Sears 153.33655, T53, 33631I Contd, Combustion Air and Ventilation for Appliances Located

Installation Instructions

Combustion Air and Ventilation for Appliances Located in

Unconfined Spaces

Unconfined Space is a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour of the aggregate input rating of all appliances installed in that space. Rooms communicating directly with the space in which the appliances are installed,

through openings not furnished with doors, are considered a part of the unconfined space

In unconfined spaces in buildings, infiltration may be adequate to provide air for combustion, ventilation and dilution of flue gases. However, in buildings of tight construction (for example, weather stripping, heavily insulated, caulked, vapor barrier, etc.), additional air may need to be provided using the methods described in Combustion Air and Ventilation for Appliances Located in Confined Spaces, b.

Combustion Air and Ventilation for Appliances Located in Confined Spaces

Confined Space is a space whose volume is less than 50 cubic feet per 1,000 Btu per hour of the aggregate input rating of all appliances installed in that space.

a. ALL AIR FROM INSIDE BUILDINGS:

(See Page 8 Figure 1, and Figure 2 below)

The confined space shall be provided with two permanent

openings communicating directly with an additional room(s)

of sufficient volume so that the combined volume of all

spaces meets the criteria for an unconfined space. The total

input of all gas utilization equipment installed in the com- bined space shall be considered in making this determination. Each opening shall have a minimum flee area of one square inch per 1,000 BTU per hour of the total input rating of all gas utilization equipment in the confined space, but not less than 100 square inches. One opening shall commence within

12 inches of the top nod one commencing within 12 inches of the bottom of the enclosure.

8 VENT

F_RNAC.EOPENINGS

Ill i _ _

I Figure 2 I

b. ALL AIR FROM OUTDOORS: (see Figures 3-5)

The confined space shall be provided with two permanent

openings, one commencing within 12 inches of the top and one commencing within 12 inches f?om the bottom of the enclosure. The openings shall communicate directly, or by ducts, with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors.

CHIMR_ OR GAg V_NT

VENTILATION LOUVER8

(cont'd)

1.When directly communicating with the outdoors, each open- ing shall have a minimum free area of 1 square inch per 4,000 BTU per hour of total input rating of all equipment in the enclosure. (See Figure 3.)

2.When communicating with the outdoors through vertical ducts, each opening shall have a minimum free area of 1 square inch per 4,000 BTU per hour of total input rating of all equipment in the enclosure. (See Figure 4.)

CHIMNEY OFt _AS VENT

VENTILATION LOUVERS

(each end o_a_tic)

TLET

WATER HEATE FI

FUFtN,a.CE

INLET AJR DLFCT a_ov_ floor_

Figure 4 ]

3.When communicating with the outdoors through horizontal

ducts, each opening shall have a minimum free area of ! square inch per 2,000 BTU per hour of total input rat ng oF all equipment in the enclosure. (See Figure 5.)

_	GHIMNEY Ofl GAS VE I
	WATFFI	_	OUTLET AIF_ DUCT
_	%'&		INLET A_F_DUCT

Figure 5 ]

4.\Vhen ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they connect. The minimum short side dimension of rectangular air ducts shall not be less than 3 inches. (See Figure 5.)

,Louvers and Grilles: In calculating free area, consideration shall be given to the blocking effect of louvers, grilles or screens protecting openings. Screens used shall not be smaller than 5_inch mesh. If the f?ee area through a design of louver or grille is known, it should be used in calculating the size opening required to provide the free area specified. If the design and free area is not lmown, it may be assumed that wood louvers wil! be 20-25 percent free area and metal louvers

and grilles will have 60-75 percent free area. Louvers and grilles shall be fixed in the open position or interlocked with

the equipment so that they are opened automatically during equipment operation.

. Special Conditions Created by Mechanical Exhausting or Fireplaces: Operation of exhaust fans, ventilation systems, clothes dryers or fireplaces may create conditions requiring special attention to avoid unsatisfactory operation of installed gas utilization equipment.

J_LT INLETAIN VENTILATIONLOHVENS

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