Mounting Thermostat To Wallplate; Operation; Setting Fan And System Switches; Fan Switch - Honeywell T8400C1099 Installation Instructions Manual

T8400C1099, T8401C1031 ELECTRONIC THERMOSTATS
G
C
R
W
Y
1
HEAT
L1
RELAY
(HOT)
24V
L2
TRANSFORMER
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
Fig. 9. Typical hookup of T8401C1031 in heat-cool
G
C
R
W
3
Y
1
COMPRESSOR
L1
(HOT)
24V
L2
TRANSFORMER
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
2 CAN BE USED FOR CHANGEOVER VALVE ON
SINGLE-STAGE HEAT PUMP SYSTEMS.
3
FIELD INSTALLED JUMPER.
Fig. 10. Typical hookup of T8401C1031 in single-
stage heat pump system.

Mounting Thermostat to Wallplate

1. Engage the tabs at the top of the thermostat and
wallplate.
2. Swing down the thermostat and press the lower
edge of the thermostat onto the wallplate to latch.
See Fig. 11.
69-1484-2
B
O
COOL FAN
RELAY RELAY
M20881
system.
2
HEAT
CHANGEOVER
B
2
COOL
CHANGEOVER
O
FAN
RELAY
M20882
Fig. 11. Mounting thermostat wallplate.

OPERATION

Setting FAN and SYSTEM Switches

Fan and system settings are controlled manually by
using the switches located at the bottom of the
thermostat case. See Fig. 12.

FAN Switch

Fan switch settings are:
On: The fan runs continuously. Use for improved air
circulation and air quality.
Auto: Normal setting for most homes. In cooling, the
fan starts and stops with the cooling equipment. In
heating, the fan is controlled directly by the heating
equipment and may start a few minutes after the
heating equipment turns on (on most systems).
When using an electric heat thermostat, the fan
starts and stops with the heating equipment.
Slide the FAN switch in the bottom left corner of the
thermostat to select the desired fan setting.
4
DASHED LINES INDICATE TABS
ON BACK OF THERMOSTAT
A
ENGAGE TABS AT TOP OF THERMOSTAT
WITH SLOTS ON MOUNTING PLATE.
B
PRESS LOWER EDGE OF
CASE TO LATCH.
M14677