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