To research the principle of air-source heat pump water unit with energy storage and the application feasibility in this field,the prototype of the hot water unit is developed.Performance of the unit in every mode is studied by experiments.Test results show that the unit can efficiently work in multiple modes,such as heat storage mode,heat and cooling storage mode,hot water supply mode,hot water and chilled water supply mode.Especially,the unit works with higher average energy efficiency ratio in heat and cooling storage mode as well as hot water and chilled water supply mode.In energy storage process,water temperature distribution in hot/chilled water tanks is comparatively uniform,which is favorable for improving the capacity of thermal storage.At the mean time,increasing accumulator volume and debasing location of compressor startup can improve the energy-saving potential and enhance reliability of the unit.