Ambient temperature (Ta) and inlet water temperature (Tin)
Obviously, the values of Ta and Tin vary seasonally, daily, and even hourly, thus, they are assumed to be constant in this study .The effect of these variations can be the focus of future work. According to the EnergyGuide test for electric water heaters, the ambient temperature can vary between 65°F to 70°F. In this work, Ta is assumed to be equal to the average of those two values, 67.5°F (19.72°C). For the inlet cold water temperature of the water supply, the temperature is assumed to be 60 °F (15.56°C) [41].