// CODE SNIPPET
701.6.1 Two Permanent Openings Method
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Two
permanent openings, one commencing within 12 inches
(305 mm) of the top of the enclosure and one commencing
within 12 inches (305 mm) of the bottom of the enclosure,
shall be provided. The openings shall communicate
directly, or by ducts, with the outdoors or spaces that
freely communicate with the outdoors as follows:
FIGURE 701.6.1(1)
COMBUSTION AIR FROM OUTDOORS INLET AIR FROM VENTILATED CRAWL SPACE AND OUTLET AIR TO VENTILATED ATTIC [NFPA 54: FIGURE A.9.3.3.1(1)(a)]
FIGURE 701.6.1(2)
COMBUSTION AIR FROM OUTDOORS THROUGH VENTILATED ATTIC [NFPA 54: FIGURE A.9.3.3.1(1)(b)]
FIGURE 701.6.1(3)
COMBUSTION AIR FROM OUTDOORS THROUGH HORIZONTAL DUCTS [NFPA 54: FIGURE A.9.3.3.1(2)]
- Where directly communicating with the outdoors or where communicating to the outdoors through vertical ducts, each opening shall have a free area of not less than 1 square inch per 4000 Btu/h (0.0005 m2/kW) of total input rating of appliances in the enclosure. [See Figure 701.6.1(1) and Figure 701.6.1(2)]
- Where communicating with the outdoors through horizontal ducts, each opening shall have a free area of not less than 1 square inch per 2000 Btu/h (0.001 m2/kW) of total input rating of appliances in the enclosure. [See Figure 701.6.1 (3)] [NFPA 54:9.3.3.1]
COMBUSTION AIR FROM OUTDOORS INLET AIR FROM VENTILATED CRAWL SPACE AND OUTLET AIR TO VENTILATED ATTIC [NFPA 54: FIGURE A.9.3.3.1(1)(a)]
COMBUSTION AIR FROM OUTDOORS THROUGH VENTILATED ATTIC [NFPA 54: FIGURE A.9.3.3.1(1)(b)]
COMBUSTION AIR FROM OUTDOORS THROUGH HORIZONTAL DUCTS [NFPA 54: FIGURE A.9.3.3.1(2)]
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