G24220.127.116.11 (503.10.2.3) Residential-Type Appliance Connectors
Where vent connectors for residential-type appliances are not installed in attics or other unconditioned spaces, connectors for listed appliances having draft hoods, appliances having draft hoods and equipped with listed conversion burners and Category I appliances shall be one of the following:
- Type B or L vent material.
- Galvanized sheet steel not less than 0.018 inch (0.46 mm) thick.
- Aluminum (1100 or 3003 alloy or equivalent) sheet not less than 0.027 inch (0.69 mm) thick.
- Stainless steel sheet not less than 0.012 inch (0.31 mm) thick.
- Smooth interior wall metal pipe having resistance to heat and corrosion equal to or greater than that of Item 2, 3 or 4.
- A listed vent connector.
Vent connectors shall not be covered with insulation.
Exception: Listed insulated vent connectors shall be installed in accordance with the manufacturer's instructions.