801.22 Drains.
MC § 801.22
A drain shall be provided for all chimneys and gas vents to remove rain water and condensation. The drain shall be not less than 1 inch (25.4 mm) in diameter and shall be equipped with an appropriately-sized p-trap with automatic trap seal primer in accordance with Section 1002 of the New York City Plumbing Code or a float drain trap installed in accordance with the manufacturer's requirements. The drain shall be sized by the design engineer and shall be suitable for the chimney area. For listed chimneys and gas vents, the connection tap into the chimney shall be determined by the manufacturer and connected to the drain piping in accordance with the listing and installation instructions. On all outdoor chimneys and gas vents, the connection and drain shall be installed indoors as close as practicable to the chimney base to prevent freezing.
