4000 series include th4110d and th4210d models.

Honeywell thermostat battery replacement. They will flash “replace batt” when the battery needed replacement. Slide off the honeywell thermostat battery cover plate. However, there’s nothing to panic about, and a quick battery replacement will resolve the issue.

Turn off your thermostat, open the battery compartment on the front, and remove the batteries. Remove the old batteries and replace them with new ones. Remove the bad battery from the thermostat by unscrewing all the screws holding it.

Remove the battery holder (top right. Depending on your model, this battery compartment cover. Remove the wall plate from the device.

Put the new batteries in the compartment and slide the protective plate over them. A blank honeywell thermostat display might freak you out. Wait five minutes after removing.

How to change battery in honeywell lyric thermostat model. Switch off the thermostat press and simultaneously gently pull the cover to remove the battery compartment/tray which is located at the top right corner. How to fix a honeywell thermostat that isn’t working disconnect all of the cables from the thermostat.

Locate the batteries by removing the battery compartment tray or cover or by removing the unit’s faceplate. Place the new battery in the position of the older battery. Put your fingers at the bottom of the thermostat.