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Electric heating water boilers are gradually replacing the tradition coal-fired boilers, which are widely used in daily life, because of some advantages, such as: convenient, fast, little standing place, automatic control, etc.. Although electric heating water boilers are continuous improvement, this can’t be good to meet our country’s“energy-saving and emission reduction”policy. Therefore, it’s necessary to study a new energy-saving water boiler. Air source heat pump water heater (ASHPWH) is such a energy-saving equipment that it can transfer a large number of free air energy into heat energy to users, only a small amount of power is consumed. However, affect on some factors, such as: thermal efficiency (COP), compressor reliability, unit stability, etc., the conventional heat pump hot water technology to make higher temperature than 55℃exists a certain difficulty. Therefore, at present, we can’t directly make drinking water with heat pump.According to the above mentioned, this paper introduces the energy-saving technology of ASHPWH into electric heating water boilers, with the advanced technology of“step water-supply and serial layer heating”, a new type energy-saving water boiler was presented. Adopt the mode of“two-stage heating”, first of all, water was preheated from room temperature (around 15℃) to around 55℃with heat pump, then around 55℃hot water was heated to the temperature that meet the required of drinking. The main research works and conclusions as follows:1. Frist, design the overall frame of product, then determine the process of heat pump and components, designed the heat pump by calculation and selection, which accorded with water boilers.2. In order to slove the problem of temperature stability from heat pump tank to electric heating water tank, and consider the impact of ambient temperature on heat pump units. Designed two heating control modes:“automatic mode”and“emergency mode”.“automatic mode”to ensure that the supply water temperature from heat pump tank to electric heating water tank has better stability, so as to significantly enhance the energy-saving effect of this product;“emergency mode”to ensure that the product still can provide drinking water to users when the ambient temperature is lower against heat pump operation or heat pump units malfunction fail to run.“Smart mode”and“full mode”, two management modes were also designed, which facilitated water boilers applied in different places.3. According to the design scheme of product, prototype was manufactured.4. The related performance of product were tested, and map the curves of the impact of ambient temperature、hot water temperature on input power、heating capacity、EER, low-temperature part energy efficiency of this water boiler was analyzed, and its energy-saving effect was also reflected.
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