Lennox ML196DF045XE36B Manual page 26

Intake Piping
The ML196DFE furnace may be installed in either direct
vent or non-direct vent applications. In non-direct vent
applications, when intake air will be drawn into the furnace
from the surrounding space, the indoor air quality must be
considered. Guidelines listed in Combustion, Dilution and
Ventilation Air section must be followed.
Follow the next two steps when installing the unit in Direct
Vent applications, where combustion air is taken from
outdoors and flue gases are discharged outdoors. The
provided air intake screen must not be used in direct
vent applications (outdoors).
1 - Use cement to secure the intake pipe to the inlet air
connector.
2 - Route piping to outside of structure. Continue with
installation following instructions given in general
guide lines for piping terminations and intake and ex­
haust piping terminations for direct vent sections. Re­
fer to table for pipe sizes.
12
Follow the next two steps when installing the unit in Non‐
Direct Vent applications where combustion air is taken
from indoors and flue gases are discharged outdoors.
1 - Use field-provided materials and the factory-provided
air intake screen to route the intake piping as shown in
figure 26. Maintain a minimum clearance of 3" (76mm)
around the air intake opening. The air intake opening
(with the protective screen) should always be directed
forward, or sideways.
2 - If intake air is drawn from a ventilated attic (figure 27)
or ventilated crawlspace (figure 28) the exhaust vent
length must not exceed those listed in table 13. If 3" di­
ameter pipe is used, reduce to 2" diameter pipe at the
termination point to accommodate the debris screen.
3 - Use cement to secure the intake pipe to the connector,
if desired.
TYPICAL AIR INTAKE PIPE CONNECTIONS
NON−DIRECT VENT APPLICATIONS
NOTE - Air intake screen and elbow may be rotated, so that
screen may be positioned to face forward or to either side.
If this unit is being installed in an application with
combustion air coming in from a space serviced by
an exhaust fan, power exhaust fan, or other device
which may create a negative pressure in the space,
take care when sizing the inlet air opening. The in­
let air opening must be sized to accommodate the
maximum volume of exhausted air as well as the
maximum volume of combustion air required for
all gas appliances serviced by this space.
EQUIPMENT IN CONFINED SPACE
(Inlet Air from Ventilated Attic and Outlet Air to Outside)
Roof Terminated
Exhaust Pipe
* See table 13 for maximum vent lengths
NOTE-The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
hour of the total input rating of all equipment in the enclosure.
Page 26
AIR
INTAKE
SCREEN
(Provided)
FIGURE 26
CAUTION
Ventilation Louvers
Inlet Air
(Minimum
12 in.(305mm) Above
attic floor)
*Intake Debris
Screen
(Provided)
Furnace
2
per 1.17kW) per
FIGURE 27