Wiring; Sequence Of Operations - Honeywell T8400C Product Data

THERMISTOR
THERMOSTAT
SENSOR
LOGIC
THERMISTOR
SENSOR
THERMOSTAT
LOGIC
Energy Savings
You can save energy with the T8400C, T8401C and
T8424C,D Thermostats in the heating mode by lowering the
temperature setting 5°F (3°C) to 10°F (5°C) at night and
during the day. You can also save energy in the cooling mode
by raising the temperature setting during the day before you
leave for work or school. Savings can be as high as 7% to
33% depending on your home, where you live, the number of
FAN SWITCH
AUTO
SYSTEM SWITCH
HEAT
OFF
COOL
POWER
SUPPLY
LOGIC AND
CONTROL
Fig. 19. T8400C power 0stealing internal schematic.
FAN SWITCH
SYSTEM SWITCH
HEAT
COOL
POWER
SUPPLY
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
Fig. 20. T8401C hardwired internal schematic.
T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS
ON
MOSFET
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
MOSFET
ON
AUTO
RELAY
OFF
energy saving periods you choose and your energy savings
temperature settings. Refer to the maps in the Operation
section for typical energy savings.

Sequence of Operations

The Fan, Heat and Cool outputs are relay or mosfet
controlled. A loss of ac power or a change in the SYSTEM
switch setting can cause the outputs to turn off. The truth table
shows the sequence of operations for the FAN settings and
SYSTEM modes. See Table 3 Sequence of Operations.
11
L1
(HOT) L2
1
R
FAN RELAY
G
HEAT RELAY
W
COOL RELAY
Y
M10360
R
FAN RELAY
G
1
L1
(HOT)
L2
HEAT RELAY
W
COOL RELAY
Y
C
M10292
68-0180-3