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How to replace batteries in Honeywell Thermostat

One of the many modern-day technological miracles is thermostats! Who knew there would be a time when humans would be able to control the temperatures around them? No one did!

Naturally, it’s fascinating to know how these devices work and what makes them so unique. Well, a crucial part of their mechanism is the battery!

And like anything else, even thermostats require replacing these power sources now and then. And if you don’t want to spend time and money on professionals all the time, you should learn how to do it yourself!

Do all Honeywell thermostats use the same batteries?

In a nutshell, no, they don’t. Different Honeywell thermostats have different structures, mechanisms, and compatibility. Some use AA batteries, whereas others are compatible with AAA batteries. So how would you find out which one your thermostat needs? Easy; check your manufacturer manual. You’ll find the ideal batteries compatible with your thermostat.

At this point, most people start wondering, “What’s the most that can happen if I end up buying the wrong batteries?” Well, a lot! Here are some of the most likely occurrences:

  • Your thermostat will not work at all.
  • You won’t be able to get maximum output from it.
  • You will have to replace the batteries again very soon.
  • There could be mechanical damage to your thermostat because of the wrong batteries.
  • Damage to the device will eventually lead you to spend more money getting it fixed.
  • If your thermostat is permanently damaged, you will have to replace it and get a new one.

Interestingly, some Honeywell thermostats don’t require batteries to begin with. They draw power directly from the control voltage (24 volts) in the furnace or the AC unit operating associated controls. These thermostats don’t need batteries, so you don’t have to worry about buying, setting, and replacing them.

And while we are still on the subject of exciting facts about Honeywell thermostats, here is another one: some of these devices can also store digital data. That’s right! However, these devices usually require an internal battery.

How to replace the batteries in your Honeywell thermostats

Even if you don’t know much about machines, changing batteries in thermostats is not as hard as you might think. The following are famous models and series of Honeywell thermostats and how to replace the batteries in each of them:

Honeywell Thermostat 1000 Series And 2000 Series

If you have the vertical 1000 or 2000 series thermostat or the horizontal 2000 series thermostat, the battery replacement method for all these devices is pretty much the same. Here is how to do it in some simple steps:

  • The thermostat has two parts: the wall plate and the control unit.
  • Gently pull the thermostat’s bottom and remove the unit from its wall plate.
  • Turn it over and replace the AAA batteries. You will probably find two of them there.
  • Reverse the process and re-adjust the thermostat back into the wall plate.

You will find an indicator on the machine notifying you that the battery is low. When this indicator turns on, it means that your batteries have about 60 days to live, and then you have to replace them. Generally, you are supposed to switch the batteries every year. But if you’re going away for more than a month, it’s best to do it before you leave.

Honeywell Thermostat 3000 Series And 4000 Series

Both 3000 and 4000 series Honeywell thermostats are very similar. The only difference between them is that the latter is programmable. Batteries are not necessary. Instead, they are optional since the thermostat can easily be hardwired. However, an essential benefit of having batteries is that they provide an adequate backup if the power connection is cut off. Here is how to replace the batteries in these thermostats:

  • Tug at the thermostat’s bottom and gently remove it from its wall plate.
  • Turn it over, and you will find 2 AA batteries inside.
  • Replace them with new ones.
  • You must be sure to complete this process within one minute (60 seconds). Otherwise, the date and time settings will change.
  • Put the thermostat back to its wall plate and ensure it is properly in place.

In the case of these thermostats, you will find a “Replace Batt” warning flashing on the unit, indicating that you need to do it soon. Once the notification comes up, you have about 60 days (or two months) before the batteries go entirely out of charge. Again, you can do it annually or before going on a long trip.

