Heating & Cooling

Battery Replacement in Honeywell Thermostats: All Models Guide

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Honeywell thermostats are some of the best in the business. These thermostat systems are reliable, effective, and widely used. Understanding the ins and outs of your Honeywell thermostat system is essential. One of the most important functions to understand is how to change the batteries in the system, as the thermostat will not function without them.

All Honeywell thermostats that require batteries store them within the control panel. Some models use battery compartments; others require removing the faceplate to access the batteries. Locate the batteries on the panel to replace them. Be sure to replace them carefully, in the correct orientation.

Locating and replacing the batteries in a Honeywell thermostat system can be challenging, but it is an integral part of thermostat maintenance. Without functioning batteries, the system will not work. Let’s examine the process of changing Honeywell thermostat batteries and how to keep the system running well afterward.

How to Change the Batteries In a Honeywell Thermostat

Changing the batteries on a Honeywell thermostat system is quite simple. It only requires knowing how to locate the batteries and access them.

All Honeywell thermostats that have batteries store the batteries in the control panel. Locate the batteries by removing the battery compartment tray or cover or by removing the unit’s faceplate. Carefully extract the batteries, and replace them. Be sure to place the batteries in the correct orientation.

The battery-powered control unit of Honeywell thermostat systems is integral for the operation of the entire system. Without a functioning control unit, the system will not work. This means that replacing the batteries when necessary is vital to keep the system operational.

Thermostat systems of this type will use AA or AAA batteries, depending on the thermostat model. Some units will draw power from the thermostat’s main electrical supply, but those using batteries will use two or three standard batteries. Any batteries of the corresponding size can be used as replacements. 

Honeywell ThermostatBattery TypeNumber of BatteriesBattery Location
1000 SeriesAAA2Under the cover plate
2000 SeriesAAA2Under the cover plate
3000 Series AA2Under the cover plate
4000 Series AA2 Under the cover plate
5000 Series AA2Battery compartment
6000 Series AA2Battery compartment
8000 Series AAA3 Under the cover plate

Always be sure to turn the thermostat system off before replacing the batteries; this will prevent damage to the control panel and the greater system. It is always wise to shut off the mains power to the thermostat system. Exposed wires within the unit may cause an electrical shock.

Some control panel faceplates require removing a small screw located under the faceplate to access the batteries. 

Once locating the batteries in the control panel, carefully remove them from their compartment and replace them with a fresh set. Be sure to always install the new batteries according to the orientation indicated in the compartment, or you may cause damage to the thermostat system.

Once the batteries are correctly installed, carefully secure all parts back into their correct position to ensure normal function.

Changing the batteries will not cause the system to reset any of your pre-determined settings, but it may change the date and time displayed on the unit, which will need to be corrected.

Where are the Batteries In a Honeywell Thermostat?

Honeywell produces many thermostat systems, many of which require batteries for the control panel to operate. 

The batteries on all Honeywell thermostat models are within the control panel of the system. The batteries are either held behind a sliding tray compartment or within the main body of the control panel itself

All Honeywell systems that use batteries will store the batteries somewhere within the country panel unit. Most models require removing the faceplate to access the batteries, but some models have a removable tray or lid that allows the batteries.

To locate the batteries, first, check toward the top right-hand corner of the control unit. If there is no indication of a battery compartment, then the batteries are most likely within the unit.

If you see a marking for a battery compartment, press the tray lightly and slide it open to reveal the batteries.

If there is no battery compartment in the unit, the faceplate will need to be removed from the base to access the batteries. This is a simple process and requires no tools. 

Pull down gently on the control panel faceplate, and it should unclip easily from the base unit. The faceplate can be stubborn to remove, but as long as you’re careful when removing it, the unit should sustain no damage.

This will reveal the batteries, allowing you to replace them with ease.

How Do I Know If My Thermostat Needs a New Battery?

All Honeywell thermostats that use batteries will have an indicator on the control panel. If the system has a screen, a warning such as “Low Batt” indicates that you must replace the batteries soon. Some models do not have an indicator but will instead flash the snowflake icon.

If the Honeywell thermostat system that you have installed has a screen or a control panel, it will most likely require batteries to power that control panel. Every thermostat model like this must have some form of indication for when the batteries are running low.

Fortunately, Honeywell thermostat systems only require a battery change of about once a year. The extended battery life indicates that these systems do not use batteries very quickly. Even when the low battery indicator does come on the screen, you will still have about two months before the control panel stops functioning.

Some Honeywell systems have a final warning feature if the batteries become too low on power. If the batteries get too low, the screen will not turn on until fresh batteries are installed. This is the final indication of low batteries.

How Do You Reset a Low Battery On a Honeywell Thermostat?

The low battery indicator on Honeywell thermostat systems will disappear within a few minutes of installing new batteries. If the indicator does not disappear automatically, the system may require a restart to reset the indicator. Advanced models can be reset by following instructions in the display menu.

It is not uncommon for the low battery indicator to remain active after changing the batteries. The indicator should turn off automatically after about five minutes or so. Still, if it remains any longer than that, the system may need to be restarted at the main circuit breaker or reset internally.

Resetting a Honeywell thermostat that does not have a reset option in the control panel menu means the system will need to be powered down by turning off the circuit breaker. 

The first step in the process is to turn off the thermostat system at the control panel. Next, locate the circuit breaker board, and identify the thermostat power switch. Turn the thermostat circuit breaker to the off position.

Once completing this process, remove the batteries from the thermostat control panel, even if the batteries are fresh. Wait for a minute or two, and replace the batteries. Next, return to the breaker board and turn the power to the thermostat back on.

This should reset all Honeywell thermostat systems and deactivate the low battery indicator.

