@StanHD You are my absolute hero! Thanks for pointing that out to me! This is what I ended up with, and it does exactly what I want. I'll expand from here, adding both speeds of the ventilation and adding CO2 measurements from the Netatmo modules. Happy! :D Thanks again! 2017-01-27 15_44_09-Domoticz ...

Hi guys, I'm new to the forum and hope you don't mind me asking help for my non-functional blockly. Not entirely true, it does function, but not the way I would expect it to... and what else is new here? :D Here's the blockly: 2017-01-27 14_22_21-Domoticz.png It's all about the central ventilation ...