The heat exchangers produced from Hennly have a rapid heat transfer and high heat exchange efficiency. They can let the cold (liquid) water calmly heated to the boiling point. Since the using of new muffler structure, the noise is reduced to less than 50dB, and solve the high cost of traditional heating, wide noise, occupied room area, large installation works and other problems. Besides, it can be connected with intelligent water wet automatic controller, liquid level automatically controlled alarming device, automatic operation of the hot water preparation system.