UL 391
Standard for Solid-Fuel and Combination-Fuel Central and Supplementary Furnaces

DETAILS
Edition Number:5SCC Approved:--
Edition Date:2010-09-10DOD Approved: --
Price Code:BANSI Approved: 2019-08-19
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements apply to manually fueled, solid-fuel-fired central furnaces. Included are supplementary central furnaces intended for interconnection with forced-air central furnaces utilizing other fuels, and combination oil-fired and solid-fuel-fired, forced-air central furnaces.

    1.2 The furnaces are intended to burn solid fuels, such as wood, coal, or any other biomass fuel, as specified by the manufacturer.

    1.3 The furnaces are intended for connection to chimneys for residential and building heating appliances in compliance with the Standard for Chimneys, Fireplaces, Vents, and Solid Fuel Burning Appliances, NFPA 211, and intended for installation in compliance with the Standard for Installation of Warm Air Heating and Air Conditioning Systems, NFPA 90B; and the National Electrical Code, ANSI/NFPA 70; and applicable mechanical codes such as the BOCA National Mechanical Code, the Standard Mechanical Code, and the Uniform Mechanical Code.

    1.4 A product that contains features, characteristics, components, materials, or systems new or different from those covered by the requirements in this standard, and that involves a risk of fire or of electric shock or injury to persons shall be evaluated using appropriate additional component and end-product requirements to maintain the level of safety as originally anticipated by the intent of this standard. A product whose features, characteristics, components, materials, or systems conflict with specific requirements or provisions of this standard does not comply with this standard. Revision of requirements shall be proposed and adopted in conformance with the methods employed for development, revision, and implementation of this standard.

  • TABLE OF CONTENTS
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    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 Components
          • 3 Units of Measurement
          • 4 Undated References
          • 5 Glossary
        • CONSTRUCTION
          • 6 General
          • 7 Accessibility for Servicing
          • 8 Protection of Users and Service Personnel
          • 9 Base
          • 10 Casings
          • 11 Radiation Shields or Liners
          • 12 Materials in Air-Handling Compartments
          • 13 Air Filters
          • 14 Combustion Chambers
          • 15 Radiators
          • 16 Heating Surface Joints
          • 17 Baffles
          • 18 Flue Collars
          • 19 Disposal of Combustion Products
          • 20 Dampers, Shutters and Draft Regulators
          • 21 Electrical Enclosures
            • 21.1 General
            • 21.2 Doors and covers
            • 21.3 Field wiring system connections
          • 22 Accessibility of Uninsulated Live Parts, Film-Coated Wire and Moving Parts
        • FIELD WIRING
          • 23 General
          • 24 Leads and Terminals
        • INTERNAL WIRING
          • 25 General
          • 26 Methods
          • 27 Short-Circuit Protection
          • 28 Separation of Circuits
          • 29 Bonding for Grounding
        • ELECTRICAL COMPONENTS
          • 30 General
          • 31 Mounting of Electrical Components
          • 32 Electrical Insulating Material
          • 33 Capacitors
          • 34 Receptacles
          • 35 Motors and Motor (Overload) Protection
          • 36 Safety Controls and Circuits
            • 36.1 General
            • 36.2 Fan, limit, and thermostatic damper controls
            • 36.3 Supplementary central furnace controls
            • 36.4 Primary safety control
          • 37 Switches and Controllers
        • SPACINGS
          • 38 High-Voltage Circuits
          • 39 Low-Voltage Circuits
        • PERFORMANCE
          • 40 General
        • TEST INSTALLATION FOR CENTRAL FURNACES
          • 41 Enclosure
          • 42 Chimney Connector
          • 43 Supply-and Return-Air Plenums and Ducts – Forced-Air Furnace
        • TEST INSTALLATION FOR SUPPLEMENTARY CENTRAL FURNACES
          • 44 General
        • INSTRUMENTATION
          • 45 Draft
          • 46 Fuel Input
          • 47 Power Measurement
          • 48 Speed Measurement
          • 49 Static Pressure
          • 50 Temperature Measurement
        • INITIAL TEST CONDITIONS
          • 51 General
          • 52 Static Pressures for Tests
          • 53 Solid Fuels and Test Firing Procedures
            • 53.1 General
            • 53.2 Firebrands
            • 53.3 Charcoal
        • INITIAL TESTS
          • 54 Combustion Test – Oil Burner and Furnace
          • 55 Operation Test
          • 56 Limit Control Cutout Test
            • 56.1 General
            • 56.2 Combination oil-fired and solid-fuel-fired central furnaces
            • 56.3 Solid-fuel-fired central furnaces
            • 56.4 Supplementary central furnaces
        • TEMPERATURE TESTS
          • 57 General
          • 58 Continuous Operation Test
            • 58.1 General
            • 58.2 Continuous operation
            • 58.3 Loss of electrical power
            • 58.4 Simultaneous firing
          • 59 Air Flow Restriction and Disruption Tests
            • 59.1 General
            • 59.2 Preparatory test procedures
            • 59.3 Restricted inlet test
            • 59.4 Fan failure test
            • 59.5 Blocked outlet test
        • OTHER TESTS
          • 60 Delayed Oil Ignition Test
          • 61 Dielectric Voltage Withstand Test
          • 62 Bonding Joint Test
          • 63 Bonding Conductor Test
          • 64 Knockout Security Test
          • 65 Lead Stress Test
          • 66 Surface Burning Test
          • 67 Polymeric Materials Tests
            • 67.1 General
            • 67.2 Aging test
            • 67.3 Flammability test
          • 68 Short Circuit Test
        • MANUFACTURING AND PRODUCTION TESTS
          • 69 General
          • 70 Production Line Dielectric Voltage Withstand Tests
        • MARKING
          • 71 Nameplate
          • 72 Supplementary
          • 73 Instructions
    • Appendix A