60-2242—2
6
Fig. 7—Typical wiring diagram for T921B.
T921A,B,E-G
INSTALLATION • SETTING AND ADJUSTING
Fig. 9—Typical wiring diagram for T921F.
L1
(HOT)
L2
1
1
SERIES 90
MODULATING
MOTOR
T921F
M5993
CLASS 2 POWER SUPPLY.
INTERCHANGE B AND W CONNECTIONS TO REVERSE
DIRECTION OF MOTOR TRAVEL.
USE FOR CLASS 2 CIRCUITS. MAKES R TO B ON
TEMPERATURE FALL BELOW THROTTLING RANGE:
2˚ F [1˚ C] DIFFERENTIAL. SEE FIG. 10.
T
R
W
B
T
B
W
R
2
TRANSFORMER
B
W
2
B
W
R
AUXILIARY
SWITCH
2-POSITION
ACTUATOR
3
3
Fig. 10—Typical wiring diagram for T921G.
L1
(HOT)
L2
1
1
SERIES 90
MODULATING
MOTOR
T921G
M5996
CLASS 2 POWER SUPPLY.
INTERCHANGE B AND W CONNECTIONS TO REVERSE
DIRECTION OF MOTOR TRAVEL.
USE FOR CLASS 2 CIRCUITS. MAKES R TO B ON
TEMPERATURE RISE ABOVE THROTTLING RANGE:
1˚ F [0.5˚ C] DIFFERENTIAL. SEE FIG. 11.
T
R
W
B
T
B
W
R
2
TRANSFORMER
B
W
2
B
W
R
AUXILIARY
SWITCH
2-POSITION
ACTUATOR
3
3
L1
(HOT)
L2
1
1
TIMER SWITCH
(OPTIONAL)
SERIES 90
MODULATING
MOTOR
T921E
M5988A
NIGHT
SETBACK
SWITCH
HEATER
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
H TERMINAL IS A BLACK LEADWIRE.
T
R
W
B
T
B
W
R
H
2
2
TRANSFORMER
Fig. 8—Typical wiring diagram for T921E.
L1
(HOT)
L2
1
1
SERIES 90
MODULATING
MOTOR
T921B
M5992
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
INTERCHANGE B AND W CONNECTIONS TO REVERSE
DIRECTION OF MOTOR TRAVEL.
T
R
W
B
T
B
W
R
2
2
TRANSFORMER
B
W
SUMMER-
COOL
WINTER-HEAT
Setting and Adjusting
TEMPERATURE SETTING
Adjust all T921 models at the top of the thermostat for
vertically mounted models and on the left side for horizon-
tally mounted models using the setting adjustment knob or
an Allen wrench (see Fig. 11). The device is shipped with
the temperature setting indicator at the center of the tem-
perature range. Without removing the cover, turn the set-
ting adjustment knob or use an Allen wrench so the indica-
tor is at the desired average room temperature.
ADDITIONAL FEATURES:
T921B SUMMER-WINTER CHANGEOVER
The T921B includes a summer-winter changeover switch.
It is labeled COOL-HEAT. For horizontally mounted
models, this switch is located on the left side of the
thermostat. For vertically mounted models, it is lo-
cated on the top of the thermostat (see Fig. 11).
T921E NIGHT SETBACK
The T921E includes a manual night setback switch
located on the top of the thermostat (see Fig. 11).
