UL 378

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

Draft Equipment

UL 378

1 Scope

1.1 These requirements apply to the design and construction of draft equipment intended to assist in maintaining the desired combustion chamber draft in heating appliances. Draft equipment classifications include draft regulators, automatic damper controls, and draft fans for inducing draft.

1.2 Draft regulators are intended for installation in the breeching or flue pipe of heating appliances where a constant draft is desired, but function to regulate draft only when the draft in the chimney is greater than the draft for which the automatic damper is adjusted.

1.3 Draft regulators intended for use with liquid, combination gas-liquid, or solid fuel-burning equipment, which provide means for the relief of positive pressures in the flue pipe into the adjoining space, provide arrangements for the installer to interlock the assembly with automatic fuel-burning equipment in a manner which will prevent the continued operation of the fuel-burning equipment for more than a brief period of time under conditions of sustained positive draft.

1.4 Draft regulators which provide means for the relief of positive pressures in the flue pipe into the adjoining space and which do not provide means for interlock as described above are intended for use only with commercial-industrial gas-burning equipment not ordinarily equipped with a draft hood.

1.5 Automatic damper controls are designed to automatically regulate the position of dampers installed in the flue pipe or combustion air intake of heating appliances to regulate available draft or combustion air supply to desired values.

1.6 Draft fans are intended for installation in the flue pipe or breeching adjacent to heating appliances or to chimneys to induce or create a draft to supplement the natural draft created by the chimney. Fan units may include automatic dampers or automatic damper controls.

1.7 Requirements for the installation and use of draft equipment are included in the Standards of the National Fire Protection Association for the Installation of Oil-Burning Equipment, NFPA No. 31, and for the National Fuel Gas Code, NFPA No. 54.

1.8 A product that contains features, characteristics, components, materials, or systems new or different from those in use when the standard was developed, and that involves a risk of fire, electric shock, or injury to persons, shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain the level of safety for the user of the product as originally anticipated by the intent of this standard.