THE FACILITY FOR THE EVALUATION OF PERFORMANCE OF ELECTRIC WATER HEATERS

The evaluation of the energy performance of electric water heaters (e W/H), is a requirement of the EU Directives on Energy Labelling and Eco Design and the relative EU Regulations 812/13 and 814/13, which require the measurement of the electric power consumption and the efficiency of energy consuming products, as a condition in order to determine their energy class.

The Laboratory is equipped with an up to date, fully automated facility, suitably configured to carry out all the measurements provided by the Regulations.

The facility is essentially consisted of two hydraulic circuits. (a) The water conditioning circuit, comprising a 5000 lt tank, a plate heat exchanger, circulation pumps and a heat pump for cooling water (in this circuit a quantity of water is cooled down in order to ensure a temperature of water of 10 ^oC inside the tank) and (b) the testing circuit consisted of a circulation pump, electromagnetic shut-off valves, flow regulation valves, safety and bypass valves, a flow meter and thermocouples for each testing position. The facility has the capability to test simultaneously three water heaters and is driven by automatic control and data logging system, connected with the electrical automation and measurement system.

At specific times of the day (according to the schedule), an automatic valve suitably driven from the automation system permits the flow of water, with the required flow rate and temperature, into the water heater under test. Therefore the required by the Standard thermal energy is drawn off from the water heater The flow rate is measured by using a calibrated flowmeter and the temperature through a calibrated thermometer. Finally the hot water drawn-off is diverted to the drain. To be noticed that the electric resistance of the water heater is continuously controlled by the automation system.

Following specific scenarios, which are described in detail in the relevant Regulations and Standards, measurements of temperature and flow rate are performed, the data collected are recorded and then, after processing, the performance characterization parameters of the electric water heater are determined and hence the classification of the heater in energy categories is achieved.