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Step 2. Remove Old Thermostat
Fig. 2. a. Turn o ff p ower to the heating/cooling system, either at the furnace or
at the fuse/circuit breaker panel.
b. Remove the cover of your old thermostat (Fig. 2).
c. Unscrew and remove the old thermostat’s mounting plate from the
wall, but do not disconnect the wires.
d. Inspect old thermostat wiring. If wiring meets any of the following
conditions, see special wiring instructions section after Step 7.
Fig. 3. • The old thermostat is a clock thermostat with wires attached to
the C or C1 terminals.
• The old thermostat has six or more wires, excluding wires
attached to C or C1 terminals.
• The old thermostat has three wires.
• There are five wires connected to the old thermostat.
• There are extra wires that are not connected to the old
thermostat.
e. Using enclosed labels, mark wires with letter of terminal it is attached
to on the old thermostat (Fig. 3). Do not label using colors. If labels
do not match letters on old thermostat terminals, see wiring cross ref-
erence table in Special Wiring Instructions section.
Fig. 4. f. Disconnect the wires from the old thermostat and wrap the wires
around a pencil to keep them from falling back into the wall.
NOTE: Remember, if your old thermostat contains mercury, you
must recycle it. See Mercury Notice for more recycling
information.

✓Check your progress

Your wall should now look like Fig. 4.
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WALL OPENING
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