Hi Pascal. I just stumbled on your post, I just wanted to respond.
Maybe I misunderstand, but this is pretty straightforward to build.
IF a contact alarm changed to state off
AND window1 contact is off
AND window2 contact is off
THEN switch heater ON
ELSE switch heater OFF
And, if window1 is opened, and window2 is closed or open or the other way round;
IF a contact alarm changed to state on
AND window1 contact is on
OR window2 contact is on
OR window1 contact is on
AND window2 contact is on
THEN switch heater OFF
+1 and I would like to add: some overview of which var is used in which flow(s).
I also want you and @lucje point to a neat flow editor app, which let you build flows way more flexible H.O.O.P. (Hope) - Homey Object Oriented Programming
