There is a nice UPS system for 12v bus systems.
as discussed here
https://forumtest.velbus.eu/t/battery-backup/15794/3
Or you can invert an input channel so that on power up, it puts a “pressed” message on the bus, that things react to and set your default state
That’s not something everyone wants.
But you can use thermostat alarm channels to do that for you.
-
Temp is 10ºC above target, swap to cooling mode
-
Temp is 10ºC below target, swap to heating mode
(I have this is my main room, I did try with smaller thresholds, but I noticed it changed operational modes too often. As in going to Night mode would put the cooling on to force the room temp down, instead of allowing it to cool naturally.
The whole house swaps from Winter programming to Summer by an action from the WeatherStation now, but that’s a different subject)
you could…
Set an Alarm to trigger when the target temperature is Below the current target.
This would mean you can have the thermostat in Heating mode and use the pretty icons, but it would actually trigger a cooling system?