Carrier 58TMA ConfinedSpace Air for Combustion and, Ventilation from an Unconfined Space

VENT THROUGH ROOF￿ (CATEGORY I)

DUCTS TO￿

OUTDOORS

		1 SQ IN.￿
		PER 4000￿
		BTUH*
12″ MAX	D	12″
1 SQ IN.￿	A RETURN￿ VENT￿	MAX

INTERIOR￿

HEATED￿

SPACE

RETURN￿	12″ MAX
AIR
	1 SQ IN.￿
	PER 1000￿
	BTUH* IN DOOR￿
	OR WALL
	UNCONFINED￿
	SPACE
	6″ MIN￿
	(FRONT) †
	1 SQ IN.￿
	PER 1000￿
	BTUH* IN DOOR￿
	OR WALL
	12″ MAX

PER 2000￿			AIR	THROUGH￿			F
BTUH*
				ROOF￿
				(CATEGORY I)
								1 SQ IN.￿
								PER 4000￿
	DUCTS￿				￿CONFINED SPACE			BTUH*
	TO￿							OUTDOORS
	OUTSIDE
								1 SQ IN.￿
								PER 4000￿
								BTUH*
1	SQ IN.￿	B				E	G
PER 2000￿
								12″
BTUH*
	12″ MAX				C			MAX
						12″ MAX

SUPPLY AIR

SUPPLY AIR

*Minimum opening size is 100 sq in. with￿ minimum dimensions of 3 in.

†Minimum of 3 in. when type B-1 vent is used.

A93387

Fig. 3—Confined Space: Air for Combustion and

Ventilation from an Unconfined Space

installed in that space. A confined space MUST have provisions for supplying air for combustion, ventilation, and dilution of flue gases using 1 of the following methods. (See Fig. 3 and Table 2.)

NOTE: In determining free area of an opening, the blocking effect of louvers, grilles, and screens must be considered. If free area of louver or grille design is unknown, assume that wood louvers have a 20 percent free area and metal louvers or grilles have a 60 percent free area. Screens, when used, must not be smaller than 1/4-in. mesh. Louvers and grilles must be constructed so they cannot be closed.

The size of the openings depends upon whether air comes from outside of the structure or an unconfined space inside the structure.

1.All air from inside the structure requires 2 openings (for structures not usually tight):

a.Each opening MUST have at least 1 sq in. of free area per 1000 Btuh of total input for all equipment within the confined space, but not less than 100 sq in. per opening. (See Fig. 3 and Table 2.) The minimum dimension of air openings shall not be less than 3 in.

b.If the building is constructed unusually tight, a permanent opening directly communicating with the outdoors shall be provided. See item 2 below.

c.If furnace is installed on a raised platform to provide a return-air plenum, and return air is taken directly from hallway or space adjacent to furnace, all air for combustion must come from outdoors.

	DUCT￿	1 SQ IN.￿
	TO￿
OUTDOORS		PER 4000￿
		BTUH

*Minimum dimensions of 3 in.

NOTE: Use any of the following￿ combinations of openings:￿

A & B C & D D & E F & G

A93388

Fig. 4—Confined Space: Air for Combustion and

Ventilation from Outdoors

2.Air from outside the structure requires 1 of the following methods:

a.If combustion air is taken from outdoors through 2 vertical ducts, the openings and ducts MUST have at least 1 sq in. of free area per 4000 Btuh of total input for all equipment within the confined space. (See Fig. 4 and Table 2.)

b.If combustion air is taken from outdoors through 2 hori- zontal ducts, the openings and ducts MUST have at least 1 sq in. of free area per 2000 Btuh of total input for all equipment within the confined space. (See Fig. 4 and Table 2.)

c.If combustion air is taken from outdoors through a single opening or duct (horizontal or vertical) commencing within 12 in. of the top of the confined space, opening and duct MUST have at least 1 sq in. of free area per 3000 Btuh of the total input for all equipment within the confined space and not less than the sum of the areas of all vent connectors in the confined space. (See Fig. 4 and Table 2.) Equipment clearances to the structure shall be at least 1 in. from the sides and back and 6 in. from the front of the appliances.

When ducts are used, they must be of the same cross-sectional area as the free area of the openings to which they connect. The minimum dimension of ducts must not be less than 3 in. (See Fig. 4.)

Step 3—Supply-Air Plenum Installation (Downflow)

→DOWNFLOW INSTALLATION

NOTE: This furnace is approved for use on combustible flooring

5 when manufacturer’s accessory floor base Part No.