Batteries should be replaced when they display a low reading indicator or for general maintenance about once a year. Replacing the batteries helps to prevent leakage that can corrode and damage the thermostat.
You will need four new AA batteries; alkaline is best.
It is important to replace the batteries facing in the correct direction. Positive and negative are displayed on the bottom of the battery tray. We suggest replacing them one at at time remembering the direction as they go.
Removing and replacing the cover work best like this.
To remove the cover pull down from the top.
To replace the cover push it straight down over the wall unit. ( See image below ).