6.2 Type B Vents and Single-Wall Metal Connectors

6.2 Gas Vents and Vent Connectors

Quick Answer: The 2024 IRC distinguishes a listed gas vent from the connector between an appliance and that vent. For gas-appliance vent connectors, use G2427.10; G2427.7 is the section for a single-wall metal-pipe venting system. Listed Type B and Type L vents are installed at the clearance in their listing. A single-wall connector's clearance depends on the appliance row in Table G2427.10.5.

Identify the components first

A gas vent or chimney conveys flue gases outdoors. A vent connector joins the appliance outlet to it unless the vent connects directly. G2426 addresses listed vents, and G2427.10 governs connectors. Type B or Type L labels do not make a product suitable for every fuel or appliance category. Read the listed appliance's permitted vent system and the vent manufacturer's installation instructions, then compare with the 2024 IRC.

Clearances and unconditioned spaces

For a listed appliance with a draft hood or one listed for Type B gas vent, Table G2427.10.5 gives a 6-inch clearance for a single-wall metal-pipe connector. Other rows have different requirements; some vent materials are not permitted for particular appliance classes. Type B and Type L entries may be as listed. Do not teach a universal 9-inch value for every gas appliance without a draft hood, or a universal 1-inch/3-inch value for all Type B/Type L installations.

G2427.10.2.2 requires the relevant connector portion in an attic, crawl space, or other unconditioned space to be listed Type B, Type L, or another listed material with equivalent insulating properties, subject to the section's specific exception. This is more precise than saying every connector is categorically barred from every unconditioned space. Single-wall pipe connectors also face the passage-through-construction restriction in G2427.10.14.

Installation checks

Inspect the listed components, correct joints, rise and routing, support, accessible length, and separation from combustibles. G2427.10 supplies connector details; the appliance and vent listings control model-specific choices. Where a question concerns a single-wall venting system rather than a connector, use G2427.7 and its cross-references instead of transferring connector rules indiscriminately.