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§ 27-894 — Thimbles

New York City Administrative Code (current through L.L. 2026/147, enacted September 12, 2026, and amendments effective through October 10, 2026) · NYC Admin. Code § 27-894

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§ 27-894 Thimbles.

(a) When passing through combustible constructions, bent connectors constructed of type B gas vent material shall be installed so that the clearances required by the standard are maintained. (b) Vent connections made of single-wall metal pipe shall not pass through any combustible walls or partitions unless they are guarded at the point of passage by ventilated metal thimbles not smaller than the following: (1) For equipment conforming to standards – four inches larger in diameter than the vent connector. (2) For equipment having draft hoods – six inches larger in diameter than the vent connector. (3) For equipment without draft hoods – twelve inches larger in diameter than the vent connector.