Honeywell T874 Product Data page 135

THERMOSTAT
RESET
HEATER H1
ANTICIPATOR
H1
FALL
H2
FALL
H2 ANTICIPATOR
C1
RISE
C1
ANTICIPATOR
C2
ANTICIPATOR
C2
RISE
POWER SUPPLY. PROVIDE DISCONNECT MEANS
1
AND OVERLOAD PROTECTION AS REQUIRED.
Fig. 114. Schematic and hookup of T874D with Q674L. Used in heat pump applications.
SUBBASE
1
2
FAN SWITCH
3
AUTO
ON
4
5
6
7
8
SYSTEM
SWITCH
EM. HT.
HEAT
10
OFF
COOL
11
2 REMOVE FACTORY INSTALLED V-VR JUMPER WHEN CONNECTING
A TWO TRANSFORMER SYSTEM.
135
T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
M2
M
F
V
R
2
L
X
E
VR
SERVICE
LED (RED)
Y
A
SYSTEM COMPONENTS
OUTDOOR
THERMOSTAT
HIGH SPEED
COMPRESSOR
CONTACTOR
LOW SPEED
FAN
COMPRESSOR
RELAY
CONTACTOR
L1
(HOT)
L2
1
COOL
SERVICE
CHANGEOVER
VALVE
EM. HT.
EM. HT. LED
RELAY
(YELLOW)
OUTDOOR
THERMOSTAT
SUPPL. ELEC.
HT. RELAY
SUPPL. ELEC.
HT. RELAY
EM. HT.
RELAY
C815A OUTDOOR
THERMISTOR
M2853
60-2485—8