503.10.2.3.3 Medium-heat appliances.
FGC § 503.10.2.3.3
Vent connectors for medium-heat appliances shall be constructed of factory-built medium-heat chimney sections or steel of a thickness not less than that specified in Table 503.10.2.5 and shall comply with the following: 1. A steel vent connector for an appliance with a vent gas temperature in excess of 1,000°F (537.8°C) measured at the entrance to the connector shall be lined with medium-duty fire brick (ASTM C 64, Type F), or the equivalent.
2.The lining shall be not less than 2 1/2 inches (63.5 mm) thick for a vent connector having a diameter or greatest cross-sectional dimension of 18 inches (457.2 mm) or less.
3.The lining shall be not less than 4 1/2 inches (114.3 mm) thick laid on the 4 1/2-inch (114.3 mm) bed for a vent connector having a diameter or greatest cross-sectional dimension greater than 18 inches (457.2 mm).
4.Factory-built chimney sections, if employed, shall be joined together in accordance with the chimney manufacturers' instructions. Table 503.10.2.5Minimum Thickness for Steel Vent Connectors for Medium-Heat Appliances Vent Connector SizeMinimum Thickness(inch)Diameter(inches)Area(square inches)Up to 14 Up to 154 0.053 Over 14 to 16 154 to 201 0.067 Over 16 to 18 201 to 254 0.093 Over 18 Larger than 254 0.123 For SI: 1 inch = 25.4 mm. 1 square inch = 645.16 mm 2 . (Am. L.L. 2023/077, 6/11/2023, eff. 6/11/2023) Editor's note: For related unconsolidated provisions, see Appendix A at L.L. 2023/077.
