Honeywell RTH9580 Wi-Fi User Manual page 23

Installing your thermostat
8 Switch heating/cooling system ON.
Important!
8a Verify that the C wire is
connected at the thermostat and
at the heating/cooling system.
8b Make sure the heating/cooling
system door is firmly secured.
8c Switch power back ON for your
heating/cooling system at the
breaker box or its power switch.
Circuit
breaker
box
21
or
Heating/cooling
M31544
system power
switch
69-2809EF—03