Honeywell RTH7400D - Page 8

69-1726—1 8
Step 4. Follow Special Instructions (Cont)
4. If you have only one C and/or C1 wire connected to
your old thermostat, connect this wire to C on the
new thermostat.
Y
C
R
W
OLD THERMOSTAT
WIRE HOLE
M22223
CONNECT TO THE "C" ON THE
NEW THERMOSTAT
WIRE
SCREW
TERMINAL
LETTER
DESIGNATION
G