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T8400C AND T8401C ELECTRONIC THERMOSTATS
69-1480-1 4
Slide the FAN switch in the bottom left corner of the
thermostat to select the desired fan setting.
SYSTEM Switch
System switch settings control thermostat operation as
follows:
Cool: The thermostat controls the cooling system.
Off: Both heating and cooling are off.
Heat: The thermostat controls the heating system.
Slide the SYSTEM switch in the bottom right corner of
the thermostat to select the desired system setting.
Fig. 8. Digital display and system
switches (FAN and SYSTEM).
Set Temperature Setpoint
NOTE: Temperature setpoint range is 40° to 99°F (5° to
37°C).
The temperature setpoint and the room temperature are
shown separately on the digital display. The t indicator
points to Set when the temperature setpoint is displayed
and to Room when the room temperature is displayed
.
To set temperature setpoint:
1. Select Heat or Cool by sliding the SYSTEM switch
in the lower right corner of the thermostat to the
desired mode. See Fig. 8.
2. To display the temperature setpoint on the digital
display, press either the s or t key once. The tem-
perature setpoint is displayed for approxi-mately
five seconds as the indicator points to Set and
flashes.
3. To increase the temperature setpoint press the s
key. Each press changes the setpoint one degree;
press and hold to change the setpoint several
degrees.
4. To decrease the temperature setpoint press the t
key. Each press changes the setpoint one degree;
press and hold to change the setpoint several
degrees.
Setting °F/°C Indication and Heat Cycle Rate
NOTE: To save changes to the °F/°C indication and the
heat cycle rate, all seven steps must be com-
pleted.
To set the °F/°C indication and heat cycle rate:
1. If the temperature is displayed in °F, set the tem-
perature setpoint to 52°F. If the room temperature
is displayed in °C, set the temperature setpoint to
11°C.
OPTIONAL SYSTEM CHECKOUT
When in steps 2 and 3 only, the t key can be used to turn
heat or cool outputs on and off. Change the SYSTEM
switch setting to test heat or cool outputs. No action
takes place If the system switch is in the Off position.
Examples:System setting at HEAT: If heat is on, the t
key turns it off; if heat is off, t turns it on.
System setting at COOL: If cool is on, t key
turns it off; if cool is off, t turns it on.
2. Press the st keys simultaneously for more than one
second to light all segments on display and to enter
installer setup mode. When the keys are released,
a two-digit software revision code is displayed.
NOTE: In installer setup mode only, each press of the s
key momentarily displays 01. Each press of the
t key momentarily displays 02. When the keys
are released, these two-digit codes are no
longer displayed.
FAN SYSTEM
Auto On
Cool Off Heat
INCREASE
SETTING
DECREASE
SETTING
SYSTEM SWITCH
FAN SWITCH
TEMPERATURE DISPLAY
M18417
Set
Room
Set
Room
INDICATOR
ROOM TEMPERATURE
SETPOINT TEMPERATURE
M14679
M14680
M14681
M14682
M14683
M14684
M14685
M14686