Honeywell RTH8500 Guide D'installation page 24

Installation Guide
System setup
Furnace filter change reminder
Function This feature displays an alert to remind you to change the furnace filter.
0500
Press
Options: 0
1
2
3
4
5
6
to set the desired reminder interval:
s/t
Off (no reminder to change furnace filter)
Reminder after 10-day run time (about 1 month)
Reminder after 30-day run time (about 3 months)
Reminder after 60-day run time (about 6 months)
Reminder after 90-day run time (about 9 months)
Reminder after 120-day run time (about 1 year)
Reminder after 365-day run time (about 3 years)

Note: Press RESET
to cancel the alert.