Great news !
I've tested the DaikinHeatpumpIR library and I can report that it works with my Daikin Heatpump, type RXS25G2V1B
the remote is ARC452A1
I'm really happy that it works and would like to say thank you to the dev's !
Finally I will be able to start some real energy saving by controlling the Daikin heatpump based on conditions like presence, outside temp, (google)-calendar, and heath generated from a second central heating system (allowing me to choose most economic heathing source).
I already have a Nano based sensor node (near the Daikin unit) for PIR motion detection and DHT22 temp/humidity, so hopefully I can manage to integrate the simple ON/OFF via IR into the same sketch.
If not, another dedicated node will be needed.
@ ToniA, do you expect problems when integrating this into the same Mysensors sketch as PIR + DHT22 ?