User's Manual

5 69-2715EF—07
Important! This thermostat requires a C, or common, wire for power. The C, or common,
wire brings 24 VAC power to the thermostat. If you are replacing an existing thermostat,
it might not have a C wire connected to it. Many older mechanical or battery operated
thermostats do not require a C wire. See the C Wire Addendum document included in
this package for more information.
Note: Not all heating/cooling systems label the 24 VAC common C. Check your
system manual or contact the manufacturer to find out which terminal is the 24 VAC
common.
View the Alternate Wiring videos at honeywellhome.com/wifi-thermostat
Wiring
For conventional heating/cooling systems (natural gas, oil or electric furnace, air
conditioner), see page 5. See “Glossary” on page 33 for further definition.
For a heat pump system, see page 6. See “Glossary” on page 33 for further
definition.
Installing your thermostat
MCR34540
C
K
Rc
R
W-
O/B
Y
G
W2-
Aux/E
Y2
L
W
Y
G
R
C
Wiring (Conventional System)
6A Wire the thermostat to your
conventional system.
a Starting with the C Wire, match the
sticky tag on the wire to the terminal
labels.
You must have a C wire.
b
Straighten wire and gently slide into
terminal hole until it clicks into place.
(If you need to remove a wire, use a
pen tip to press the terminal release
and then pull wire out.)
Note: Refer to the wiring picture you took
in Step 2.
Tip: To make it easier to slide the wire
into place, use a pen tip to hold down the
terminal release.
Note: The wiring for your
application might be different
than the wiring shown below.
Labels don’t match?
See alternate wiring keys
on pages 78.
Terminal release
Remove jumper loop ONLY if
you have both R and Rc wires.
EXAMPLE WIRING
Yours may look different