Lennox LDT Series Information page 39

Motorized Outdoor Air Damper - The "GLO" mode is also
used when a motorized outdoor air damper is installed in
the system.
NOTE - All economizer modes of operation will
modulate dampers to 55_F (13_C) supply air.
F-Gravity Exhaust Dampers
C1DAMP50C dampers (figure 33) are used in downflow
and LAGEDH are used in horizontal air discharge
applications. LAGEDH gravity exhaust dampers are
installed in the return air plenum . The dampers must be
used any time an economizer or power exhaust fans are
applied to LDT series units. An exhaust hood is furnished
with the gravity exhaust damper.
Gravity exhaust dampers allow exhaust air to be
discharged from the system when an economizer and/or
power exhaust is operating. Gravity exhaust dampers also
prevent outdoor air infiltration during unit off cycle. See
installation instructions for more detail.
LAGED AND LAPEF INSTALLATION
ECONOMIZER
FRESH AIR
HOOD
P18
LAGED GRAVITY
EXHAUST DAMPERS
FIGURE 33
G-C1PWRE10 Power Exhaust Fans
C1PWRE10 power exhaust fans are used in downflow
applications only. C1PWRE10 fans require optional
downflow gravity exhaust dampers and E1ECON15
economizers. Power exhaust fans provide exhaust air
pressure relief and also run when return air dampers are
closed and supply air blowers are operating. Figure 33
shows the location of the power exhaust fans. See
installation instructions for more detail.
LAPEF
POWER EXHAUST
FAN ASSEMBLY
Page 39
H-Optional Cold Weather Kit (Canada only)
Electric heater is available to automatically control the
minimum temperature in the gas burner compartment.
Heater is C.G.A. certified to allow cold weather operation of
unit down to ‐60° F (‐50° C ).
The kit includes the following parts:
1- The strip heater (HR6) is located as close as possible to
the gas valve. The strip heater is rated at 500 Watts
(line voltage).
2- A thermostat mounting box is installed on the vestibule
of the heating compartment. Included in the box are the
following thermostat switches:
a - Thermostat switch (S59) is an auto‐reset SPST N.C.
switch which opens on a temperature drop. The
switch is wired in series with 24v power and the
combustion air
temperature drops below ‐30° F (-35° C) the switch
opens and the gas heat section is de‐energized. The
switch automatically resets when the heating
compartment temperature reaches -10° F (-12° C).
b - Thermostat switch (S60) is an auto‐reset SPST N.C.
switch which opens on a temperature rise. The
switch is wired in series with K125 coil. When the
temperature rises above 20° F (‐7° C) the switch
opens and the electric heater is de‐energized
through K125. The switch automatically resets when
the heating compartment temperature reaches
‐10° F (23.3° C).
c -Thermostat switch (S61) is an auto‐reset SPST N.O.
switch which closes on a temperature drop. The
switch is wired in series with K125 coil. When
temperature drops below 20° F (‐7° C) the switch
closes and electric heater is energized through
K125. The switch automatically opens when heating
compartment temperature reaches 76° F (24° C).
blower switch. When the