How to Change Thermostat Batteries

Like any appliance or tool that relies on batteries for power, thermostat batteries need to be changed from time to time. Here we go over how you’ll know when the batteries are low, how to change them in common thermostats, and what happens if you let the batteries die.

How to Tell Thermostat Batteries are Low

It’s important to change the thermostat batteries as soon as you notice an

indicator. If you use a programmable thermostat, which many homeowners do, the batteries save the settings in the event of a power outage.

  • A low battery icon appears: Most digital thermostats have either an icon or text appear when the battery is low. Either may flash or be static until the batteries are changed.
  • The temperature is set, but the air doesn’t match: Without adequate power to the relays and wires between the thermostat and HVAC system, the thermostat can’t tell the system if the temperature setting has been changed. This causes a difference in the set temperature and air temperature.
  • The HVAC system works erratically: Because the thermostat is the control center for the entire system, low batteries can cause it to act wonky, such as a fan that doesn’t shut off.


How to Change a Wall Thermostat Battery

No matter if the thermostat is round or rectangular, uses a dial or a slide, if it’s mounted to the wall with a plate, it’s a wall thermostat. The OG for HVAC thermostats, this type has helped homeowners keep a comfortable indoor climate for decades. While the following instructions are written from a general view, it’s recommended to reference the user manual if you have issues changing the batteries.

  1. Slide the display housing upward then toward yourself, or straight toward you.
  2. Turn the housing over and find the existing batteries.
  3. Gently remove the batteries, using a small flathead screwdriver if necessary to pry them from the slots.
  4. Make sure the positive and negative ends of the new batteries align with the appropriate connectors and press them into the slots.
  5. Press the display housing back into place or slide it downward on the wall-mount then press into place.

How to Change a Honeywell Thermostat Battery

A household name for more than 100 years, Honeywell thermostats are known for its range of programmable models and ease-of-use. The following directions are for most Honeywell thermostats; if you find any discrepancy for your thermostat, check the user manual for specific instructions.

  1. Located a push tab on the thermostat’s top right corner.
  2. Press the tab down until you feel the battery compartment loosen.
  3. Slide the compartment toward yourself to remove from the thermostat housing.
  4. Tip the compartment opening toward the bottom of your hand; the existing batteries should fall out.
  5. Install the new batteries, ensuring the ends align with the connectors.
  6. Slide the compartment in bottom first into the thermostat and gently press until it clicks into place.

How to Change a Nest Thermostat Battery

Nest thermostats let homeowners take programmable HVAC settings to the next level. These thermostats save on energy use, learn your schedule and patterns as to heat and cool your home to your specifications. Plus, voice-activated commands and smartphone apps let you change the indoor temperature no matter where you are. It’s no surprise changing the battery is a breeze.

  1. Remove the display housing by gently pulling it toward yourself.
  2. Inside the housing, locate the existing batteries and remove them.
  3. Align the battery ends with the markings in the housing and press into place.
  4. Press the display housing onto the mount; you should hear a faint click when it’s secure.

nest thermostat

But, if you have a Nest E or Nest Learning thermostat, neither model has replaceable batteries and instead use a lithium-ion battery that’s recharged with a USB cord.

What Happens if the Thermostat Batteries Die?

Nobody intends to let the batteries in their HVAC thermostat completely drain. But, here are three common situations that generally happen when they do:

  • Smart thermostats are inoperable with voice commands and the app: Without battery power, the thermostat can’t respond to commands or changes made from the app or the voice assistant.
  • Blank thermostat display: A blank display means you won’t have a temperature reading, be able to adjust the temperature, or turn the system on — or off.
  • The HVAC system won’t work: As mentioned, an inoperable thermostat means the HVAC system won’t work as expected. You could have heat on an unseasonably warm day, or no cooling in the peak of summer.

battery meme

How Many Times Per Year Should I Change the Batteries?

Ideally, twice a year during your HVAC system tune-up appointments. But, most homeowners can get away with it once a year. An easy way to remember to change the thermostat batteries is to switch them out when you change the batteries in your home’s smoke detectors.

Making sure you change the batteries in your HVAC thermostat before they complete drain is the best way to enjoy surprise-free indoor comfort.

But if new thermostat batteries don’t solve your HVAC issues, contact ASI Hastings Heating, Air and Plumbing for professional service today.