1.Safety in use,central water supply  2.Energy-efficiency,the rate of absorbing air heat meets 450 percent,   cost-saving.                                                                                                                                                       3.Quiet and environmental,clean energy makes no pollution,low noise in operation                                                                                                                                                       4.Heat-exchanger makes no local hot spot,reliable and long working life.                                       5.Central microcomputer controller,machanical and electrical intergration runing automatically.                                                                                                                                                6.Low cost in one-time investment and maintenance ,easy to install ,small occupation.                                                                                                                                            7.Operation around the clock,modular design                                                                                  8.Automatically defrosting.                                                                                                                         9.Optimum in ultra low temperature(nomal movement under 15 degrees celsius below zero)