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MC 703 — Outdoor Air

New York City Administrative Code (current through L.L. 2026/147, enacted September 12, 2026, and amendments effective through October 10, 2026) · NYC Mechanical Code § MC 703

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Section MC 703: Outdoor Air

703.1 All air from the outdoors. Where all combustion, ventilation, and dilution air is to be provided by outdoor air, the required combustion, ventilation, and dilution air shall be obtained by direct opening by louver or a duct(s) from the boiler room to the outdoors. Openings connecting the room to the outdoor air shall comply with Sections 703.1.1 through 703.1.2 of this code, and Figures 304.6.1(1), 304.6.1(2), 304.6.1(3) and 304.6.2 of the New York City Fuel Gas Code. The size of the openings connecting the room to the outdoor air supply shall also comply with any applicable rules of the New York City Department of Environmental Protection. 703.1.1 Two-permanent-openings method. Two permanent openings, one commencing within 12 inches (304.8 mm) of the top and one commencing within 12 inches (304.8 mm) of the bottom of the room, shall be provided. The openings shall communicate directly, or by ducts, with the outdoors or spaces that freely communicate with the outdoors as follows: 1. Where directly communicating with the outdoors, or where communicating with the outdoors through vertical ducts, each opening shall have a minimum free area of 1 square inch per 4,000 Btu/h (550 mm2/kW) of total input rating of all equipment in the room. 2. Where communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of not less than 1 square inch per 2,000 Btu/h (1100 mm2/kW) of total input rating of all equipment in the room. 703.1.2 One-permanent-opening method. One permanent opening, commencing within 12 inches (304.8 mm) of the top of the enclosure, shall be provided. The equipment shall have clearances of at least 1 inch (25.4 mm) from the sides and back and 6 inches (152.4 mm) from the front of the appliance. The opening shall directly communicate with the outdoors or through a vertical or horizontal duct to the outdoors or spaces that freely communicate with the outdoors and shall have a minimum free area of 1 square inch per 3,000 Btu/h (734 mm2/kW) of the total input rating of all equipment located in the enclosure, and not less than the sum of the areas of all vent connectors in the space.