Lennox International Inc Elite Series Gas Furnace, EL296UHE Air from Outside

Air from Outside

If air from outside is brought in for combustion and ventila­ tion, the confined space shall be provided with two perma­ nent openings. One opening shall be within 12” (305mm) of the top of the enclosure and one within 12” (305mm) of the bottom. These openings must communicate directly or by ducts with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors or indirectly through vertical ducts. Each opening shall have a mini­ mum free area of 1 square inch per 4,000 Btu (645mm2 per 1.17kW) per hour of total input rating of all equipment in the enclosure (figures 5 and 8). When communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 1 square inch per 2,000 Btu (645mm2 per .59kW) per total input rating of all equip­ ment in the enclosure (See figure 9). 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 Outside)

EQUIPMENT IN CONFINED SPACE

(Inlet Air from Ventilated Crawlspace and Outlet Air to Outside)

Roof Terminated

Exhaust Pipe

					Inlet Air
				(Minimum
Ventilation	Furnace	12 in.(305mm)
Louvers			Above crawl
(Crawl space)			space floor)

Coupling or

3 in. to 2 in. *Intake Debris Screen Provided)

Transition

(Field Provided)

ROOF TERMINATED EXHAUST PIPE

SIDE WALL

TERMINATED EXHAUST PIPE (ALTERNATE LOCATION)

VENTILATION LOUVERS

(Each end of attic)

OUTLET

AIR

FURNACE

	VENTILATION
	LOUVERS
INLET	(For unheated
AIR	crawl space)

* 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 (645mm2 per 1.17kW) per hour of the total input rating of all equipment in the enclosure.

FIGURE 7

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 protec­ tive covering is not known for calculating the size opening required, it may be assumed that wood louvers will have 20 to 25 percent free area and metal louvers and grilles

NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch per 4,000 Btu (645mm2 per 1.17kW) per 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)

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 operation.

EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE

(All Air Through Ventilated Attic)

Roof Terminated

Exhaust Pipe

Ventilation Louvers

Inlet Air

(Minimum

12 in.(305mm) Above

attic floor)

*Intake Debris

Screen

(Provided)

ROOF TERMINATED	VENTILATION LOUVERS
EXHAUST PIPE
	(Each end of attic)

OUTLET

AIR

Furnace

* 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 (645mm2 per 1.17kW) per hour of the total input rating of all equipment in the enclosure.

FIGURE 6

SIDE WALL	FURNACE	INLET AIR
		(Ends 12” above
TERMINATED
		bottom)
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 (645mm2 per 1.17kW) per hour of the total input rating of all equipment in the enclosure.

FIGURE 8

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