Honeywell T8400C Product Data page 6

T8400C, T8401C AND T8424C,D ELECTRONIC THERMOSTATS
TERMINAL
FOR STRAIGHT
SCREW INSERTION STRIP
5/16 IN. (8 MM)
G
C
R
W1
Y
Fig. 9. T8424 wiring connections.
The T8400C Thermostats steal power through the heating
and cooling system controls and are adaptable to most 4-wire,
18 to 30 Vac heating-cooling systems.
The T8401C and T8424C,D Thermostats are powered directly
from the system transformer and are adaptable to most
5-wire, 18 to 30 Vac heating-cooling systems. Refer to Fig. 10
through 14 for typical wiring hookups.
T8400C, T8401C
W
Y
G
R
C
2
1
L1
(HOT)
24V
L2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
1
OVERLOAD PROTECTION AS REQUIRED.
2 IN T8401C INSTALLATIONS, CONNECT C TERMINAL.
Fig. 10. T8400C/T8401C heat-cool wiring diagram
in single transformer system with
gas heat/electric cooling.
68-0180-3
FOR WRAPAROUND
STRIP 7/16 IN. (11 MM)
W2
Y2
B
O
M20212
COOLING
CONTACTOR
FAN
HEATING
RELAY
PRIMARY
CONTROL
M11021B
T8400C, T8401C
W
Y
G
R
C
2
1
L1
(HOT)
24V
L2
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
2
IN T8401C INSTALLATIONS, CONNECT C TERMINAL.
Fig. 11. T8400C/T8401C heat-cool wiring diagram
in oil heating/electric cooling system. Oil
primary has its own transformer.
T8424
W1
W2
Y
Y2
G
R
C
1
L1
(HOT)
24V
L2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
1
OVERLOAD PROTECTION AS REQUIRED.
Fig. 12. T8424C,D two-stage heat and two-stage cool
system with manual changeover wiring diagram.
6
COOLING
CONTACTOR
FAN
RELAY
1
L1
T T
(HOT)
OIL PRIMARY
L2 CONTROL
STAGE-ONE
HEATING
1ST STAGE
COOLING
2ND STAGE
COOLING
FAN
STAGE-TWO
RELAY
HEATING
M11022B
M20213