Sometimes it already smelled like urine, but then it went away again without us refilling anything. But we almost always have the window open in the HAR. A ventilation system is also installed in our house. The HAR is an exhaust room from which air is extracted, like in our bathrooms, the hallway, and the kitchen.
I also can't say how professional the statement from the technician from Tecalor is, or whether it was just an initial assumption on which all further arguments are now based.
At the moment, the costs are holding me back from consulting an expert. They amount to about 3600 net, including metallurgical examination of the copper corrosion.