Installing a Programmable Thermostat

January 26th 2010
Installing a Programmable Thermostat

One of the least expensive ways to lower your home heating bill is to install a programmable thermostat. Priced between $30 and $100, they are inexpensive, and you can save three to four per cent on your heating costs by turning your thermostat down 3 C for at least eight hours every day.

When purchasing a digital thermostat, buy one that is user friendly and make sure you buy the right model for your heating system. Programmable thermostats will work with most gas or oil furnaces, and central air conditioners. However, heat pumps, electric baseboards, and a few other systems require a special model. Read the package to make sure the programmable thermostat you buy is compatible with your heating and cooling system.

- Install your programmable thermostat unit on an interior wall, away from heating or cooling vents and other sources of heat or drafts (doorways, windows, skylights or direct sunlight.)
- If the job involves more than just a replacement or relocating, call a certified HVAC professional to ensure proper installation.
- It's a good idea to upgrade an old manual thermostat to a programmable unit if you're replacing a heating system given that digital thermostats are far more accurate and will maximize the efficiency of your new system. Have your HVAC contractor advise you on selecting the thermostat for your system.
- If you're replacing a manual thermostat that has a mercury switch, be careful not to break the tube that holds this toxic substance. Contact your local recycling/hazardous materials center, or the manufacturer of your new thermostat, for information on proper disposal.


Read the instructions with the new unit BEFORE starting the installation. Manufacturer's installation instructions might differ slightly for each model. Programmable thermostats are a low voltage wiring installation and involve anywhere from 2 - 10 wires, depending on your type of heating system. However, you should shut down your electricity during any replacement.

Here are the basic steps:

  • -  Turn off the power supply to the thermostat.
    -  Remove the old thermostat, including the wall plate. Older thermostats with glass tubes contain mercury. Use caution when handling and check with your local recycling company for disposal instructions.
  • -  Your thermostat will have two or four wires depending on whether your heating and cooling systems are separate or one unit. Label the wires, noting where they were attached on the old thermostat. Consider using a digital camera to take a photo of the wire placement. Secure them (tie into a loop or tape them to the wall) to keep them from falling back into the wall.
  • -  Install the new wall plate, if there is one. You may need to drill new holes for the new model. Use a level to mark where the holes are to be drilled. Use drywall anchors, if necessary.
  • -  Connect the wires as directed by the instructions that come with your particular unit. Follow these instructions carefully. Install batteries, if needed.
    -  Mount the unit to the wallplate.
    -  Restore power and program the new thermostat as directed.

Programming your thermostat:

If you adjust your programmable thermostat during the day and at night, you will see additional savings. Pre-program your settings for the day, evening and when you are sleeping. Remember, you can set your thermostat's temperature differently for the days you are at home (like weekends). You can also choose times that fit your schedule to adjust the temperature by a few degrees.

Settings/Description Time Temperature Setting:

  • Wake (when you wake up) 6:00 a.m. 21 C
  • Day (while you're away from home) 8:00 a.m. 18 C or less
  • Evening (when you arrive back at home) 6:00 p.m. 21 C
  • Sleep (while you sleep) 10:00 p.m. 18 C or less

For more information on choosing and installing programmable thermostats check out