Remove Old Thermostat - Honeywell RTH9580 Wi-Fi Quick Start Manual

1.2 Remove old thermostat

faceplate and leave wires
connected
1.2a Take a picture of the wire
connections for later
reference.
1.2b If no wire is connected to a
terminal labeled C or no C
terminal exists on the old
thermostat, view the
Alternate Wiring videos at
wifithermostat.com/videos
Important!
C wire is required
and is the power source for your
thermostat. Without a C wire, your
thermostat will not power up.
Note: You will need a
picture of your wire
connections to wire the
new thermostat.
C
Terminal
designation
If you have an older thermostat with a
sealed mercury tube, see warning page
for proper disposal instructions.
4
M33823A