Discharge Performance of Domestic Water Heater

Water is generally heated in domestic buildings using an immersion-type electric water heater (EWH) which includes a thermostat installed at the bottom of the tank. Although these systems are powered by electricity, which is more costly than solar water heating, they are nonetheless extensively utilized because of their convenience and low installation costs. The thermostat position and water set-point temperature are critical for efficient and economic usage of electric water heaters. Accordingly, the impact of locating the thermostat at three different altitudes, namely near the bottom, middle, and top of an EWH, is investigated in this work. In addition, the effect of thermostat set temperature at the bottom of the tank on the EWH's performance is tested experimentally. During the experiments, the heated water was discharged at a rate of 5 L/min, and data was collected. The discharge efficiencies for the thermostat position at the bottom are found to be higher, whereas the discharge efficiencies for the thermostat positions in the center and towards the top are quite similar but lower than the one near the bottom. Water heating for home usage with solar energy is also a well-known and practical technology that is widely used. Most available systems, on the other hand, have the solar collector and the hot water storage tank as distinct components, requiring plumbing and additional thermal insulation for both. Combining the solar collector and the hot water storage tank into one unit eliminates extra insulation, piping, and hot spots, and also it requires less space to install the system in buildings. Also, the integrated solar collector water heaters can be used in colder climates without antifreeze solution since there is no risk of freezing like in the pipes of flat plate solar collectors. Accordingly, a novel trapezoidal-shaped integrated solar water heater is developed and tested in this part of the study. In comparison to the previous design, the new one allows the end-user to install and use it in a smaller area while maintaining the same efficiency and cost savings compared to the conventional design. The temperature profile inside the new storage tank is measured with 33 thermocouples for two different volumetric flow rates, 5 L/min, and 10 L/min, and compared to the temperature profile inside the old storage tank. Based on the results, the highest solar intensity and water temperature during the experiments were 890 W/m2 and 54.6 °C, respectively.