When are compensators necessary?

Nowadays, plastic is also used for heating. At most, the structure at the boiler, but that won't be 10m long.

Correct! It is not underfloor heating, but classic radiators. And here, supply and return pipes are made of copper. But the pipe lengths are quite long.

Nowadays, plastic is also used for heating.
At most, the structure at the boiler, but that won't be longer than 10m anyway.

Ah okay, I didn't know that. Here, the supply and return pipes are still made of copper. Does that have major drawbacks? Then I would at least have it done differently for the upper floor at some point.

I believe copper is still common. In recent years, composite pipes made of plastic and aluminum have become increasingly popular.

Copper is far too expensive. Aluminium plastic is standard

Unfortunately, I cannot choose because it is stock.