Schematic And Hookup Of T874W With Q674L. Used In Heat Pump Applications - Honeywell T874 Product Data

THERMOSTAT
1
H1
FALL
2
H2
FALL
H1
ANTICIPATOR
H2 ANTICIPATOR
3
4
H3
ANTICIPATOR
5
H3
FALL
6
8
C1
RISE
9
C1 ANTICIPATOR
C2 ANTICIPATOR
10
C2
RISE
11
RESET HEATER
12
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
2 OPTIONAL ECONOMIZER HOOKUP (DOTTED LINES).
Fig. 118. Schematic and hookup of T874W with Q674L. Used in heat pump applications.
SUBBASE
FAN
SWITCH
AUTO
ON
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
AUX. HEAT
LED (GREEN)
139
T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
SYSTEM COMPONENTS
R
DEFROST
RELAY
ECONOMIZER
RELAY
B
HEAT RELAY
CONTACT 1
G
ECONOMIZER
RELAY
ENTHALPY
CONTROL
2
ECONO-
OUTDOOR
MIZER
FAN RELAY 2
RELAY 2
1ST STAGE LOW
PRESSURE LIMIT
Y1
ECONOMISER
RELAY 1
TIME DELAY
HEATER
TIME DELAY
RELAY
Y2
DEFROST
RELAY
2ND STAGE LOW
PRESSURE LIMIT
W
DEFROST
RELAY
CONTACT
O
X
EM. HEAT
LED (RED)
E
C815 OUTDOOR
THERMISTOR
A
L1
(HOT)
L2
1
MOTOR
3
DEFROST
SWITCH
OUTDOOR
FAN RELAY 1
DEFROST
RELAY
DEFROST SWITCH
RELAY
TM1 TM2
OUTDOOR
THERMOSTAT 1
OUTDOOR
FAN RELAY 3
1ST STAGE
SHORT
CYCLE
MOTOR
CONTROL
1
2ND STAGE
SHORT
CYCLE
MOTOR
CONTROL
2
DEFROST
AUXILIARY
RELAY
HEAT RELAY
CONTACT
COOL CHANGEOVER
VALVE
EMERGENCY
HEAT RELAY
M7756
60-2485—8