Fixing a Broken Thermostat: Why Isn't My Thermostat Working?

When your furnace isn’t working properly (or at all), the problem isn’t always the furnace. It could be the thermostat. If the problem is with the thermostat, you’re lucky - that’s usually a much cheaper fix than the furnace.

Once you’ve confirmed that the furnace is not the problem, there are some things you can do to troubleshoot on your own before calling a repairman. If those don’t work, then it’s time to hire a handyman or HVAC professional to repair or replace the device.

Troubleshooting

A broken thermostat can cause extreme temperature swings, a furnace that cycles on and off too frequently or a furnace that does not produce heat. To find out if the thermostat is the problem, turn it to the opposite setting (if you’re using the heat, turn the thermostat all the way to cool) or just turn the temperature way up. If nothing happens after a few minutes, the thermostat is broken or faulty.

There are many reasons why a thermostat stops working, including some that are very simple to correct. Go through this list before calling in a professional:

• Check to see if the circuit breaker has been tripped or a fuse is blown. If so, reset the circuit breaker or replace the fuse.
• Check for loose wires and/or loose screws. Tighten them if needed.
• Try replacing the battery (digital thermostats only). If your thermostat is wireless, make sure you’re using AA Lithium batteries. Regular alkaline batteries won’t last long in a wireless thermostat.
• Remove the thermostat cover and (carefully!) clean the components with a small paintbrush. Sometimes a thermostat won’t work simply because it’s dusty.
• Remove the cover and see if you can feel any particularly cold or warm air coming from the wall. If so, add some insulation around the thermostat or caulk around it.
• Make sure the thermostat is on straight (not crooked) and located in a part of the house where it can accurately measure the air temperature (usually an inside hallway or an area like that living room you use often, and preferably near a return air duct; never in drafty areas or near a heat source).
• Adjust the heat anticipator

Replace or Repair?

If your troubleshooting is not successful, now it’s time to decide what’s more economical: repairing the thermostat or replacing it. Your repairman or HVAC professional will be able to provide advice on what’s best, but it’s generally a good idea to replace if your thermostat constantly breaks or if the repair is more expensive than a new thermostat. If you’re buying a new one, always consult a professional first. Not every thermostat is compatible with every type of furnace.

Repair and Replacement Costs

Manual or basic digital thermostats start at about $20, and wireless digital thermostats start at about $100. Wireless thermostats with features like web integration and touch screens can cost $200 to $500. Installation costs vary based on the type of thermostat, the time required and your geographic location, but in most areas you won’t pay more than $100 or $150.

Repair costs depend on the nature of the repair, as well the time required and your geographic location. Most repairs cost anywhere from about $50 to $250. Always get a quote for both repair and replacement before having any work done to find out which makes better financial sense. Don’t pay more for the repair than you spent for the thermostat. Most professionals won’t steer you wrong, but it’s best to be sure.

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