It’s a universal truth that all thermostat batteries need to be changed or charged at some point. But don’t worry — you’ll need a few minutes, new batteries, and one or two standard household tools for most thermostats. Here are the most popular types of thermostats and how to change their batteries.
How to Tell Thermostat Batteries are Low
Nearly all programmable thermostats on the market have a low battery indicator. Although most high-quality batteries last up to five years, it’s a good idea to periodically check the thermostat display for an indicator, such as:
- A flashing light,
- Battery symbol, or
- Text display stating you have a low battery.
Or, you’ll know the batteries are completely dead if you have a blank display screen.
Is There Any Danger If I Don’t Immediately Change the Batteries in My Thermostat?
Generally speaking, no, but it’s not something you’ll want to procrastinate on. If you have a heat wave or cold snap and haven’t changed the batteries, you won’t have any control over the HVAC system until the batteries are replaced.
What Kind of Batteries Does My Thermostat Need?
Check the owner’s manual to verify the correct type of battery and how many. But, most dial, digital, programmable, or switch thermostats use the following:
- Two AA or AAA alkaline batteries;
- One Button-style 3V lithium battery; or
- One 9-volt battery.
If your thermostat is directly connected to your home’s electrical system, it most likely has a backup battery. This battery allows you to enjoy heating and cooling even with no power. Check the owner’s manual for how often to change the backup battery.
When Should I Change My Thermostat Batteries?
Following a general rule, you should change the HVAC thermostat batteries once a year. Many people change the batteries in the fall when they have an HVAC system tune-up before the winter heating season begins. It’s also an excellent time to change the batteries in your home’s carbon monoxide detectors.
I Have to Change Thermostat Batteries A Few Times Per Year — What Does This Mean?
It could be the quality of the batteries — some batteries only last a few months. Or your thermostat could be failing. Older thermostats beginning to fail usually have one or more of these issues:
- The HVAC system doesn’t turn on;
- HVAC system short cycles;
- Thermostat loses programmed settings; or
- The thermostat is unresponsive to setting changes.
Contact your HVAC professional to investigate and troubleshoot the issue. They’ll also provide a solution, including upgrading the thermostat.
My Nest Thermostat Keeps Showing Low Battery — What Should I Do?
For consistently low battery or other power-related messages, check the C wire connection. If your Nest thermostat doesn’t have a C wire, you’ll need to install one. The wire supplies constant power to the thermostat and stops the backup batteries from draining too quickly.
How to Change a Wall Thermostat Battery
To change the batteries on a standard wall thermostat, you’ll need a flashlight, a flat-head screwdriver, and a few minutes.
- Remove the outer housing cover: Some covers need to be pushed up and then pulled off the wall mount.
- Turn the cover over to see where to install new batteries: Slide a small, flat-head screwdriver into the battery openings to dislodge the batteries. Use your fingers to carefully lift each and remove it from the housing.
- Install the new batteries: Check the positive and negative ends inside the housing and install them appropriately.
- Put the thermostat cover back on the wall mount: Note the back posts align with the wall plate and slide the cover into place.
How to Change a Honeywell Thermostat Battery
To change the batteries in a Honeywell Thermostat, you’ll need two standard AAA alkaline batteries and a few minutes.
- Remove the battery compartment: You’ll find the battery compartment on the side for Honeywell thermostats. Push the tab at the top, then pull the side toward you to remove the compartment.
- Remove the old batteries and throw them away: Inside the battery compartment, you should find two AAA batteries. Always replace both batteries.
- Insert the new batteries: Note the direction for positive and negative sides before installing to avoid a snafu.
- Reinstall the battery compartment: Insert the compartment bottom first, push, then snap it into place. The thermostat should turn on again after a few seconds.
How to Change a Nest Thermostat Battery
First, pull the thermostat display from the base attached to the wall. Then, remove the old batteries from the back of the display and replace them with new AAA alkaline batteries. Push the display back into the base until it clicks in place.
The batteries can’t be replaced if you have a Nest Thermostat E or Nest Learning Thermostat. Instead, you’ll charge the thermostat with a USB cable.
The batteries in your HVAC thermostat may be out of sight, but they shouldn’t be out of mind. When changed on an annual schedule, the batteries and your HVAC system will continue to provide comfort to your house year-round.