Outdoor Air Through Two Vertical Ducts |
| Air From Other Indoor Spaces |
The illustrations shown in this section of the manual are a reference for the openings that provide fresh air into confined spaces only.
Do not refer to these illustrations for the purpose of vent installation. See Venting Installation on page 21 for complete venting installation instructions.
Figure 13
The confined space shall be provided with two permanent vertical ducts, one commencing within 12 inches (300 mm) of the top and one commencing within 12 inches (300 mm) of the bottom of the enclosure. The vertical ducts shall communicate directly with the outdoors. See Figure 13.
Each duct opening shall have a minimum free area of 1 square inch per 4,000 Btu/hr (550 mm2 per kW) of the aggregate input rating of all appliances installed in the enclosure.
When 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 dimension of rectangular air ducts shall be not less than 3 inches.
Figure 14
The confined space shall be provided with two permanent openings, one commencing within 12 inches (300 mm) of the top and one commencing within 12 inches (300 mm) of the bottom of the enclosure. See Figure 14.
Each opening shall communicate directly with an additional room(s) of sufficient volume so that the combined volume of all spaces meets the criteria for an Unconfined Space.
Each opening shall have a minimum free area of 1 square inch per 1,000 Btu/hr (1100 mm2 per kW) of the aggregate input rating of all appliances installed in the enclosure. Each opening shall not be less than 100 square inches (645 cm2).
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