|until the lime has eroded the thermoblock in places like connections etc.|
That may be well. But with normal machines (what I wrote about were filter machines) there aren't really any instructions for decalcifying, are there? I have to admit, I never looked at the instructions.
If the pipes are built properly, however, lime does not cause any problems. I know about my pipes, which are installed in the house, there is still nothing broken after fifty years. ;-) And when a piece had to be sawn out for a branch, the pipe looked like new from the inside under the lime layer, which was very thin, against my and the installer's expectations of the water hardness on site (> 20).
But well, that's another topic.