Instructions for Installation (cont'd)
b. ALl. AIR FROM OUTDOORS: (see Figures
The confined space shall be provided with two permanent openings, one commencing within 12 inches of the top and one commencing within 12 inches from 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.
3. When communicating with the outdoors through horizon- tal ducts, each opening shall have a minimum free area of 1 square inch per 2,000 BTU per hour of total input rating of all equipment in the enclosure. (See Figure 5.)
IFigure3I
1. When directly communicating with the outdoors, each opening shall have a minimum free area of 1 square inch per 4,000 BTU per hour of total input rating of all equip- ment 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.)
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Figure I
Figure 5 I
4.When ducts are used, they shall be of the same
air ducts shall not be less than 3 inches. (See Figure 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 1/4inch mesh. If the free 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 known, it may be assumed that wood louvers will be
louvers and grilles will have
6.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.
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