They tend to be easy to program, and because they run on batteries, the clocks do not lose time during power outages. Before you buy a programmable thermostat, chart your weekly habits including wake up and departure times, return home times, and bedtimes, and the temperatures that are comfortable during those times. This will help you decide what type of thermostat will best serve your needs. A programmable thermostat can pay for itself in energy saved within four years. The location of your thermostat can affect its performance and efficiency.
Place thermostats away from direct sunlight, drafts, doorways, skylights, and windows.
Also make sure your thermostat is conveniently located for programming. Some modern heating and cooling systems require special controls. Heat pumps are the most common and usually require special setback thermostats. These thermostats typically use special algorithms to minimize the use of backup electric resistance heat systems. Electric resistance systems, such as electric baseboard heating, also require thermostats capable of directly controlling 120 volt or 240 volt line-voltage circuits.