A statistical methodology to compare the performance of residential air source heat pump water heaters

Abstract

The study focused on the determination of the statistical comparison of COPs of a 1.2 kW split type and 0.9 kW integrated type, with an auxiliary backup of 0.5 kW. Both tank sizes were 150 L. The COPs and the electrical energies consumed were determined from the controlled volume of hot water drawn off from each tank, at different time of use periods, during the summer and winter seasons. The results depicted that the average month-day COPs of the specific volume of hot water drawn off (50, 100 and 150 L) from the split and integrated type ASHP water heaters, were above 2. In addition, the p-values derived from the one-way ANOVA test and the Kruskal–Wallis tests of the groups’ COPs of the split and integrated type ASHP water heaters, during the winter and summer seasons, were smaller than 0.01 and confirmed significant differences at the 99% confidence level.

Keywords

• coefficient of performance
• p-value
• one-way analysis of variance (one-way anova) test
• kruskal–wallis test
• significant difference
• multiple comparison test