Honeywell RTH8500 Manuel D'utilisation page 20

Operating Manual
Battery replacement
Grasp thermostat and pull
to remove from wallplate
Insert 3 fresh AAA alkaline batteries
Batteries are optional (to provide backup
power) if your thermostat was wired to
run on AC power when installed.
Install fresh batteries immediately when
the warning begins flashing. The
L L O O B B A A T T T T
warning flashes about 30 days before
batteries are depleted.
Even if the warning does not appear, you
should replace batteries once a year, or
before leaving home for more than a
month.
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