A heat pump water heater works on principle just like an air conditioner or like a refrigerator. Wall Mounted Heat Pumps, Wall Mounted Water Heater, Wall Mounted Hot Water Heater.Highly efficient Micro-Channel heat exchanger with larger heat exchange area, better heat transfer effect and More durable performance.Not touch with water in the water tank, so the heat exchanger has no risk of corrosion, scaling, leakage, etc.The enamel is coated inside the water tank Which is of high corrosion resistance and of Great pressure bearing.