How to Repair a Home Thermostat

Is your home's heating or cooling system giving you headaches? Does the furnace kick on too often, even though your thermostat is set at 68 degrees? Before you call a furnace repair man or replace your thermostat, there are a few things you can do to see if you can repair your current one.

Before we begin, you should have a basic understanding of how a thermostat works. Most homes feature a wall-mounted thermostat that is powered by a 120-volt circuit. But, before the 120-volts gets to the thermostat, it is first wired to a transformer which reduces the voltage all the way down to anywhere between 12 and 24 volts, depending on your furnace. This is why all of the wires you see attached to your thermostat are very thin. Now, here are some common thermostat problems and how to repair them.

Problem: No heat from the furnace

Solution: There are a few different potential causes for this type of problem. These include a tripped breaker, a loose connection, a dirty thermostat or a bad battery in your digital thermostat. The first thing you will want to do is to check the electrical panel to see if any breakers are off or tripped. If everything looks OK, then check the battery in your thermostat if it is a digital model. Remove the cover from your thermostat and check all of the wire terminals. Make sure that the wires are all connected to their proper terminals and that no wires are loose or broken off. Use a can of compressed air to clean out the thermostat and a soft brush to scrape away any problematic dust. Turn the thermostat to its lowest setting and clean the bimetallic coil. Then, turn the thermostat to its highest setting and clean the coil again. When finished, set the thermostat to your desired temperature.

Problem: Heat doesn't reach the programmed temperature

Solution: This can be a result of the thermostat being installed crooked. It is extremely important that the thermostat be level for it to work properly. Simply use a torpedo level to determine if the thermostat is crooked and set it level again.

Problem: The furnace short-cycles (turns on and off in rapid fashion)

Solution: This is usually caused by either a loose connection or a dirty thermostat. Follow the same thermostat cleaning techniques as described earlier and it should clear up the problem.

These three issues are the most common problems that affect most thermostats, and in many cases, they can be easily repaired. If you do have an older thermostat, however, it is recommended that you install a newer digital model. It will help to keep your home at a more comfortable level and you can even reduce your heating or cooling bills by programming the thermostat.

Need a new thermostat? Compare brands, types and prices with our Thermostats Buyer's Guide.