14
T8621A,C,D
INSTALLATION
Fig. 13—T8621C,D single stage heat pump with cooling changeover. HEAT-AUTO-COOL-OFF system andAUTO-ON fan switching.4
5
6
RECOMMENDED INTERCONNECT CABLE: 18-GAUGE THERMOSTAT CABLE,
200 ft. [61 m] MAXIMUM LENGTH. ROUTE INTERCONNECT CABLE AWAY
FROM SOURCES OF ELECTRICAL NOISE.
T8621D ONLY.
DENOTES THERMOSTAT TO SUBBASE INTERCONNECTION.
NOTE: SET CYCLE RATE TO HOT WATER SETTING (3 cph). THERMOSTAT
DOES NOT PROVIDE MINIMUM OFF TIME IN HEATING.
M1548C
SYSTEM
TRANSFORMER
R
C
W1
W2
Y2
Y1
G
RC
FAN RELAY
HIGH
LIMIT
HIGH
LIMIT
L1
(HOT) L2
HEAT
AUTO
COOL
SYSTEM
SWITCH
AUTO
ON
FAN
SWITCH
1
S1
S2
S3
S1
S2
S3
202905 REMOTE
SENSOR
3
OFF
COMPRESSOR
CONTACTOR
COOLING
CHANGE-
OVER
H1
H2
C1
C2
RELAY K
K
SUBBASE
LOGIC/
CONTROL
CIRCUIT
6
4
5
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
ADD RELAY (SPDT) TO ACCOMMODATE COOLING CHANGEOVER.
APPLICABLE ONLY ON T8621D MODELS WITH REMOTE SENSOR.
1
2
3
POWER
SUPPLY
THERMOSTAT
LOGIC CIRCUIT