Quck answer
To change the battery in a Honeywell thermostat, follow these steps:
1. Locate the battery compartment on the back of the thermostat.
2. Open the compartment by sliding or lifting the cover.
3. Take out the old battery and dispose of it properly.
4. Insert the new battery, making sure to match the positive and negative terminals correctly.
5. Close the battery compartment securely.
6. Check if the thermostat is functioning properly after installing the new battery.
Changing the battery in a Honeywell thermostat is a simple process that ensures uninterrupted operation of your thermostat.
Honeywell offers various types of thermostats, and not all of them require batteries. If your Honeywell thermostat is not functioning properly or if it is displaying a low battery warning, it is time to replace the batteries. Most Honeywell thermostats use standard AA or AAA batteries. Changing the batteries in the thermostat is necessary when the display turns off or when it indicates low battery.
Does My Honeywell Thermostat Require Batteries?
The thermostats that are most likely to require batteries are the digital or programmable thermostat models with an LED display, but some of these draw power from the HVAC system in the home. Models that do this have a wire connected to the “C” terminal, which provides continuous power to the thermostat unit. If you have a digital or programmable thermostat without a C-wire, it probably needs batteries.
Tip
Many Honeywell thermostat models with C-wire connections also have a battery holder to provide battery power in the event of a power outage. This allows the thermostat to retain program schedule settings if the power goes out.
What Should I Do If the Batteries Are Dead?
If your Honeywell thermostat requires batteries, it will also have a low battery notification function. This warning will appear on the screen as a flashing banner that says “Replace Battery” or “Batt Lo,” indicating the need to change the batteries. If you fail to replace the batteries, eventually the LED screen will go blank, which is the final warning before the thermostat stops working.
In some models, the batteries only serve as a backup when the thermostat is not receiving 24-volt power from the HVAC system. If you do not replace the batteries when they die, you will lose the date and time settings, but the other programmable settings will remain intact.
Opening Nonprogrammable Thermostats for Battery Replacement
For a non-programmable Honeywell thermostat, such as the RTH5100B, look for a latch on the upper-right portion of the thermostat. Press down on the latch and slide out the battery compartment. Release the batteries from the holder by pressing them out through the hole in the back of the compartment.
Align the positive and negative terminals of the two batteries with the diagram inside the compartment to ensure correct polarity. The left battery should be inserted upright, with the plus side up, while the right battery should be inserted downward, with the minus side up. This type of thermostat permanently stores temperature settings, so there is no need to replace the batteries within 30 seconds.
When Should I Replace the Honeywell Thermostat Batteries?
It is recommended to change the thermostat batteries once a year, ideally before the cold-weather season begins. If you will be away from home for a month or longer, it is a good idea to change the thermostat batteries beforehand. This helps ensure proper climate control while you are away, especially during the winter.
If you live in a climate where outdoor winter temperatures drop below freezing, changing the thermostat batteries before leaving town can help prevent frozen pipes, as the indoor air temperature will remain moderate. If the heat is completely off for several below-freezing days, pipes could burst, resulting in expensive repairs and potential property damage.
Indicators of Low Battery Life
Most Honeywell thermostats have a feature that alerts you when the batteries are starting to run low. The thermostat display will show messages like “LOW BATT,” “REPLACE BATT,” “REPL BAT,” or similar wording about a month or two before the batteries completely die. Low or dead batteries are a common issue that affects thermostats. Thankfully, this can be resolved with simple DIY troubleshooting.
If you don’t regularly check the display but notice that it appears dim and difficult to read, it could be a sign of failing batteries. If the thermostat doesn’t retain the daily temperature settings or doesn’t allow you to change the temperature, the batteries may be the culprit. If the display is completely blank, it means the batteries have already died.
Can a Thermostat Function with Dead Batteries?
If a thermostat relies on batteries as its main power source, it will not work if the batteries are dead. The batteries are necessary for the thermostat to remember temperature settings or to activate and deactivate the central heating or air conditioning. Additionally, if the batteries in the thermostat are dead, you won’t be able to adjust the temperature using the thermostat. The batteries also ensure that the thermostat retains its settings even during a power outage.
Replacing Batteries in Honeywell 2000 Series Thermostats
The Honeywell 2000 series includes models TH2110D and TH2210D. These programmable thermostats have an LED screen and push-button controls, and they are suitable for conventional heating systems, air conditioning, and heat pumps. The batteries serve as a backup when the thermostat is connected to 24-VAC power. It is recommended to replace the batteries with fresh ones once a year.
- Switch the system to the OFF position.
- Gently pull the cover plate out to detach it from the sub-base or base plate.
- Flip the cover plate over and remove the two AAA batteries. Replace them with new AAA alkaline batteries.
- Snap the cover plate back onto the base, and switch the system back to the ON position.
Replacing Batteries in Honeywell 4000 Series Thermostats
The Honeywell 4000 series includes models TH4110D and TH4210D, which are programmable thermostats designed for heating/cooling systems with or without a heat pump. If the REPLACE BATT icon is flashing, you have approximately two months to replace the batteries before they die.
- Pull at the bottom of the faceplate to remove the thermostat from the wall plate.
- Turn the faceplate over.
- Remove the two AA batteries and replace them.
- Attach the faceplate back onto the wall plate.
Replacing Batteries in Honeywell 5000 and 6000 Series Thermostats
The 5000 series, also known as the FocusPRO 5000, includes three models: TH5110D, which uses AAA batteries, and TH5320U and TH5220D, both of which use AA batteries. The battery compartment is located on the side of the unit. The 6000 series consists of models TH6110D and TH6320U, both of which use AA batteries.
- To open the battery compartment, press the tab.
- Reveal the batteries by swinging the compartment out from the faceplate.
- Replace the old batteries with new ones.
- Close the battery compartment by swinging it back into the faceplate and pushing it to snap shut.
How to Change the Batteries in Honeywell 8000 Series Thermostats
The Honeywell 8000 series, including the TH8110U, TH8320U, and TH8321U models, is the company’s most versatile thermostat offering. These thermostats can control up to three heating and two cooling systems simultaneously, including dehumidification. Three AAA batteries are optional and only required if the thermostat is not directly wired to AC power.
- Remove the cover plate or faceplate from the wall plate.
- Turn over the cover plate and remove the used batteries. Replace them with new ones.
- Attach the cover plate back onto the wall plate.
