Tsc-3 Two-Speed Control; Tsc−3 Control - Lennox HP21 Unit Information

TSC-3 Two-Speed Control

All early model HP21 -2 series units (single and three
phase) are equipped with a TSC-3 two-speed control. The
speed-control thermostat (formerly key number S55) has
been removed from the unit and incorporated into the cir-
cuitry of the TSC-3 control (see figure 6). The function and
operating sequence are otherwise identical to the TSC-2
plus the separate thermostat used in previous HP21 units.
The purpose of the speed control thermostat is to force the
compressor to operate on high speed when outdoor tem-
perature is low. It initiates a speed change delay and
automatically energizes high speed when temperature
drops below the setpoint. The setpoint is factory preset and
can be field adjusted.
TSC-3 TWO-SPEED CONTROL
(with built in speed control thermostat)
TEMPERATURE
SENSOR
FIGURE 6
TSC
TWO-SPEED CONTROL
J44
ADJUSTMENT
(potentiometer)
SCREWDRIVER
When temperature rises above the setpoint, the control
initiates a speed change delay and automatically ener-
gizes low speed.
The setpoint can be changed by adjusting the poten-
tiometer shown in figure 6. The potentiometer is factory
set as shown in table 5.
Speed Control Thermostat
Adjustable Range
Cut-In
(Close on Temperature Drop)
Cut-Out
(Open on Temperature Rise)
To adjust the speed control thermostat, insert a small
slot screwdriver into the potentiometer as shown in fig-
ures 6 and 7. To lower the setpoint, turn the
potentiometer counter-clockwise. To raise the setpoint,
turn the potentiometer clockwise. Do not force the po-
tentiometer to turn past its stops; the potentiometer will
be damaged.
TSC-3 TWO-SPEED CONTROL
WINDING TEMPERATURE
SENSOR TERMINALS
TEMPERATURE
TEMPERATURE ADJUSTMENT
SENSOR
The unit wiring diagrams have been revised to reflect the
changes for the HP21-2 (TSC-3), and are shown in section
VII−Wiring Diagrams and Operation Sequence.
Page 10
TABLE 5
Factory
Min. Mid.
Setting
37+2°F 46+2°F 42+2°F 55+2°F
47+2°F 56+2°F 52+2°F 65+2°F
OVERRIDE
BUTTON
(5 minute delay)
(shown in factory position)
FIGURE 7
Max
.