7 69-1638—1
Heating System TableStep 5. Wire Thermostat Terminals
Type of System
DI P S w i tc h e s
1 and 2 Fuel Switch
Warm air, gas, or oil heating system with an efficiency rating under 90%.
(The furnace efficiency rating should be on the furnace.)
Use factory setting
1–On; 2–On
F
High-efficiency furnace such as a 90% or greater AFUE (Average Fuel
Utilization Efficiency) unit
1–Off; 2–On F
Hot water boiler 1–Off; 2–On F
Electric furnace 1–On; 2–Off E
Fig. 9. a. Hold thermostat as shown in Fig. 9.
b. Using the labels on the wires, match letter of your old thermostat wire
with the corresponding terminal on the back of your new thermostat.
NOTE: If letters on old thermostat terminals do not match letters on
new thermostat terminals, all old wires may not need connect-
ing to new thermostat. See Special Wiring Instructions section.
Fig. 10. c. Loosen terminal screws and slip each wire beneath its matching
terminal (Fig 10).
d. Securely tighten terminals.
W
Y
G
R
M2012
5
INSERT
STRAIGHT
UNDER
SCREW HEAD
5
/16 in.
(
8 mm)
S
TRIP
END OF WIR
E
VISIBLE HER
E
M20126