Honeywell CHRONOTHERM T8621A User Manual page 11

Fig. 10—T8621D 2-stage heat/2-stage cool thermostat with HEAT-AUTO-COOL-OFF system and AUTO-ON
fan switching.
THERMOSTAT
LOGIC CIRCUIT
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
2 FOR SINGLE TRANSFORMER SYSTEM JUMPER R AND RC.
NOMINAL 24 Vac POWER MUST BE PRESENT BETWEEN R AND C FOR
3
THERMOSTAT OPERATION.
6
POWER
SUPPLY
SUBBASE
LOGIC/
CONTROL
CIRCUIT
HIGH
LIMIT
HIGH
LIMIT
SYSTEM
SWITCH
HEAT
AUTO
COOL
OFF
FAN
SWITCH
AUTO
ON
4 APPLICABLE ONLY ON T8621D MODEL WITH REMOTE SENSOR.
RECOMMENDED INTERCONNECT CABLE: 18-GAUGE THERMOSTAT
5
CABLE, 200 ft. [61 m] MAXIMUM LENGTH. ROUTE INTERCONNECT
CABLE AWAY FROM SOURCES OF ELECTRICAL NOISE.
DENOTES THERMOSTAT TO SUBBASE INTERCONNECTION.
6
11
INSTALLATION
HEATING
TRANSFORMER
L1
R
(HOT)
2
L2
3
C
HEAT 1
HEAT RELAY 1
W1
HEAT 2 HEAT RELAY 2
W2
S1
S1
S2
S2
S3
S3
5
202905 REMOTE
SENSOR
COOL 2
Y2
COOLING
CONTACTOR 2
COOL 1
Y1
COOLING
CONTACTOR 1
G
FAN RELAY
2
L1
RC
(HOT)
L2
COOLING
TRANSFORMER
M1031E
68-0058—1
T8621A,C,D
1
4
1