Preparation for possible air conditioning of the attic

In my opinion, the drainage of the condensate is one of the biggest challenges, especially during retrofitting. It is not exactly trivial to install a pipe with a continuous slope from the indoor unit to the nearest drain pipe in an existing building.

We didn’t prepare but installed everything directly, however as a tip: the condensate drain is really the "biggest" problem! Be sure to provide drain pipes in the appropriate places. There we then have these "automatically closing adapters" where the hose is attached. Never permanently fix the condensate drain hose anywhere (e.g. screed) as they could get clogged. We put all of them in the ceilings and would still be able to reach them in case of emergency. The slope is also important. You can hear the pumps and especially in the bedroom you don’t want that. The device itself is significantly quieter..

Do modern devices not even evaporate the condensate for greater efficiency, or is that a misunderstanding?

Thank you very much for your experiences/suggestions and tips! One more question about the power supply: Does such a split unit require a three-phase power connection or is 16A alternating current sufficient?

Not the usual and modern split systems no matter what the indoor unit may look like