of work after the injection of liquid and sealed. Job at the bottom of the liquid heating heater under saturated steam pressure at the top of the heat exchanger coil outside the condensation heat, the heat exchanger coil inside the hot water from the design temperature and served hot users, condensate liquid at the effects of gravity drops back to the bottom of the heater. Liquid job is always in a vacuum evaporation - condensation - evaporation to vapor - liquid phase, phase-change cycle.