The new accumulator tank

This morning one professional from a HPAC firm, my Dad and I squeezed the new 2000 liter, 500 kg accumulator tank indoors (as I'm not too familiar with such terms, I had to check the proper English term from the side of the tank - I previously used the term "water heater", which is not quite accurate). The smaller container is an expansion tank. Plumbing will be installed later, as the HPAC guy(s) is/are busy.