Statistical approaches to assess the performance of domestic air to water heat pumps

Air-to-water heat pump (AWHP) is a renewable and efficient technology used in sanitary water heating. This study focused on the employment of statistical methods to compare the coefficient of performance (COP) and electrical energies consumed using 1.2 kW, 150 L split type AWHP and 0.9 kW, 150 L integrated type AWHP, with 0.5 kW as auxiliary electric heater. The COPs and the electrical energies consumed were determined from the controlled volumes of hot water drawn from each tank at different use periods. The average month-day COPs of the specific volumes of hot water from either system were above two. The p-values from the one-way ANOVA (analysis of variance) and the Kruskal–Wallis tests of the groups’ COPs were smaller than 0.01 and showed significant differences at 99% confidence level. The study can assist energy service companies and researchers, to test for statistical differences in the performance among different AWHPs.