Honeywell RTH7400 Series Operating Manual page 21

RTH7400/RTH7500 Series
Grasp thermostat and pull to
remove from wallplate
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 LO BATT
warning begins flashing. The 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.
Insert 2 fresh AA alkaline batteries
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