How does the T9/T10 control temperature in one room if you do not have dampers?

When you adjust the temperature in one room, it will impact the temperature in the rest of your home. For example, if your basement is regularly 4 degrees cooler than your bedroom, it will continue to be slightly cooler as you adjust the temperature to meet your bedroom preferences. If the bedroom and the basement are both selected as priority rooms, the thermostat will average the temperature of those two rooms, and your basement will still be cooler than your bedroom.