Incorrectly adjusted heating system - a case for warranty in new construction?

Then answer all the questions first, then maybe you can be helped. Without information, it is all just guessing.

Here, mainly builders of single-family houses are involved who have not installed a pellet heating system. You need a specialist for pellet heating systems, but they will surely refer you to your heating installer. That would also be my first contact, and if he says everything is fine, then you can certainly investigate further here.

@Rudi What is the system doing? What is the return temperature? How is the circulation pump set? The current circulation pumps can operate with different characteristic curves. Constant pressure and proportional pressure. One for radiators, the other for underfloor heating. If the return temperature is not far from the flow temperature, I would try proportional pressure or the auto setting. This way, only the heat demanded by the living spaces is transported, so that the return corresponds approximately to the room temperature. The system becomes slower, but this is not critical for underfloor heating. Depending on the pump, the electronics need about a week to adapt.