2
3A
If you are unsure about connecting this wire or you do not have any unused wires at the thermostat, contact
Customer Service at (877)288-7707.
Connect a 24 VAC common wire to power the thermostat.
3
Determine if your system has a 24 VAC common wire which is required to power the thermostat.
• If your system is a heat pump, skip to step 4.
a. If your existing thermostat has a terminal named C, COM, X, or B with a wire connected to it, skip to step 4.
b. If your thermostat does not have that terminal, or does not have a wire connected to it, go to step 3a.
a. Locate all unused (disconnected) wires from the
thermostat wire bundle and write down the colors.
• i24V Common wire is typically (not always) colored
blue
Unused wires
Thermostat
wire bundle
b. Go to your HVAC unit and remove the cover(s) to access
the 24 VAC furnace wire terminals.
24 VAC
Furnace
wire
terminals
Furnace
cover
c. Find the 24 VAC common terminal identified with the
letter C, X, B, or COM.
• This terminal may already have a wire connected to it
but it may not be a wire that goes to the thermostat
24 VAC common
terminal
(C, X, B, or COM)
G
W
R
C
d. Locate the thermostat wire bundle inside the furnace
panel.
• This wire bundle is routed from the thermostat,
through the walls, and into the furnace panel.
• This bundle can be identified at the furnace by
checking the wire colors connected and not connected
and comparing to the wire bundle at the thermostat.
Thermostat
wire bundle
G
W
R
C
Unused
wires
e. Find a wire from the thermostat bundle that is unused at
the thermostat and at the furnace.
• It is possible that one of the unused wires at the
thermostat will already be connected to the 24 VAC
common terminal at the furnace. If so, go to step 4.
G
W
R
C
Unused
wire
f. Connect the unused wire to the 24 VAC terminal,
then
replace the furnace cover.
• The 24 VAC common wire is typically (but not always)
blue in color. If the blue wire has been unused, it is
recommended that you use the blue wire.
G
W
R
C
Connect
wire
