Lennox EL296DFV Installation Instructions Manual page 22

Intake Piping
The EL296DFV 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 or a sheet metal screw to secure the in­
take pipe to the inlet air connector.
2 - If intake air is drawn from a ventilated crawlspace (fig­
ure 30) or ventilated attic (figure 29) the exhaust vent
length must not exceed those listed in table 9. If 3" di­
ameter pipe is used, reduce to 2" diameter pipe to ac­
commodate the debris screen.
3 - 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.
7
CAUTION
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 Crawlspace and Outlet Air to Outside)
Roof Terminated
Exhaust Pipe
Ventilation
Furnace
Louvers
(Crawl space)
Coupling or
3 in. to 2 in.
Transition
(Field Provided)
* See table 9 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.
EQUIPMENT IN CONFINED SPACE
(Inlet Air from Ventilated Attic and Outlet Air to Outside)
Roof Terminated
Exhaust Pipe
* See table 9 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 22
Inlet Air
(Minimum
12 in.(305mm)
Above crawl
space floor)
*Intake Debris Screen Provided)
2
per 1.17kW) per
FIGURE 29
Ventilation Louvers
Inlet Air
(Minimum
12 in.(305mm) Above
attic floor)
*Intake Debris
Screen
(Provided)
Furnace
2
per 1.17kW) per
FIGURE 30