THE FACILITY FOR THE EVALUATION OF THERMAL LOSSES OF HOT WATER STORAGE TANKS

The reliable estimation of the quantity of heat losses, considered as a useful source of information for the manufacturer, constitute the main requisite for the compliance of the hot water storage tanks with the requirements imposed by the EU Regulations 812/13 and 814/13 as stated by the European Directives on Energy Labelling and Eco Design.

In our Laboratory was developed an up to date, fully automated installation, in full compliance with the requirements of the above mentioned Regulations. This facility allows the determination of the heat losses of hot water storage tanks according to the EN 12897 Standard (Determination of the standing heat losses) and the ISO 9459 one (Determination of thermal losses - stand-by heat losses). The heat loss constitutes the basic quantity that determines the energy class of a certain product.

The facility is essentially consisted of two hydraulic circuits for each test position. (a) the water supply circuit , which is directly connected to the main water supply (comprising flow regulating valves, automatic shut-off valves, flow meter, safety valves and thermocouples) and (b) the recirculation circuit , comprising the recirculation pump, automatic shut-off valves and thermocouples).
The facility has the capability to test simultaneously three storage tanks 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), the automation system permits the flowing of water, with the required flow rate and temperature, into the storage tank under test. The water inside the storage tank can be homogenized by recirculation pumps, when required. The flow rate is measured by means of a calibrated flow meter and the temperatures by using calibrated thermometers. The water is heated up to the desired temperature by means of electric resistances.

Following specific scenarios, which are provided in detail by the relevant Standards and Regulations, measurements of temperature and flow rate are performed. The data collected and recorded are therefore processed, identifying the corresponding heat loss figures, characterizing therefore the performance of the storage tanks and classifying them into energy categories.