From which manufacturer should you buy the heat pump - ventilation system combination?

It must be said fairly, however, that neither a WP nor a KWL require serious maintenance. Nothing that you can't do yourself in 5 minutes and for 5€.

I was probably not precise enough. Besides maintenance, there is convenient support – if anything in the area of heating and ventilation is wrong, there is exactly one contact person. Keep it simple.

In times of skilled labor shortages, there are also companies that then refer to the manufacturer. In that case, it may again be useful to choose a manufacturer because you save on travel costs. But of course, you don't know that in advance; no one advertises that they do not want to provide service..