Lennox ELITE EL195UHE Installation Instructions Manual page 7

inch per 2,000 Btu (645mm
ing of all equipment in the enclosure (See figure 5).It is also
permissible to bring in air for combustion from a ventilated
attic (figure 6) or ventilated crawl space (figure 7).
EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE
(Inlet Air from Crawl Space and Outlet Air to Ventilated Attic)
ROOF TERMINATED
EXHAUST PIPE
SIDE WALL
FURNACE
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
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.
FIGURE 5
EQUIPMENT IN CONFINED SPACE
(Inlet Air from Ventilated Attic and Outlet Air to Outside)
Roof Terminated
Exhaust Pipe
* See table 6 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.
FIGURE 6
2
per .59kW) per total input rat­
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR
VENTILATION
LOUVERS
INLET
(For unheated
AIR crawl space)
2
per 1.17kW) per
Ventilation Louvers
Inlet Air
(Minimum
12 in.(305mm) Above
attic floor)
*Intake Debris
Screen
(Provided)
Furnace
2
per 1.17kW) per
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 6 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.
If air from outside is brought in for combustion and ventila­
tion, the confined space must have two permanent open­
ings. One opening shall be within 12 inches (305 mm) of the
top of the enclosure and one opening within 12 inches (305
mm) of the bottom. These openings must communicate di­
rectly or by ducts with the outdoors or spaces (crawl or at­
tic) that freely communicate with the outdoors or indirectly
through vertical ducts. Each opening shall have a minimum
free area of 1 square inch (645 mm
kW) per hour of total input rating of all equipment in the en­
closure. See figures 5 and 8. When communicating with
the outdoors through horizontal ducts, each opening shall
have a minimum free area of 1 square inch (645 mm
2,000 Btu (.56 kW) per total input rating of all equipment in
the enclosure. See figure 9.
When ducts are used, they shall be of the same cross-sec­
tional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens must
be considered. If the design and free area of protective cov­
ering is not known for calculating the size opening required,
it may be assumed that wood louvers will have 20 to 25 per­
cent free area and metal louvers and grilles will have 60 to
75 percent free area. Louvers and grilles must be fixed in
the open position or interlocked with the equipment so that
they are opened automatically during equipment opera­
tion.
Page 7
Inlet Air
(Minimum
12 in.(305mm)
Above crawl
space floor)
*Intake Debris Screen Provided)
2
per 1.17kW) per
FIGURE 7
2
) per 4,000 Btu (1.17
2
) per