The energy balance of the storage tank is drawn a number of times within the course of the efficiency test of SDHW systems. This is achieved by means of highly accurate temperature sensors in the inlet and the outlet of the storage tank.

Doing this more than the entire volume of water of the storage tank is exchanged. This needs a large amount of fresh water.

The new testing laboratory is independent from the water supply mains. Those are emulated by a cold-water-buffer-tank in combination with a process thermostat having an adequate and sufficient cooling power.

This setup provides advantages to carry out the necessary measurements and experimental investigations.

It is possible to adjust the inlet temperature into the storage tank. That way, the cold water inlet temperature will be exactly the same between two tests. This enhances the reproducibility of the tests. Especially regarding the test of the “ability of the solar plus supplementary system to cover the load” mentioned above. This test is sensible to the cold water inlet temperature.

The adjustment of the cold water inlet temperature is possible with a very high accuracy (0.1 K). That is a basic requirement for the testing of heat storages according prEN 12977-3 [2]. Thus it is possible to not only perform the testing of SDHW systems but also of heat storages.

Measuring errors due to a fluctuating water inlet temperature are reduced. The public water main supply is not always at a constant temperature.

The closed circuit can b

e vented. Measuring errors due to air bubbles in the water mains supply are decreased.