69-0774B—1
3
T874D MULTISTAGE THERMOSTAT AND Q674A,D SUBBASES
H1
FALL
L1
(HOT)
L2
1
RH
W1
W2
G
Y2
Y1
RC
HEAT RELAY 2
HEAT RELAY 1
HEAT
AUTO
COOL
SYSTEM
SWITCH
H1
ANTICIPATOR
C1 ANTICIPATOR
AUTO
ON
FAN SWITCH
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
M11428
L1
(HOT)
L2
1
FAN RELAY
COMPRESSOR
CONTACTOR 2
COMPRESSOR
CONTACTOR 1
1
4
6
8
9
10
11
H2
FALL
C2 ANTICIPATOR
RISE
RISE
C1
C2
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H2 ANTICIPATOR
Fig. 5. Schematic and hookup for T874D Thermostat with Q674D Subbase.
H1
FALL
L1
(HOT)
L2
1
RH
W1
W2
Y2
Y1
RC
HEAT RELAY 2
HEAT RELAY 1
H1
ANTICIPATOR
C1 ANTICIPATOR
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
JUMPER RC, RH FOR SINGLE TRANSFORMER.
M5633
L1
(HOT)
L2
1
COMPRESSOR
CONTACTOR 2
COMPRESSOR
CONTACTOR 1
H2
FALL
C2 ANTICIPATOR
RISE
RISE
C1
C2
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H2 ANTICIPATOR
B
NO FAN SWITCHING
NO SYSTEM SWITCHING
Fig. 6. Schematic and hookup for T874D Thermostat and Q674A Subbase.
Fig. 7. Mounting thermostat on subbase.
THERMOSTAT
MOUNTING POST (2)
M5631
50
6
0 7
0 8
0
50
6
0 7
0 8
0
HE
AT
CO
OL
THERMOSTAT
MOUNTING SLOTS (2)
SUBBASE
THERMOSTAT
CAPTIVE MOUNTING
SCREWS (2)
SETTINGS
Set The Heat Anticipator
Move the indicator to match the current rating of the
primary control. See Fig. 8. When using the T874 Thermo-
stat with two stages of heating, set each heat anticipator to
match its respective primary control current draw. If you
cannot find the current rating on the primary control, or if
further adjustment is necessary, see Note and use the fol-
lowing procedure to determine the current draw of each
stage.
