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How to Change the Batteries in a Thermostat


Thermostats are an essential component of any home’s heating, ventilation and air conditioning (HVAC) system. They allow you to set and maintain a comfortable temperature in your home, and they can also help you save energy by automatically adjusting the temperature when you’re away or asleep.

While it’s not always the case, most thermostats do have batteries. Even smart thermostats have batteries, and thermostat models that are wired into your home’s electrical system often have a backup battery to retain their settings in the event your power goes out.

As with any electronic device, it is important to change thermostat batteries regularly to ensure that your thermostat is working correctly. Here, we’ll answer common thermostat questions, explain how to replace a thermostat battery—including how to change the battery in a Honeywell thermostat, which is a brand many homes use—and how to tell when your thermostat’s batteries are low.

How to Tell if Thermostat Batteries Are Low

If you own a digital thermostat with a display, you should see an indicator warning a month or two before batteries die. Sometimes, a thermostat screen will go blank when the batteries are dying. Your heating and cooling systems also might not function if your thermostat’s batteries die completely, which is why it’s always good to check your batteries if your HVAC suddenly stops working.

What Kind of Batteries Does a Thermostat Use?

The most common types of batteries thermostats use are AA or AAA alkaline batteries or 3V disc-style lithium batteries. These batteries help to retain thermostat programming and stop the HVAC system from simple powering in the event of a power outage. The best way to know what batteries your thermostat uses is to look inside the thermostat or reference the instruction manual.

Will Low Batteries Affect a Thermostat?

One of the main reasons to change the batteries in your thermostat is to prevent it from malfunctioning. If the batteries in your thermostat are low or dead, the thermostat may not be able to accurately sense the temperature in your home. This can lead to your HVAC system running unnecessarily, which wastes energy and increases your energy bills. A malfunctioning thermostat may not be able to turn off your HVAC system when the desired temperature is reached, leading to unnecessary heating or cooling.

How to Change the Batteries in a Honeywell Thermostat

Changing the batteries in a thermostat is a pretty simple task, though the process may vary slightly depending on the brand. One of the quality brands many people trust in their homes is Honeywell, and changing batteries in a Honeywell thermostat is very easy.

Here is how to change the batteries in a Honeywell thermostat, though it’s important to note the process is very similar for many other thermostat brands:

  • Turn off the thermostat: Start by ensuring your thermostat is off to avoid any electrical issues during the process.
  • Remove the cover: Carefully remove the cover of your thermostat. Some models may have a latch or screws that need to be undone.
  • Locate the batteries: Once the cover is removed, locate the battery compartment. This is usually at the back of the unit.
  • Remove the old batteries: Carefully remove the old batteries. Ensure to remember the orientation of the batteries as it’s crucial for the replacement.
  • Insert new batteries: Place the new batteries in the same orientation as the old ones were placed. Most thermostats use AA or AAA batteries, but check your unit’s instruction manual if you’re not sure.
  • Reattach the cover: Once the batteries are securely in place, reattach the cover to complete the Honeywell thermostat battery’s replacement.
  • Double-check: Turn your thermostat back on and ensure it’s working correctly. If it’s still not functioning, check the battery orientation or try another set of batteries.

How Often Should You Replace Thermostat Batteries?

The answer to this question depends on the type of thermostat you have and the type of batteries you are using. Some thermostats use long-lasting lithium batteries that function for several years, while others use alkaline batteries that need to be replaced more frequently. It is a good idea to check the manufacturer’s recommendations for your specific thermostat and follow their guidelines when it comes to how often to replace the battery. In general, it is a good idea to change the batteries in your thermostat at least once a year, or whenever you notice that the display is dimming, or the thermostat is not functioning properly.

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