How to quickly replace / change batteries in a Honeywell thermostat – it’s easier than you think!

Written by David Lewis
7 Min read

Most of us will confess to not having a clue when it comes to DIY and will call in the experts as soon as something breaks or stops working in our homes – leaking taps, faulty ovens, and blocked drains all have us reaching for Google to find a tradesman nearby who can get us back on track again, ASAP.

But one job that can be tackled quickly and easily by even the most reluctant DIYer is replacing a thermostat battery.

Read our helpful guide to find out how, or make use of our friend’s video guide here.

Honeywell Pro Series Thermostat Battery Replacement (BATT)
Video guide on changing the Honeywell thermostat batteries

How do you replace the thermostat battery? – A step by step guide

When did you last check your thermostat?  Chances are this hasn’t happened for a while (if ever!) and so this is your friendly reminder that now is a great time to check on one of the most useful gadgets in your home.

Things you will need

  • A small, flat-blade screwdriver
  • CR2032 3V lithium battery, or AA/AAA alkaline batteries

How to take the cover off a Honeywell thermostat

Whether round, square, or rectangular, most Honeywell thermostat covers are removed in the same way and are pretty easy to take off. However, if you pull it off incorrectly you could break it by cracking the cover or snapping the clips off.

Some Honeywell thermostats feature a slide-off battery compartment, in which case you won’t need to remove a cover to access this.

Firstly, you should ensure the power is off before attempting to remove the cover, especially if you’re going to be going anywhere near the wiring.

The covers on most Honeywell thermostats can simply be pulled off, but before you apply brute force check around to see whether there are any clips securing it in place, if so you will need to gently push these before pulling the cover off.

Releasing the batteries

In order to release the thermostat battery, pry it out using a small, flat-blade screwdriver to lift it out of the battery housing unit.

Putting the cover back on

Once the thermostat battery has been replaced (making sure you placed the batteries in the right direction) you should now push the cover back in place, using the opposite motion to how you removed it.

Then you simply turn the power back on and test the thermostat to ensure it’s working correctly.

Resetting after changing the thermostat battery

If you’re able to change the thermostat battery when it is displaying a low battery warning, you shouldn’t need to completely reset any pre-programmed timings. However, if your thermostat batteries have died, or you need to perform a factory reset for any reason, you may need to reprogramme your pre-set temperature timings.

About Honeywell thermostats

Man adjusting thermostat and changing thermostat battery

Honeywell is an American company responsible for the invention of the automatic heating system in 1885.  Since then, they’ve made it their mission to ‘transform the way the world works’ and have been leading the home heating industry ever since. With up to a quarter of all the homes having a Honeywell thermostat installed, you’ve probably grown up or lived in a Honeywell temperature-controlled home for many years.

Different types of thermostats

There are four different basic types of thermostats available:

  1. Non-programmable
  2. Programmable
  3. Wi-Fi
  4. Smart

Non-programmable thermostat

A non-programmable thermostat is the most basic thermostat available and is perfect for people who are rarely away from their homes.

The temperature is changed by manually rotating the temperature dial up or down, according to your heat needs.  As the name suggests, it cannot be programmed to turn off or on at specific times and the temperature will remain consistent unless manually adjusted.

Programmable thermostat

Programmable thermostats allow you to pre-program temperatures for specific periods of time during the day or at night. They provide good control by allowing the user to predict required temperatures and adjust the temperature accordingly ahead of time, without any extra manual intervention.

Programmable thermostats usually feature daily and weekly settings, which means you can vary the temperatures both during the week and at weekends, when you’re likely to be in the house a lot more but are powered by a thermostat battery.

Wi-Fi thermostats

Wi-Fi thermostats are essentially programmable thermostats with extra zhuzh! Featuring all the same controllable elements of a programmable thermostat, you can also connect to them via a wireless network and remotely adjust the temperature settings from your smartphone, tablet, or laptop.

This type of thermostat is perfect for anyone who wants the reliability of a programmable thermostat but with the added flexibility of remote access.

