Mića came in the afternoon to do the final moves after the old tankless heater was unhooked. The three-phase cable which fed it is now split into one for the gas heater in the garage, and two outlets on the terrace. And he took out the old relay he installed to switch off the electric heating when water was heated for the faucets - together they would require something like 40 amperes or worse, we simply didn't have a cable that strong.
Hour later, Silvija with her family and Arpi came - to get the pictures. The old gambit finally seems to work :).