Due to low cost and simplicity of installation, air source heat pumps (ASHPs) are widely used in the world. However, when the ambient temperature is low in winter, the heat output and COP are decreased, and the discharge temperature is increased. The paper is focus on the shortcomings of air source heat pump for residential heating. The capacity of the ASHP decreases sharply when the outdoor temperature deviates badly from that of mild working conditions. As ambient air temperature increases, the COP increases, as does the capacity. As the air temperature drops, frost can form on the evaporator coils, which add heat transfer resistance and blocks airflow. A reverse operation of the heat pump cycle on frequent basis removes the frost but this reduces the capacity and COP of the system. At low ambient temperatures, a heat pump will have inadequate capacity to heat the building, and so a supplemental heat source is required. The results showed, for the rate of frost formation, it depends on the temperature of the air, and the humidity, the evaporation temperature, and the design of coil. Also, we are developing a high performance ASHP using a phase change material (PCM) energy storage and no frost evaporator. The evaporator will be specially-designed evaporator to use a hydrophobic surface, so water does not collect on the surface. The heat pump condenser temperature could be much lower than those used with conventional radiator systems. The hot water temperature could be as low as 30° C.