T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
97 60-24858
Fig. 46. Schematic and hookup of T874A,B,D with Q674B. Used in standard applications..Fig. 47. Schematic and hookup of T874R with Q674B. Used in heat pump applications.
H1
FALL
W1
W2
O
G
Y2
Y1
HEAT RELAY 2
HEAT RELAY 1
HEAT
OFF
COOL
SYSTEM
SWITCH
H1 ANTICIPATOR
C1 ANTICIPATOR
AUTO
ON
FAN
SWITCH
1POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
M2904
B
HEAT CHANGEOVER
VALVE
COOL
CHANGEOVER
VALVE
FAN RELAY
COMPRESSOR
CONTACTOR 2
COMPRESSOR
CONTACTOR 1
1
4
6
8
9
10
11
H2
FALL
C2 ANTICIPATOR
RISE
RISE
C1
C2
L1
(HOT)
L2
1
R
THERMOSTAT SUBBASE SYSTEM COMPONENTS
H2 ANTICIPATOR
L1
(HOT)
L2 1
COOL
HEAT
FALL
O
G
R
W1
Y
H1/C1
ANTICIPATOR
H2
SYSTEM
SWITCH
FAN RELAY
1POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED. M2906
OFF
COOL CHANGEOVER
VALVE
H1
FALL
C1
FAN
SWITCH
AUTO
ON
THERMOSTAT SUBBASE SYSTEM COMPONENTS
1
2
3
4
5
6
AUX. HT.
RELAY
COMPRESSOR
CONTACTOR