How to change Battery of Honeywell Thermostat (Within Minutes!)

After using your thermostat for a couple of years, you notice that it no longer works as well as it used to. When you check it out, you find the LCD keeps on flashing. The only reason the flashes occur is that the thermostat battery is low.

But how do you change the thermostat battery? Well, it depends on your thermostat model/series. Every model has a different way of alerting you to change the batteries.

  • Honeywell 8000 Series: The model includes TH8321U, TH8110U, and TH8320U. They show battery low by flashing the words on the screen.
  • Honeywell 6000 series: It boasts TH6320U, TH6110D, and TH6220D. They show battery low by displaying a REPLACE BATTERY message.
  • Honeywell 5000 series: Includes models such as TH5320U, TH5110D, and TH5220D. They also flash out a REPLACE BATTERY message.
  • Honeywell 4000 series: Includes Th4110D and Th4210D models that also flash the words REPLACE BATTERY.
  • Honeywell 2000 series: It Includes models such as TH2210D, TH1100DH, TH2110V, TH2100DV, TH2110D, and TH2110DH. They all display a battery low message as an alert.
  • If your thermostat shows any of these alerts, then it’s time to change the battery.

Honeywell 2000 Series

The Honeywell series 2000 models boast an LED screen and push-buttons controls. It is ideal for heat pumps, heating and cooling systems. The thermostats come with backup batteries that you should replace after 12 months. Replacing the batteries in models of this series is easy and you can do it yourself. First off.

How to Reset Honeywell Thermostat

  • Switch your thermostat from ON to OFF
  • Take out the cover plate off the wall and disengage it from the wall plate
  • Pull out the two batteries and replace them with new ones
  • Return the cover plate to the wall plate and switch ON the system

Honeywell 4000 Series

Manufacturer’s program the Honeywell 4000 series models. They design them to run cooling or heating systems. This happens either with/without a heat pump. The thermostat gives you an allowance of two months before it goes dead after the alert. After two months you can.

  • Remove the thermostat by pulling it from its faceplate
  • Turn it over and pull out the two AA batteries.
  • Replace them with new ones and return the thermostat to the wall plate

Honeywell 5000 Series

Honeywell 5000 series models use alkaline batteries. The TH5110D uses AAA alkaline batteries. TH5320U and the TH5220D use AA alkaline batteries. The batteries are on the side of the unit. They are removable and all you have to do is

  • Press the tab to open the battery compartment. Pull it out from the faceplate to expose the batteries.
  • Remove the dead batteries and replace them with new ones
  • Return the compartment to the faceplate. Push it to click it shut.

Honeywell 6000 Series

Honeywell 6000 series resembles the 5000 series. The only difference is that all its models boast AA alkaline. They base their battery on the right side of the control unit. Once the flashing REPLACE BATTERY message comes up, you have up to 60 days to replace the battery.

After 60 days, you can depress the tab, remove the battery holder and switch the old batteries with new ones.

Honeywell 8000 Series

The Honeywell 8000 series boasts of the most versatile company offering. The models run at least three cooling and heating systems at a go. It also runs along with a dehumidifier.

The series models boast three AAA alkaline batteries. Yet, they are optional and are useful when you wire the thermostat to the AC power. To change the batteries.

How to Reset Honeywell Thermostat

  • Remove the cover plate and turn it over
  • Remove the old batteries and replace them with new ones
  • Return the cover plate to the wall plate
  • Switch ON your Honeywell thermostat

Besides the batteries, the Honeywell 8000 series appears bigger than the 5000 and 6000 series. It is also beautiful and compliments the shape of its control unit.

Tips for Replacing a Honeywell Thermostat Battery

With the advancement in technology, we rely so much on it even for notifications. Because of so many notifications on items servicing, we ignore some of them.

Because of ignorance, you can one day find yourself in a cold or hothouse. The cases become an emergency. You end up looking for solutions to regulate your room temperatures. But how can you prevent such incidents from happening? Let us discuss what you need to do.

Inspect your thermostat more. With the widespread use of the internet, you can link your thermostat settings to your phone. This will enable you to get all notifications. Besides the online connection, you need to inspect your thermostat. This notifies you to know its battery condition.

