Tracing The Auto Fan Circuit; Tracing The Fan On Circuit - Honeywell T874 Product Data

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
THERMOSTAT
H1/C1
ANTICIPATOR
FALL
H1
C1
H2
ANTICIPATOR
H2
FALL
1 POWER SUPPLY. PROVIDE
DISCONNECT MEANS AND
OVERLOAD PROTECTION
AS REQUIRED.
THERMOSTAT
H1/C1
ANTICIPATOR
FALL
H1
C1
H2
ANTICIPATOR
H2
FALL
1 POWER SUPPLY. PROVIDE
DISCONNECT MEANS AND
OVERLOAD PROTECTION
AS REQUIRED.
60-2485—8
SUBBASE
2
FAN SWITCH
3
AUTO
ON
4
5
6
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
Fig. 24. Tracing the auto fan circuit.
SUBBASE
2
FAN SWITCH
3
AUTO
ON
4
5
6
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
Fig. 25. Tracing the fan on circuit.
R
W3
W2
AUX. HT.
LED
(GREEN)
X
EM. HT.
LED (RED)
L
G
O
E
Y
B
R
W3
W2
AUX. HT.
LED
(GREEN)
X
EM. HT.
LED (RED)
L
G
O
E
Y
B
20
SYSTEM COMPONENTS
ODT 1
RTD 1 EHR 1
ODT 2
EHR 2
RTD 1
SYSTEM
RD
MONITOR
FAN RELAY
EM. HT.
CHANGEOVER RELAY
VALVE
LACO
COMPRESSOR
CONTACTOR
SYSTEM COMPONENTS
ODT 1
RTD 1 EHR 1
ODT 2
EHR 2
RTD 1
SYSTEM
RD
MONITOR
FAN RELAY
EM. HT.
CHANGEOVER RELAY
VALVE
LACO
COMPRESSOR
CONTACTOR
L1
(HOT)
L2
1
RTD 2
RTD 3
CHP
M5846
L1
(HOT)
L2
1
RTD 2
RTD 3
CHP
M5847