Honeywell T8621A User Manual page 4

POWER
SUPPLY
HIGH
LIMIT
HIGH
LIMIT
SYSTEM
SWITCH
HEAT
AUTO
COOL
OFF
C1
FAN
SWITCH
AUTO
ON
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
2
T8621D ONLY.
NOTE: SET CYCLE RATE TO HOT WATER SETTING (3 cph).
THERMOSTAT DOES NOT PROVIDE MINIMUM OFF TIME
IN HEATING.
Fig. 7—T8621C,D single-stage heat pump thermostats
with heating changeover. HEAT-AUTO-COOL-
OFF system and AUTO-ON fan switching.
L1
(HOT)
1
SYSTEM
TRANSFORMER
R
C
HEATING
CHANGEOVER
H1
W1
COMPRESSOR
CONTACTOR
H2
W2
2
C2
Y2
Y1
FAN RELAY
G
RC
L2
FAN
OPERATION
SWITCH
3
ELECTRIC
2
NON-
ELECTRIC
SYSTEM
SWITCH
HEAT
OFF
COOL
FAN
SWITCH
AUTO
ON
POWER SUPPLY. PROVIDE DISCONNECT MEANS
1
AND OVERLOAD PROTECTION AS REQUIRED.
M1576
2
FOR GAS OR OIL APPLICATIONS OR ELECTRIC HEAT
APPLICATIONS WHERE THE FAN OPERATION IS CONTROLLED
INDEPENDENTLY OF THE THERMOSTAT (AUTO FAN OPERATES
WITH Y1 ONLY). TWO TRANSFORMERS MAY BE USED. SET
SWITCH TO NONELECTRIC POSITION.
FOR ELECTRIC HEAT APPLICATIONS (AUTO FAN OPERATES
3
WITH W1 AND Y1), USE ONLY ONE TRANSFORMER; JUMPER
R AND RC. SET SWITCH TO ELECTRIC POSITION.
4 NOMINAL 24 VAC POWER MUST BE PRESENT BETWEEN
R AND C FOR THERMOSTAT OPERATION.
Fig. 8—T8621D 2-stage heat/2-stage cool manual
changeover thermostat with auto fan on heat
and cool; convertible to auto fan on cool only.
HEAT-OFF-COOL system and AUTO-ON fan
switching.
4
HEATING
TRANSFORMER
R
4
POWER
C
SUPPLY
HIGH
LIMIT
HIGH
LIMIT
W1
HEAT 1
W2
HEAT 2
B
O
Y2
COOL 1
COOL 2
Y1
G
RC
L1
(HOT) L2
1
STAGE 1
HEAT RELAY
STAGE 2
HEAT RELAY
HEATING DAMPER OR
CHANGEOVER RELAY
COOLING DAMPER OR
CHANGEOVER RELAY
STAGE 2
COOLING RELAY
STAGE 1
COOLING RELAY
FAN RELAY
3
COOLING
TRANSFORMER
1
L1 L2
(HOT)
M13444