A room thermostat should be placed in a room to maximize air flow across the thermostat. High air flow allows the air temperature across thermostat to be more representative of the room temperature.

Following figure shows the locations where thermostat should be fitted. Ideal height above floor is 1.2m.  

Dont install thermostat in following 7 areas: 

1. directly in front of heat or cooling source
2. In a different room other than the target room
3. in a direct sunlight
4. directly above appliances like TV
5. in a corner of two walls
6. behind furniture and curtains
7. close to entrance door where temperature is affected by high air infiltration.