Smart thermostats

Smart thermostats offer the ultimate in indoor temperature control. They can help to save you money on your energy costs by learning about your living habits and making micro-adjustments to the temperature accordingly.

They work by connecting to the internet, giving you the same control as a Wi-Fi thermostat. Other features include multi-room control, hot water control, geofencing to track when you go in and out of your home, draft detection, and holiday mode.

It’s probably worth noting that smart thermostats are different from smart meters which are provided by energy companies and monitor your energy usage as opposed to allowing you to control it.

How do I know if my thermostat battery needs changing?

With most modern programmable, Wi-Fi enabled, or smart thermostats the most obvious way to know that the thermostat battery needs changing is because it will tell you! When the batteries are nearly depleted, a low battery indicator will appear on the digital display of your thermostat. In some older models, a light may be displayed rather than an on-screen message.

Digital thermostats give you a month or so notice that the batteries need replacing, which should give you plenty of time to shop for a new thermostat battery.

What happens if your thermostat battery dies?

If the display on your thermostat has gone completely blank, this is a good indication that the batteries have died. If this happens, you will most likely have lost any pre-programmed settings, and you will need to remember to reset these as soon as the thermostat battery has been replaced.

How to factory reset your Honeywell thermostat

Each different Honeywell model will have a slightly different factory reset method, however, as a general rule most thermostats will be reset to factory settings by taking the following action:

  • Switch off the power and remove the thermostat battery
  • Replace the thermostat battery but in reverse polarity
  • After 10-15 seconds, remove the thermostat battery and replace it the right way round

In conclusion

So, there you have it! As promised, this is one of the easier home maintenance jobs, but if you manage to get your thermostat working again without needing to call in a professional you can still feel very proud of yourself.

However, this guide comes with a word of warning – don’t skimp on the batteries and use old ones. These could be corroded and leak into your thermostat, which definitely won’t be as simple to rectify.


Can low batteries affect your thermostat?

Getting a low battery warning on your digital thermostat display shouldn’t affect its function. However, if the battery power is so low it doesn’t have enough power to operate the thermostat you may notice some strange behavior. For example, your system may not turn on, turn on and off repeatedly, or it might make strange noises.

Do all Honeywell thermostats have batteries?

No, not all Honeywell thermostats run on batteries, but if your model features an LED display there is a high likelihood that it does.  Some models use AA alkaline batteries, whilst others require AAA batteries.

What kind of battery does a Honeywell thermostat take?

The vast majority of Honeywell thermostats run on a combination of AC power, AA or AAA batteries. If you want to establish what type of battery your thermostat needs, you will need to check the model type.  The model number can be located on the side or back of the thermostat, you will need to remove the faceplate in order to find this.

Why is my Honeywell thermostat not working?

Your Honeywell thermostat may have stopped working because of one of the following issues:

·       It has no power – check for power cuts
·       The wiring is loose or corroded – always switch off the power via the circuit breaker before going near loose wires
·       The thermostat needs cleaning – use a dry, clean, soft toothbrush to dust the inner workings of the thermostat
·       It isn’t level on the wall – thermostats feature a mercury bulb that must be level to operate
·       It has been installed in the wrong place – thermostats should be positioned in a central area of your home, away from windows, doors, and air registers

What type of battery does my Honeywell thermostat use?

Most Honeywell thermostats use either AA or AAA alkaline batteries, or a CR2032 3V lithium battery. Please refer to your thermostat’s user manual to confirm the correct battery type.

How often should I change the battery in my Honeywell thermostat?

The frequency of battery replacement can vary depending on the model of your thermostat and its usage. However, it’s a good practice to check your thermostat’s battery level at least once a year. If you notice a low battery warning on your thermostat’s display, it’s time to replace the batteries.

What should I do if my Honeywell thermostat doesn’t work after changing the battery?

If your thermostat doesn’t work after changing the battery, make sure the new batteries are inserted correctly and are fully charged. If the problem persists, you may need to reset your thermostat to its factory settings. If you’re still experiencing issues, it might be time to consult with a professional.

Appliances made simple. 

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