How to Change a Thermostat Battery

When was the last time you changed the batteries in your HVAC thermostat? Did you even know your thermostat uses batteries? If the answer to either question is I don’t know, that’s okay! Here we’ll go over when the batteries are low, how often you should change them, and how to change them in three common thermostats.

How to Tell Thermostat Batteries are Low

Low HVAC thermostat batteries might not seem like a big deal, but they can cause various issues. Plus, if your thermostat relies on batteries for backup power, you won’t have control over the HVAC system during a power outage.

1. The Display Shows a Low Battery Icon

This icon usually appears when the batteries are within one or two months of completely draining. It’s recommended to heed the icon’s appearance since low batteries can affect the thermostat and HVAC system’s functionality, causing one or both to act erratically.

2. The Thermostat Display is Blank

When the batteries completely drain, the thermostat display goes blank without a power supply. Changing the batteries usually resolves this issue. But if new batteries don’t make the display turn on again, you may have an electrical problem, or the thermostat has failed and needs to be replaced.

3. The Thermostat is Programmed, but the Air Isn’t Warm or Cool

When the thermostat doesn’t have an ample power source, such as batteries, it can’t tell the HVAC to produce the set air temperature. This can be a serious issue if there is a heat wave or cold snap, as your home won’t have adequate heating or cooling.

4. The thermostat Isn’t Reading the Room Temperature

Misreading the room temperature can happen when there isn’t enough battery power for the thermostat sensors to operate. If swapping out batteries doesn’t resolve the issue, contact an HVAC technician to investigate further.

Why Are My Thermostat Batteries Draining Quickly?

• Corroded contacts: When batteries leak acid, the acid causes a chemical reaction between the contact and the battery. A layer of flaky discoloration builds up and interferes with the electrical flow, causing the battery to drain more quickly.
• Using the wrong type of battery: Check the user manual for your thermostat and make sure you’re using the correct battery voltage. Most thermostats need batteries with 3.6 voltage, while many consumer batteries are 1.5 voltage.
• Old HVAC thermostat: Although thermostats can last decades, they consume more energy — batteries — as they age and try to keep up with heating and cooling demands.

How Often Should I Change My Thermostat Batteries?

Once a year should be enough to avoid any heating or cooling disruption. Many homeowners are reminded to switch them out at the same time as their spring or fall HVAC tune-up appointment.

How to Change a Wall Thermostat Battery

Available for more than a century, wall thermostats generally have one of three controls: dial, switch, or programmable. Each type uses battery power to communicate with the HVAC system. Since wall thermostats can last for decades, you may need a small, flat-head screwdriver to remove the batteries.

1. Remove the thermostat housing from the wall mount by pulling it toward you or sliding it upward and then pulling it from the mount.
2. On the backside of the housing, you’ll find the battery slots — use the flat-head screwdriver to pry the batteries out gently.
3. Check the connection notations, then slide the new batteries into the slots.
4. Align the wall plate pins with the terminal block and slide the thermostat housing into place.

How to Change a Nest Thermostat Battery

First introduced in 2010, the Nest smart thermostat is still one of the most popular on the market. With voice-activated commands and the ability to control it anywhere from an app, homeowners like this thermostat. And although it’s smart, the Nest still requires batteries.

1. Remove the thermostat display from the wall-mounted base.
2. Inside the display, you’ll find two 1.5V AAA alkaline batteries; remove them and throw them away.
3. Insert two new AAA batteries, ensuring the positive and negative ends align correctly.
4. Push the display back onto the wall-mounted base — you’ll hear a click when it’s in place.

If you have a Nest Thermostat E or Nest Learning Thermostat, these batteries can’t be replaced and need to be charged with a USB cable.

Changing the batteries in your HVAC thermostat is easy and only takes a few minutes to support your home’s heating and cooling year-round.

If you need HVAC service or repairs, contact Service Champions today!