My bad...
I sorted the issue with IR LED not sending. I used an old sketch where IRSender was used instead of IRSenderPWM (probably in combination of updated libraries?)

Hope to get some hints to finalize my IR remote. To start with, I'm fairly new on arduino and I've built some sensors based on mysensors and I have a Domoticz controller running on raspberry pi. I'm using the HeatPumpIR library and the lua script from Toni. The code running on the arduino has been ...