Service your thermostat. For proper maintenance and to keep it working throughout the year. Check if your batteries are leaking and if your switches are working well.

When you see the low battery or replace battery notification, don’t ignore it or postpone the issue. Instead, find out your thermostat series and model type. Measure the battery size and buy new ones in case you don’t have spare batteries.

Use new alkaline batteries. Although rechargeable batteries have become popular, they have many disadvantages. Always consider using alkaline batteries as they are cheaper and long-lasting. Once you replace the old ones with new ones, you can last for up to a year before they expire.

Replace your batteries after every 12 months even when they have not depleted. Regardless of whether you have 2 more months on top before they go completely dead. The routine will help in preventing your coolers or heaters from shutting down.

Common Issues Experienced When Replacing a Honeywell Thermostat Battery

While changing your thermostat battery, you might experience some problems. Here are some troubleshooting tips for issues you might come across.

Most complain of their thermostat failure to work after battery replacement. In such situations, ensure that you;

  • Switch OFF your thermostat
  • Open the battery compartment and remove the batteries
  • Return the batteries this time around in a backward manner
  • Leave the thermostat for a few minutes
  • Switch the thermostat back off
  • Remove the batteries again and insert them in the right manner
  • Switch ON your thermostat

That is how you reset your thermostat, and it should work now. If you find difficulties in resetting, grab the thermostat guide and follow all the instructions given.

Steps to Check the Honeywell Thermostat Model Number

The number of times you change your thermostat battery depends on the model. If you don’t know your Honeywell model, here are some steps to check the model number.

Most Honeywell thermostat models have their numbers printed on the front side. But sometimes you can buy a thermostat without the model number print on the front. In such cases, worry less. You can always check the number on the thermostat LED display or check it at the back of its panel.

How to Reset Honeywell Thermostat

In case you have to find out the thermostat model from the back, you can:

  • First off, ensure that you disconnect the electricity from the circuit. It will shield you from live wire exposure and shocks.
  • Second, slide the thermostat starting from the bottom to pull it off from the base plate
  • Turn the thermostat back and write the model number
  • Fix back the thermostat to the base place as it was

If you don’t find the model number at the back of your thermostat, check it out in the manual.

General Precautions and Equipment Needed

It is important to understand how many batteries you need before replacing them. . First off, most Honeywell thermostat batteries boast either AA or AAA alkaline batteries. So, you need to know if your thermostat has AA or AAA alkaline batteries.

Second, ensure that your battery polarity meets its markings in the compartment. Else, your thermostat will end up getting damaged.

In case your thermostat boasts non-sliding compartment batteries, panic less. To uncover the compartment, remove the cover plate from the bottom, twist it if necessary. It will eventually come from the base plate. Yet, ensure that you switch OFF the power supply to avoid getting electrocuted.

If need be, unscrew a small screw at the base of the thermostat before separating it. Take caution not to destroy the clips or pins while uncovering.

Frequently Asked Questions

Q: What are the best Honeywell thermostat batteries to use?

A: The best batteries to use are AA or AAA alkaline ones. If You don’t know which one to use between the two, confirm with the old batteries already installed.

Q: How can I clear the battery low display after replacing the thermostat battery?

A: Once you replace the old batteries with new ones, the sign should disappear. If it doesn’t, power down and then up to reset your thermostat. You can do this from the circuit breaker. Why does my thermostat refuse to work even after the battery change?

Your thermostat battery polarity does not match its markings and compartment. Another reason is that your batteries might get drained. If the two reasons are not the case of your problem, you can contact Honeywell company to sort the issue for you.

Final Thought

If your Honeywell thermostat contains an LED display, it will notify you when its battery is low. If you ignore the text, you get a blank screen after some time and it goes off. To be on the safe side, be keen on the notifications and replace the batteries after every 12 months. Be keen to switch from ON to OFF before changing the batteries to avoid damages.



I spend each darn end of the week taking a shot at home tasks and trimming down the “nectar do” list. This is where I share the majority of the undertakings I’ve done and things I’m learning.

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