Sears 153333131, 153333100, 153333030, 153333531, 153333000, 153333530 Allair from Inside Buildings

Combustion Air and Ventilation

for Appliances Located in Unconfined Spaces

Unco_,fined Space is a space whose volume is not Jessthan 50 cubic feet per 1,000 Btu per hour of the aggregateinput rating of all appliances installed in that space_Roomscommunicating 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 spacesin 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, cau]ked, vapor barrier, etc.) additional air may needto be provided using the methods described in Combustion Air and Ventilation for App lances Located in Confined Spaces,b

Combustion Air and Ventilation

for Appl nces Located in Confined Spaces

]. When directly communicating with the outdoors, each opening shah have a minimum free area of t square inch per 4,000 BTU per hour of total input rating of all equip- ment in the enclosure tSeeFigure 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 (SeeFigure 43

Confined Space is a spacewhose volume is less than 50 cubic feet,per 1,000 Btuper hour of the aggregateinput rating of all appliances installedin that space,

Figure 4 t

TER

a. ALLAIR FROM INSIDE BUILDINGS:

(SeePageg Figure 1, and Figure 2 below)

The confined space shall be provided with two permanent

openingscommunicating directly with an additional room(s) of sufficient volume so that the combined volume of all

spacesmeets 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 determina- tion. Each opening shall have a minimum free area of one squareinch per 1,000 8TU per hour of the total input rating of a!l gas utilization equipment in the confined space, but not lessthan I00 square inches. One opening shall com-

mence within 12 inches of the top and one commencing within 12 inchesof the bottom of the enclosure

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FUNOPEN{_IGS

b. ALLAIR FROMOUTDOORS: (see Figures 3-51

The confined space shall be provided with two perma-

nent openings, one commencing within 12 inches of the top and one commencing within 12 inches from the bot- tom 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..

Figure 3 i

t ! ,.l

3.When communicating with the outdoors through horizon- tal ducts, each opening shall have a minimum free area of I square inch per 2,000 13TUper hour of total input rating of all equipment in the enclosure (SeeFigure 5.)

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IFigure 5 J

4, When ducts are used, they shall be of the same cross-sec- tional area as the free area of the openings to _vhich they connect. The minimum short side dimension of rectangular air ducts shall not be lessthan 3 inches (SeeFigure 5.)

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 %inch mesh If the free area through a design of louver or grille is known, it should be used in calculat- ingthe size opening required to provide the free areaspec- ified,. If the-design and free area is not known, it may be assumedthat wood louvers will be 20-25 percent free area and meta] louvers and grilles will have 60-75 percent free area. Louversand grilles shall be fixed in the open position or interlocked with the equipment so that they are opened automatically during equipment operation.

6Special Conditions Created by Mechanical Exhausting or Fireplaces:Operation of exhaust fans, ventilation systems, clothes dryersor fireplaces may create conditions requiring special attention to avoid unsatisfactory operation of installed gas utilization equipment.

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