Honeywell Home Smart RTH6580WF1008 User Manual page 8

Installing your thermostat
Important! The thermostat requires a C wire to operate. The C, or common, wire brings 24
VAC power to the thermostat. Many older mechanical or battery operated thermostats do not
require a C wire.
Do you see a wire connected to the C terminal?
If yes, skip to step 4. If you do not see a C wire, proceed with the
options below:
Option A - Finding the C-Wire:
There might be an extra wire pushed into the wall or wrapped around
the wire bundle. Gently pull the wire bundle out of the wall to check
for unused wires.
If you have an unused wire, connect that wire to the C terminal on
your new thermostat in step 7A or 7B.
Connect the other end of the unused wire to the C terminal on your heating/cooling system
(or the zone panel if your home uses more than one thermostat to control temperature).
Be sure any other wire(s) connected to the C terminal stay securely connected when you
re-tighten the terminal.
Not all heating/cooling equipment use the C label for the 24 VAC common wire. If your
heating/cooling equipment does not have a C terminal, check the system manual or
contact the manufacturer to find out which terminal is the 24 VAC common.
Complete installation by following the remaining steps in this guide.
Option B - Using the C-Wire Power Adapter:
If you do not have an unused wire in the wall, see the C-Wire Power Adapter FREE OFFER
included in the thermostat box. Follow the instructions that come with the C-Wire Power
Adapter and then return to this page. Complete the installation by following the remaining
steps in this guide.
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