Honeywell T8621A User Manual page 3

HIGH
LIMIT
HIGH
LIMIT
SYSTEM
SWITCH
HEAT
AUTO
COOL
OFF
FAN
SWITCH
AUTO
ON
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
2
FOR SINGLE TRANSFORMER SYSTEM JUMPER R AND RC.
3
NOMINAL 24 Vac POWER MUST BE PRESENT BETWEEN R AND C FOR
THERMOSTAT OPERATION.
Fig. 5—T8621C,D 2-stage heat/2-stage cool thermostat
with HEAT-AUTO-COOL-OFF system and
AUTO-ON fan switching. For T8621C, delete
second cooling stage.
HEATING
TRANSFORMER
R
2
3
POWER
C
SUPPLY
H1 HEAT RELAY 1
W1
H2
HEAT RELAY 2
W2
C2
Y2
COOLING
CONTACTOR 2
C1
Y1
COOLING
CONTACTOR 1
G
FAN RELAY
2
RC
COOLING
TRANSFORMER
1
L1
(HOT)
L2
SYSTEM
SWITCH
HEAT
AUTO
COOL
OFF
L1
(HOT)
L2 1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
1
2
ADD RELAY (SPDT) TO ACCOMMODATE COOLING CHANGEOVER.
3
T8621D ONLY.
NOTE:
M1573
Fig. 6—T8621C,D single-stage heat pump thermostats
with cooling changeover. HEAT-AUTO-COOL-
OFF system and AUTO-ON fan switching.
3
R
POWER
HIGH
SUPPLY
LIMIT
C
HIGH
LIMIT
H1
W1
H2
W2
C2 3
Y2
C1
Y1
FAN
SWITCH
AUTO
G
ON
RC
SET CYCLE RATE TO HOT WATER SETTING (3 cph).
THERMOSTAT DOES NOT PROVIDE MINIMUM OFF TIME
IN HEATING.
L1
(HOT) L2
1
SYSTEM
TRANSFORMER
2
K
COOLING
RELAY K
CHANGE-
OVER
COMPRESSOR
CONTACTOR
FAN RELAY
M1575
69-0330—3