Lennox International Inc. 43558 - Manual (Page 19)

36
36 OPERATION
Power Switch
The Power switch on the front of the thermostat determines the operating mode of the thermostat.
You may select ON, OFF or Emergency Heat (EM). When the Power Switch is OFF, all outputs are posi-
tively disconnected from the system.
NOTE: Anytime you install or remove the thermostat from the wallplate, slide the Power
Switch to the OFF position to prevent the possibility of a rapid system On-Off.
NOTE: When Emergency Heat (em) is selected on a multi-stage system, the thermostat will
activate both stages of heat (W1 and W2). Thus, the heat control becomes single-stage.
System Selection Key
■ Press to select the desired system.
■ When Auto is selected, the system will change between Heat and Cool
automatically. Refer to the Auto Season Changeover section on page 43.
NOTE: The default system selection at power-on or after a reset
is HEAT. Therefore it is recommended that 2 AAA batteries be
used for backup during power outages.
on off em
system
System
System
System
System
41653_model43558.pmd
37
37 Fan Key
■ Press to set the fan operation.
■ AUTO: the fan will turn on with the system. On a multi-stage system, the
fan is controlled by the system when the Heating system selector has
been set to HG.
ON: the fan will run continuously.
PGM Auto or ON: (Programmable Fan) The fan will select AUTO or ON,
depending on the setting in the programs. Refer to the Program Option
section on page 33.
NOTE: The fan must be set to “PGM” for the fan’s program set-
tings to take effect.
System Indicator Light
When the thermostat activates your system, LED lights are turned on just below the LCD display.
System Monitor This red LCD is controlled by your system and will turn on if there is a problem with your
system. It can only work if you have a connection to the L terminal.
fan
Fan
Fan
Fan
Fan
1 • em
green or red
red
2
yellow
(continued)