UL 441

Please note: All interim revisions for this edition available at time of your purchase will be included.

1 Scope
1.1 These requirements cover Types B and BW gas vents and Types B and BW gas vent roof jacks intended for venting gas appliances equipped with draft hoods to burn only gas. Type B vents are also intended for use with other Category I appliances that specify they are for use with Type B gas vents.
1.2 Gas vents are intended for installation in accordance with the Standards of the National Fire Protection Association for Chimneys, Fireplaces, Vents, and Solid-Fuel Burning Appliances, NFPA 211 and the National Fuel Gas Code, NFPA 54. Gas vents are also intended for installation in accordance with the Department of Housing and Urban Development Mobile Home Construction and Safety Standards, Chapter II of 24 CFR, Part 280 and codes such as the BOCA Basic/National Mechanical Code, the Standard Mechanical Code, and the Uniform Mechanical Code.