Statistical analysis of split type air source heat pump water heaters

Air source heat pump (ASHP) water heater is an energy efficient device implemented for sanitary hot water production. Mathematical models were developed and built in respect to SIRAC and Kwikot split type ASHP water heaters that correlate the predictors (difference between hot water set point temperature and ambient temperature (Ts-Ta) and relative humidity (RH)) to the COP. The models depicted that the rate of change of the COP of the SIRAC and Kwikot systems with respect to the RH was -0.0006/% and 0.0189/%, respectively. Also, the rate of change in the COP of the SIRAC and Kwikot systems in relation to (Ts-Ta) was -0.0897/°C and -0.1231/°C. The models were simple and could be used to predict the COP of both systems with over 95% confidence level. Furthermore, based on the predicted COP from the mathematical models, on both systems, a significant difference was observed among the COP means of the two ASHP water heaters with respect to all the hot water drawn off scenarios. The result revealed that the SIRAC performed better relative to the Kwikot type based on the one-way ANOVA test. The p-value obtained from ANOVA was 0.0180 which indicates that there is a significant difference between the COPs of both systems.