The device will work in sync with the main system both in Eco and auto mode. Meaning, the fans only spin when the main system is on heating or cooling.
Eco: The fans only spin when the main HVAC system is working on heating or cooling, which makes it the most energy-efficient state.
Auto: In Addition to working in sync with the main HVAC system on heating or cooling, after the learning period is finished, the user can see and adjust the temperature for each individual room. So the device will stop working when the room gets to the desired temperature even if the main system is still running.