Product review (5 stars): Terrific Product for the Price
I now have four of these in different rooms of my house.  Then I regulate the central thermostat to the desired temperature range for the room where the thermostat is located.  I then manually adjust the registers in each room to reduce or increase the air flow so that the desired temperature for that room is obtained.  These monitors are also great for monitoring humidity levels.  I can adjust the water flow into my central humidifier (attached to the furnace) in the winter to keep adequate moisture (about 40% humidity in my case) in the air.  In the summer, I set my two dehumidifiers (one for each level in my house) at the desired humidity (50% in my case).

I also put one in my mother's room at her assisted living facility.  This helped me to alert the caregivers and building operations manager when the temperature became too hot or too cold.  I also was able to alert the ops manager last week when the humidity level had fallen too low (27%).  He has notified his corporate contact and they are now working on getting a humidifier for the furnace.