Because programmable thermostats are a relatively new technology, you should learn as much as you can before selecting a unit.

Choosing a Programmable Thermostat

When shopping for a thermostat, bring information with you about your current unit, including the brand and model number.

Also, ask these questions before buying a thermostat:

• Does the unit's clock draw its power from the heating systems's low-voltage electrical control circuit instead of a battery? If so, is the clock disrupted when the furnace cycles on and off? Battery-operated back-up thermostats are preferred by many homeowners.
  
• Is the thermostat compatible with the electrical wiring found in your current unit?
  
• Are you able to install it yourself, or should you hire an electrician or a heating, ventilation, and air conditioning (HVAC) contractor?
  
• How precise is the thermostat?
  
• Are the programming instructions easy to understand and remember? Some thermostats have the instructions printed on the cover or inside the housing box. Otherwise, will you have to consult the instruction booklet every time you want to change the setback times?

Most automatic and programmable thermostats completely replace existing units. These are preferred by many homeowners. However, some devices can be placed over existing thermostats and are mechanically controlled to permit automatic setbacks. These units are usually powered by batteries, which eliminates the need for electrical wiring. 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. The following table shows an example of how to chart your weekly habits.

                        Geiger Heating