UL 307B Ed. 6-2025

Gas-Burning Heating Appliances for Manufactured Homes and Recreational Vehicles - Published Date: November 03, 2025

1.1 These requirements apply to the following gas fuel-burning heating appliances:  a) Direct-vent system appliances for manufactured homes and recreational vehicles; and  b) Vented appliances for manufactured homes other than the direct-vent system type that provide for separation of the combustion system from the atmosphere of the manufactured home by an installation method.  1.2 Requirements for the installation and use of heating appliances in manufactured homes and recreational vehicles are included in:  a) The Department of Housing and Urban Development Manufactured Home Construction and Safety Standards, Chapter II of 24 CFR, Part 3280; and  b) The Standard for Recreational Vehicles, NFPA 501C.  1.3 An appliance designed to burn either oil or gas, and a gas appliance designed to be converted to burn oil by the installation of an optional factory-furnished burner, shall also comply with the requirements in the Standard for Liquid Fuel-Burning Heating Appliances for Manufactured Homes and Recreational Vehicles, UL 307A.  1.4 The term "appliance" as used in this Standard refers to any heating appliance covered by this Standard, such as a warm air central furnace, a wall furnace, a heating boiler, and a water heater.