Honeywell T8131A, T8131B C, W Y G, R

21 69-0887—1
• Electric Furnace—leave at the
Warm Air Furnace setting (A—
leave in, B—out one turn).
NOTE: This thermostat does not
have a setting for steam/
gravity air. Cycles would
not be long enough for
accurate temperature
control.
IMPORTANT
When using a high
efficiency furnace such as
a 90% or greater AFUE
(Average Fuel Utilization
Efficiency) unit, adjust
screw A out one turn and
leave screw B in.
R
W Y G
B
A
THERMOSTAT BACK
M9199
FOR HIGH EFFICIENCY FURNACE (90%+ AFUE)
ADJUST: SCREW A–OUT ONE TURN
SCREW B–IN
FUEL SWITCH – F POSITION
FE
FUEL SWITCH
WARM AIR
FURNACE
HOT WATER
BOILER
ELECTRIC
FURNACE
A–IN
A–OUT
1 TURN
A–IN
ADJUST SCREWS THROUGH HOLES
TO SELECT OPERATION DESIRED
B–IN
B–IN
B–OUT
1 TURN
FUEL SWITCH
POSITION
F
F
E
HEATING SYSTEM
C