New Methodology of Characterization of Seasonal Performance Factor of An Air-To-Water Heat Pump

The threat of the global warming is alarming. The increase in oil prices remains a persistent worry and today’s energy challenges are truly critical. In this context, heat pumps in the residential sector appear to be an interesting solution to reduce energy consumption and emissions of greenhouse gases. The French government has developed, under the leadership of the “Grenelle of the environment”, two successive tax incentives that have increased the number of heat pumps (HP) sold in France for heating and / or production of domestic hot water. European standards used to characterize the air-to-water heat pump performances are based on one test at maximum load operation for an outdoor temperature of 7°C and an outlet temperature of hot water of 35°C. These operating conditions are very different from real life conditions. They can even be quite unrealistic as they exclude start-up and shutdown, defrosting of the outdoor unit, the part load impact, and the weather and water temperature lifts. In this paper, an experimental study is performed on three air-to-water heat pumps. Tests are realized for outdoor temperature varying between -10°C and 14°C and for three water temperature levels. These tests allowed calculating the average heating seasonal performance factor of the HPs. The aim of the experimental study is to select a limited number of testing conditions and to establish a methodology to assess, more realistically the HP performance.