Honeywell T874 Product Data page 153

THERMOSTAT
1
H1
C1
FALL
2
H1/C1
ANTICIPATOR
3
4
H2
ANTICIPATOR
5
6
FALL
H2
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
Fig. 137. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
SUBBASE
FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
153
T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
RTD 1
W3
G
R
W2
AUX. HT.
LED (GREEN)
E
COMP.
FAILURE
EM. HT.
LED
L
(RED)
CHECK
LED (RED)
B
X
LACO
Y
CHANGEOVER VALVE (COOL)
O
SYSTEM COMPONENTS
ODT 1
EHR 1
RTD 2
ODT 2
EHR 2
RDT 3
FAN RELAY
L1
(HOT)
1
L2
EM. HT. RELAY
RTD 1
RD
CHANGEOVER
VALVE (HEAT)
COMPRESSOR
CONTACTOR
CHP
M105A
60-2485—8