Honeywell T874 Product Data page 127

THERMOSTAT
H1 ANTICIPATOR
FALL
H1
FALL
H2
H2 ANTICIPATOR
RISE
CO
C1 ANTICIPATOR
C1 RISE
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
Fig. 103. Schematic and hookup of T874G with Q674L. Used in heat pump applications.
THERMOSTAT
H1/C1
H1
C1
ANTICIPATOR
FALL
H2 ANTICIPATOR
H2
FALL
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
2
OPTIONAL FIELD WIRE JUMPER TO CYCLE
AUXILIARY HEAT RELAY H1 INSTEAD OF
H2 (FASTER RESPONSE).
Fig. 104. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
SUBBASE
1
FAN
SWITCH
AUTO
ON
2
4
6
SYSTEM
SWITCH
8
SUPL. HT.
9
HEAT
OFF
10
COOL
N.O. SWITCH – INSTALLER ADDED, TO LIGHT SUPL. HT. LED
2
WHEN COMPRESSOR OPERATION IS NOT NORMAL.
SUBBASE
2
FAN
SWITCH
3
AUTO
ON
4
5
6
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
127
T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
COOL CHANGEOVER VALVE
O
G
R
W2
E
2
L
SUPL. HT.
LED (RED)
C
Y
E
EM. HT. LED
(RED)
X
B
R
W2
2
H
Y
G
O
SYSTEM COMPONENTS
1
L1
(HOT)
L2
FAN RELAY
OUTDOOR
THERMOSTAT
HEAT RELAY 1
HEAT RELAY
HEAT RELAY 2
CONTACT 1
HEAT RELAY
HEAT RELAY 3
CONTACT 2
COMPRESSOR
FAULT
COMPRESSOR
CONTACTOR 1
M4665
SYSTEM COMPONENTS
EM. HT. RELAY
"B" RELAY
AUX. HT. RELAY
COMPRESSOR
CONTACTOR
L1
(HOT)
1
L2
Y R
COM
G
R8233B
ELEC. HT.
W
RELAY
EH
O
M4728
60-2485—8