Honeywell T874 - Tracing the Changeover Relay Circuit - Diagram; Tracing the Heat 1 and Anticipation Circuit - Diagram

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
17 60-2485—8
Fig. 18. Tracing the changeover relay circuit.
Fig. 19. Tracing the heat 1 and anticipation circuit.
M584
0
L1
(HOT)
L2
1
LACO
CHP
Y
B
E
O
G
L
X
W2
W3
R
ODT 1
RTD 1 EHR 1
RTD 2
ODT 2
EHR 2 RTD 3
RD
SYSTEM
MONITOR
FAN RELAY
COMPRESSOR
CONTACTOR
CHANGEOVER
VALVE
EM. HT.
RELAY
RTD 1
AUX. HT.
LED
(GREEN)
EM. HT.
LED (RED)
FAN SWITCH
ON
AUTO
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
H2
FALL
H1
FALL
C1
2
3
4
5
6
H1/C1
ANTICIPATOR
H2
ANTICIPATOR
1
POWER SUPPLY. PROVIDE
DISCONNECT MEANS AND
OVERLOAD PROTECTION
AS REQUIRED.
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
M5841
L1
(HOT
)
L2
1
LACO
CHP
Y
B
E
O
G
L
X
W2
W3
R
ODT 1
RTD 1
EHR 1
RTD 2
ODT 2
EHR 2 RTD 3
RD
SYSTEM
MONITOR
FAN RELAY
COMPRESSOR
CONTACTOR
CHANGEOVER
VALVE
EM. HT.
RELAY
RTD 1
AUX. HT.
LED
(GREEN)
EM. HT.
LED (RED)
FAN SWITCH
ON
AUTO
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
H2
FALL
H1
FALL
C1
2
3
4
5
6
H1/ C1
ANTICIPATOR
H2
ANTICIPATOR
1
POWER SUPPLY. PROVIDE
DISCONNECT MEANS AND
OVERLOAD PROTECTION
AS REQUIRED.
THERMOSTAT SUBBASE
SYSTEM COMPONENTS