However, more advanced systems can be reset by following the instructions on the control panel menu or resetting the system from the Honeywell smartphone app if you have a Wi-Fi-equipped thermostat system.

This process is simple. Open the settings menu for the thermostat system and follow the prompts until you find options for “system reset” or “factory reset.” Follow the instructions, and your thermostat system will automatically reset, which will clear any unnecessary system notifications.

How Do I Get My Honeywell Thermostat to Work After Changing the Battery?

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Suppose the thermostat is not working after replacing the batteries. In that case, the batteries are in the wrong orientation, the faceplate may be incorrectly seated, the batteries may be faulty, or the system may require a reset.

The first thing to check if the thermostat system is not turning on after a battery change is if the control panel faceplate or the battery compartment lid or tray has been reinstalled correctly. If the pins in the control panel are not making proper contact with the baseplate, the control panel will not turn on.

Check the control panel to make sure that it is seated securely. If not, carefully remove the panel as not to damage any connections, and replace it securely onto the base plate.

If this does not solve the problem, follow the steps to access the thermostat battery compartment. Inspect the batteries to ensure they are installed in the correct orientation according to the diagram on the thermostat.

If the batteries are not installed with the correct polarity orientation, the thermostat will not function. If the batteries are installed incorrectly, rectifying this should solve the problem.

If the problem persists, place the batteries into another device to check that they are discharging properly.

If all is well with the batteries and the control panel, the system may need to reset. Since the control panel is not working, you must reset the system by turning off the electrical supply at the circuit breaker.

This hard reset will force the system to reboot. Follow the steps in the previous section to perform a thermostat system reboot by turning off the breaker switch.

If this does not solve the problem, it is time to contact a certified Honeywell technician to resolve the issue without causing damage to the thermostat system.

The “Find A Pro” section of the Honeywell website helps find a qualified technician to assist with the problem.

Will a Honeywell Thermostat Work Without Batteries?

Honeywell manufactures a wide variety of thermostat systems. Many of these systems are programable, but some are not. Non-programmable systems do not have control panels, and therefore do not require batteries. Programmable systems do require batteries to function correctly.

The comprehensive range of Honeywell thermostat systems includes those that require batteries to operate and those that do not.

However, thermostat systems that do require batteries cannot operate without them. The control panel for these systems requires batteries for power. Some systems have control panels connected to the main electrical supply, but these are not very common.

Most control panel operated systems require batteries, and if these batties run flat, the control panel will not turn on, rendering the thermostat system uncontrollable.

Fortunately, the systems that require batteries are not very power-hungry, so the batteries will typically last for a long time. On average, the batteries will need to be replaced once a year.

Some systems are designed to function without batteries. The lack of a control panel identifies these systems. Thermostats that have control panels wired into the electrical mains do not require batteries.

Do All Honeywell Thermostats Require Batteries?

Not all Honeywell thermostats use batteries. Several non-programmable Honeywell thermostats do not require batteries to power the control unit. These units are wired into the main electrical power source for the thermostat, as they draw such little power. These units have no screens or other power-using features.

Some non-programmable thermostats made by Honeywell are so simple that they do not require batteries to function. The control units are do not require a power source, as they are essentially just a switch, and if they do need power, they can be wired into the thermostat power source because they require such little power.

Thermostats such as the Honeywell T87N1000 Tradeline Thermostat do not require batteries. This system has a control unit without a screen or even any buttons. It is simply a dial that sets the temperature of the thermostat.

This system and others like it do not require batteries whatsoever. The downside is that these systems are straightforward and do not have many features. Systems like this have limited capabilities and can not be programmed other than raising or lowing the temperature.

Honeywell manufactures a range of these non-programmable systems. A significant advantage to using these systems is that they are straightforward to use; there is not much to go wrong with them; they are reliable, easy to install, and far less expensive than more sophisticated thermostat systems.

Why Is My Honeywell Thermostat On Cool But Not Working?

Honeywell thermostats are some of the best thermostat systems on the market. They are world-renowned for quality and their effectiveness, but they are not immune from problems. A commonly experienced problem is the thermostat not cooling the house or room, even if the thermostat is on cool.

The most common reasons for a thermostat not cooling include:

  • Problems with airflow.
  • Issues with the compressor.
  • Faulty thermostat wiring.
  • Problems with the furnace or heating system.
  • An issue with the thermostat device.

Of these problems, a blank control panel screen is experienced the most by Honeywell users. This problem is usually not difficult to fix.

A blank thermostat device screen is usually due to dead batteries, or the system has encountered a minor fault and requires a reset.

If your thermostat screen is blank, the first step is to check the batteries in the device. Replace the batteries, reinstall the thermostat faceplate, and check if it is now working.

If not, locate the circuit breaker switch for the thermostat system and turn it off for a few seconds. Restore power to the system, and check if it is working. If this does not solve the issue, it may be time to contact a technician to assess and assist with repairs.


Honeywell produces an extensive range of thermostat systems. Many of these systems require batteries to power the thermostat control panel.

If these batteries fail or run flat, the system cannot operate. The entire function of the system relies on a few small batteries. For this reason, it is important to understand how to change the batteries safely and correctly without causing any damage to the system.

Take the time to locate the batteries in the thermostat, and learn how to change them, so it’s a quick and easy process when you need to replace your Honeywell thermostat’s batteries. 

All Honeywell thermostat models that require batteries are simple to use, and replacing the batteries is quick and easy.

If problems arise after changing the batteries, reset the system to rectify most of these issues. 

If any severe problems persist after a reset, consult the Honeywell troubleshooting guide, or contact a professional Honeywell technician for assistance.



Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.