If on-length screws A,B are adjusted For longer on-length, readjust screws A,B
to match this system: to match this system:
electric furnace warm air furnace
warm air furnace hot water boiler
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 screw B in.
INSTALLATION
16
17
Adjust System On-Length As Required
STEP 5
STEP 6
Adjust Fan Operation Switch, As Required
■■ The thermostat fan operation switch, labeled
FUEL SWITCH (see figure on page 17) is factory-
set in the “F” position. This is the correct setting for
most systems. If your system is an electric heat
system, set the switch to “E”. The “E” setting will
allow the fan to turn on immediately with the
heating or cooling in a system where the “G”
terminal is connected.
■■ The thermostat on-length is factory-set for a
warm air, gas or oil heating system. If you are
installing it on another type of system, the on-length
must be adjusted accordingly by setting screws A
and B on the back of the thermostat, using the
heating system table in the figure
(page 17) as a guide. The on-length should be
optimized according to the type of system to
minimize room temperature swings. Setting the
screw “out one turn” means turning the screw
approximately 360°, or about one complete turn.
In the rare event that you want a longer on-length, you may readjust the screws as follows:
R
Rc
W Y G
B D
A C
THERMOSTAT BACK
DISPLAY °F
DISPLAY °C
C–IN
C–OUT
1 TURN
FOR HIGH EFFICIENCY FURNACE (90%+ AFUE)
ADJUST: SCREW A–OUT 1 TURN
SCREW B–IN
FUEL SWITCH – F POSITION
F
E
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
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