Internal Schematic And Typical Hookup Of A T874R Thermostat And Q674L Subbase In A Heat Pump Application - Honeywell T874 Product Data

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
THERMOSTAT
H1/C1
ANTICIPATOR
FALL
H1
C1
H2
ANTICIPATOR
H2
FALL
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2 AUXILIARY HEAT LED AVAILABLE ON SOME MODELS.
Fig. 17. Internal schematic and typical hookup of a T874R Thermostat and Q674L Subbase in a heat pump application.
The thermostat provides two-stage heating and one-stage cooling manual changeover operates on cooling.
60-2485—8
SUBBASE
2
3
FAN SWITCH
AUTO
4
ON
5
6
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
R
W3
W2
AUX. HT.
LED
(GREEN)
2
X
EM. HT.
LED (RED)
L
G
O
E
Y
B
16
SYSTEM COMPONENTS
L2
(HOT) L1
ODT 1
RTD 1 EHR 1
ODT 2
EHR 2
SYSTEM
MONITOR
RD
FAN RELAY
EM. HT.
RELAY
COOL CHANGEOVER
VALVE
LACO
COMPRESSOR
CONTACTOR
1
RTD 2
RTD 3
RTD 1
CHP
M5072A