Flair is flexible. In general, you will need at least one Puck to operate your system. Beyond that is up to your use scenario.
With Flair your system can be as small as adding a single Puck so you can have a room sensor for your central system. If you have a room that is too hot or too cold, you might install a single Puck and Smart Vent for that room. Many of our users use this flexibility to control the temperature in their nurseries or bedrooms. If every room is a different temperature and you want a consistent temperature throughout your home, you can place a Puck in each room and replace each of your old vents with our Smart Vents.
We try to be flexible to adapt to your life.