How to Change Battery in Honeywell Thermostat-Complete Guide for Different Model

There is a various model of Honeywell thermostat, all model does not require a battery but Honeywell programmable thermostat does need the battery for its LED display. So it is best practice to change the battery of Honeywell Thermostat once in a year. Here, we discuss "How to change battery of Honeywell Thermostat" model by model.

Usually, programmable thermostats containing LED display which require a battery. When it needs a new battery, there will be a low battery warning in the display as, “Replace Battery” or “Batt Lo.” If the battery is not changed, it will show a blank screen and stop working.

For some thermostat models, the battery acts as a back-up power source. Failure to change them will cause date and time settings to disappear.

"How to change battery in Honeywell Thermostat"-this instruction varies from model to model.So make sure you follow the right instruction for your thermostat according to your desire model.

Battery change instruction for different types of model:

  • How to change battery in old Honeywell thermostat?
  • How to change batteries in Lyric Round thermostat?
  • How to change battery in Honeywell 2000 Series?
  • How to change battery in Honeywell 4000 Series?
  • How to change battery Honeywell 5000 and 6000 Series
  • How to change battery Honeywell 8000 Series
  • How to change batteries in Lyric Round thermostat?
  • How to delete battery low command from the display?
  • How to clear Bat Lo signal from the display?

How to change battery in Honeywell Thermostat 2000 Series?

Honeywell 2000series has battery for back-up source. Usually they should be changed once every year.

  1. Turn off the thermostat.
  2. Take out the cover plate from the wall.
  3. Look at the backside and take out the AAA batteries. Insert new batteries.
  4. Put the cover plate back in place.
  5. Keep the thermostat back into the wall plate.
  6. Turn on Thermostat.

How to change battery in Honeywell Thermostat 4000 Series(TH4110D and TH4210D)?

Honeywell TH4110D and Honeywell TH4210D belong to 4000 series. When the battery is low, it shows “ REPLACE BATT”. which means within the next two months you have to change the battery or else it will stop working.

  1. Take out the face plate from the lower side to separate thermostat from wall plate.
  2. From the back side, take out two AA batteries and insert new ones.
  3. Keep the thermostat back into the wall plate.

How to change battery in Honeywell Thermostat 5000 and 6000 Series?

Honeywell TH5110D, TH5320U, TH5220D belong to 5000 series / Focus PRO 5000. While the first model needs two AAA alkaline batteries and the next two need two AA alkaline batteries.


Honeywell 6000 series needs AA batteries.
  1. Push the battery compartment to take out the batteries.
  2. Insert new batteries in it.
  3. Put the battery compartment in place and press it to close it.

How to change battery in Honeywell Thermostat Honeywell 8000 Series​?

Honeywell models TH8110U, TH8320U and TH8321U are in the 8000 series group. It needs three AAA batteries only when it is powered directly to AC supply. It can run three heating and two cooling compartments at a time.

  1. Take out the cover plate.
  2. Take out the batteries from compartment and insert new ones.
  3. Place the cover plate back to the wall plate.

How to change battery in Lyric Round thermostat?

  1. Take out the thermostat from the faceplate on the wall.
  2. Take out the old batteries from battery compartment. Insert new AAA batteries.
  3. Place thermostat back on the wall.

If you are confused between buying the rechargeable CR123A batteries and disposable one​​​

How to delete battery low command from the display?

If the thermostat shows battery low signal even after changing batteries, follow the step below.

  1. Take out the batteries and out them back again but in reverse or opposite position.
  2. Wait for 30 seconds in this way.
  3. Again take out the batteries and insert them in correctly.
  4. The thermostat will successfully reboot and the LOW BAT signal will disappear.
  5. If you see the thermostat is not turned on, then it is likely that thermostat is faulty.
  6. It should be noted that thermostat needs alkaline batteries, if you use rechargeable or lithium batteries, then it will not work.


How to clear Bat Lo signal from display?

If your thermostat is given new alkaline batteries but still shows Bat Lo signal, then the process is already described above.

  1. Take out batteries, put them back reversely and wait for 30 s, put them back again
  2. Clean the terminals in thermostat with electrical contact cleaner and a soft fabric. If you use pointy or hard material like screwdriver or fork to wipe the terminals, it can lead to destroy the coating of thermostat completely.
  3. When the above two steps won’t work, then there is nothing else to do except changing the thermostat with a new one.

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