Honeywell T874G Installation Instructions Manual page 6

Fig. 8—Internal schematic and typical wiring diagram for Y594G1526 (T874G1626/Q674F1436); auto
changeover in heating.
THERMOSTAT
H1 ANTICIPATOR
FALL
H1
H2
ANTICIPATOR
H2
FALL
FALL
CHANGEOVER
C1
ANTICIPATOR
C1
1
RISE
Fig. 9—Internal schematic and typical wiring diagram for T874D1165, T874E1016/Q674F1543. Exact
replacement for York model no. 2TB04700524.
THERMOSTAT
H1
FALL
H1 ANTICIPATOR
H2
H2
ANTICIPATOR
FALL
C1
RISE
C1 ANTICIPATOR
C2 ANTICIPATOR
C2
RISE
69-0435—10
2
FAN SWITCH
3
AUTO
4
ON
5
SYSTEM
SWITCH
OFF
7
EM. HT.
HEAT
AUTO
8
COOL
9
10
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
4
6
8
9
10
11
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2
LED IS NOT LABELED. JUMPER W2 TO X FOR AUXILIARY HEAT INDICATION. JUMPER E TO X FOR
EMERGENCY HEAT INDICATION. CONNECT SYSTEM MONITOR TO X TO IDENTIFY WHEN SYSTEM
NEEDS TO BE CHECKED.
SUBBASE
AUX. HEAT
LED (GREEN)
EM. HT.
LED (RED)
SUBBASE
FAN
SWITCH
AUTO
ON
SYSTEM
SWITCH
OFF
EM. HT.
HEAT
AUTO
COOL
6
SYSTEM COMPONENTS
R
ODT 1
RTD 1 EHR 1
ODT 2
EHR 2
W2
X
COMPRESSOR
RD
FAILURE
L
G
B
HEAT
CHANGEOVER
VALVE
E
EHT1
LACO
Y
COMPRESSOR
CONTACTOR
SYSTEM COMPONENTS
HEAT RELAY 1
W1
HEAT RELAY 2
W2
R
X
LED 2
(RED)
B
EM. HEAT RELAY
E
FAN RELAY
G
COMPRESSOR
CONTACTOR 2
Y2
COMPRESSOR
CONTACTOR 1
Y1
L2
(HOT) L1
1
RTD 2
RTD 3
RTD 1
FAN RELAY
EM. HT.
RELAY
CHP
M1592A
L1
(HOT)
L2
1
M2982A