Honeywell Thermostat 5000 Series and 6000 Series

The 5000 and 6000 series of Honeywell thermostats are very similar, so the battery-changing process is the same for both of them. However, once again, the latter is programmable. Here is a straightforward way to take out the old batteries from the thermostat and put in new ones:

  • You will find a battery holder along the right side of your thermostat.
  • Find a release catch along the top of your thermostat unit.
  • Try pressing it down and removing the holder.
  • Once you are successful, take out old batteries from the device and put in the new ones.
  • Then, refit the holder back onto the unit.

You will find a Replace Battery warning flashing very visibly on their displays in these thermostats. Once this warning comes up, you have exactly two months before the batteries will completely dry out.

Honeywell Thermostat TH8000 Series

This particular series of Honeywell thermostats have a unique option called “Backup Batteries.” This feature comes in handy if your unit is directly connected to the main power. In such a case, they provide a good backup if the power fails or the connection is cut off. But as technical as they may sound, replacing their batteries is quite simple:

  • Try pulling the unit away from its wall plate.
  • Turn it over and expose the three AAA batteries.
  • Remove them and add new batteries.
  • Re-adjust your thermostat back to the wall plate.

You will find a Lo Batt warning displayed on the unit for this particular thermostat. Also, the annual maintenance check can reveal how soon your batteries will give up. Then, you can figure out how sooner or later you want to go through with this process. Also, if you’re going away for over a month, it would be a great idea to replace the batteries before you go.

Honeywell Thermostat RTH2300/ RTH221 Series

This series is quite a popular one. However, surprisingly enough, replacing its batteries is no trickier than the rest of the thermostats on the list:

  • Find the power switch and move it to the Auto position.
  • Turn off the heat and cool switch.
  • Gently, try pulling on the thermostat’s bottom and releasing its catches.
  • Unclip the thermostat from its mounting points at the top. Lift the unit forward and upward.
  • You will find two AA batteries inside. Replace them with new ones.
  • Locate the thermostat’s top on its two catches.
  • Lower the thermostat’s bottom ever so gently.
  • Push the unit’s bottom very carefully until you hear a clicking sound. This sound indicates that the thermostat is now in place.

Check its screen to find out whether you need to replace the batteries in the RTH2300/ RTH221 thermostat. If you find a “Lo Batt” notification flashing there, it means that your batteries will go out in about 60 days or so.

Honeywell Thermostat RTH230B

As modern and advanced as this particular thermostat is, replacing its batteries is a very straightforward process:

  • Find the system switch and move it to the Off position.
  • Identify the faceplate, pull it in your direction, and remove it.
  • You will find the battery compartment sitting on the front of your thermostat somewhere around the top.
  • Pull the cover and expose the batteries inside.
  • Remove the old ones and put in the new ones.
  • Now, re-adjust the battery cover until you hear a clicking noise, confirming that it is in the correct position and perfectly fitted.
  • Fit your thermostat back to its wall plate.
  • Once your thermostat successfully performs some tests, it will display an ambient temperature. This means that the thermostat is now working fine.
  • You will then have to reset the day and time settings. However, you don’t have to re-enter them as the program settings are already saved in the unit’s memory chip.

This one flashes an indication on display. After seeing the low battery icon, you have about 120 days to replace them before your thermostat turns off.

Honeywell Thermostat RTH7000 Series

Lastly, this series of Honeywell thermostats are also a crowd-favorite but just as simple to maneuver as all the other ones:

  • Pull the thermostat and gently remove it from its wall plate.
  • Turn it over to find two AA batteries along the top of the unit.
  • Replace them with new ones.
  • Push your device back onto its wall plate.

Like all the other series, this one also displays a “Lo Batt” warning on the screen. It means that you have around one month to change the batteries.

Final Thoughts

If you are still not sure about your thermostat battery compatibility, you can check the Honeywell website out. There you can find the correct manual for your model, assuming you lost the original hard copy.

So, you see, changing batteries in your Honeywell thermostat is not as intimidating as most people assume. It’s a very straightforward process, and you don’t need to have much background knowledge of machines and electronics. However, make sure that you do it carefully and gently, so you don’t end up hurting yourself or damaging your thermostat.

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