UL 2523
Standard for Solid Fuel-Fired Hydronic Heating Appliances, Water Heaters, And Boilers

DETAILS
Edition Number:1SCC Approved:--
Edition Date:2009-12-22DOD Approved: --
Price Code:BANSI Approved: 2018-03-16
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements apply to factory built manually and/or automatically fueled solid fuel-fired hydronic heating appliances, water heaters and boilers, as defined in Section 5, Glossary, intended to be fixed non-moveable appliances.

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

    1.3 The appliances are provided with an integral chimney and termination or intended for connection to chimneys for residential type and building heating appliances or for 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 National Electrical Code, ANSI/NFPA 70; and the International Mechanical Code (ICC), International Residential Code (ICC) and the Uniform Mechanical Code (IAPMO), as applicable.

  • TABLE OF CONTENTS
    Expand All

    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 Components
          • 3 Units of Measurement
          • 4 Undated References
          • 5 Glossary
        • CONSTRUCTION
          • ALL APPLIANCES
          • 6 General
          • 7 Corrosion Protection
          • 8 Protection of Users and Service Personnel
          • 9 Enclosures
            • 9.1 General
            • 9.2 Accessibility of uninsulated live parts and film-coated wire
            • 9.3 Doors and covers
            • 9.4 Field wiring system connection
          • 10 Field Wiring
            • 10.1 General
            • 10.2 Leads and terminals
          • 11 Internal Wiring
            • 11.1 General
            • 11.2 Methods
            • 11.3 Short-circuit protection
          • 12 Separation of Circuits
          • 13 Bonding for Grounding
          • 14 Mounting of Electrical Components
          • 15 Motors and Motor Overload Protection
          • 16 Overcurrent Protection of High-Voltage Control-Circuit Conductors
            • 16.1 General
            • 16.2 Direct-connected high-voltage control circuit
            • 16.3 Tapped high-voltage control circuits
            • 16.4 Overcurrent-protective devices
          • 17 Overcurrent Protection of Transformers
            • 17.1 High-voltage transformers
            • 17.2 Low-voltage transformers
          • 18 Switches and Controllers
          • 19 Capacitors
          • 20 Electrical Insulating Materials
          • 21 Spacings – High-Voltage Circuits
          • 22 Spacings – Low-Voltage Circuits
          • 23 Control Applications
          • BOILERS
          • 24 Assembly
          • 25 Accessibility for Servicing
          • 26 Casing
          • 27 Radiation Shields or Liners
          • 28 Combustion Chamber
          • 29 Baffles
          • 30 Flue Collar
          • 31 Flue Dampers, Draft Regulators, and Air Shutters
          • 32 Controls
            • 32.1 Application
            • 32.2 Operating controls
            • 32.3 Limit controls
            • 32.4 Liquid level limit controls
            • 32.5 Pressure limit controls
            • 32.6 Temperature limit controls
            • 32.7 Installation of external controls and fittings
          • HYRDRONIC HEATING APPLIANCES AND WATER HEATERS
          • 33 Assembly
          • 34 Accessibility for Servicing
          • 35 Base
          • 36 Casing
          • 37 Radiation Shields
          • 38 Insulation Materials
          • 39 Combustion Chamber
          • 40 Heating Surface Joints
          • 41 Baffles
          • 42 Air Shutters and Flue Collars
          • 43 Materials in Contact with Water
            • 43.1 General
            • 43.2 Dip tubes
            • 43.3 Polymeric storage tank liner
          • 44 Water-Storage Vessels
          • 45 Controls
            • 45.1 Application
            • 45.2 Limit control
            • 45.3 Water-temperature regulating control
        • PERFORMANCE
          • 46 General
          • 47 Test Installation for Standard Clearances
            • 47.1 Enclosure
            • 47.2 Chimney connector
          • 48 Initial Test Conditions
          • 49 Instrumentation
            • 49.1 Draft
            • 49.2 Power measurement
            • 49.3 Speed measurement
            • 49.4 Temperature measurement
          • 50 Test Voltage
          • 51 Solid Fuels and Test Firing Procedures
            • 51.1 General
            • 51.2 Firebrands and hardwood logs
            • 51.3 Charcoal
            • 51.4 Wood pellets
            • 51.5 Automatically Fueled Appliances
          • 52 Water Temperature Control Test – Hydronic Heating Appliance and Water Heater
          • 53 Limit Control Test – Water Heater
          • 54 Limit Control and Low Water Control Test – Boiler
          • 55 Temperature Test
          • 56 Continuous Operation Test
            • 56.1 General
            • 56.2 Continuous operation
            • 56.3 Motor and controller failure
            • 56.4 Loss of electrical power
          • 57 Electrical Tests
            • 57.1 Dielectric test
            • 57.2 Short-circuit test
          • 58 Non-Metallic Dip Tube Test – Water Heaters
            • 58.1 Deformation of weight loss
            • 58.2 Resistance to crushing
            • 58.3 Collapse
          • 59 Hydrostatic Test on Water-Storage Vessels – Water Heater
        • OUTDOOR USE EQUIPMENT
          • CONSTRUCTION
          • 60 General
          • 61 Enclosures
          • 62 Field Wiring Connections
          • 63 Wiring
          • 64 Electrical Insulation Material
          • PERFORMANCE
          • 65 Water Spray Test
          • 66 Metallic Coating Thickness Test – Chromic Acid Dropping Test
        • MANUFACTURING AND PRODUCTION TESTS
          • 67 General
          • 68 Hydrostatic Test on Water-Storage Vessels – Water Heater
          • 69 Production Line Dielectric Voltage-Withstand Test
        • MARKINGS
          • 70 General
          • 71 Nameplate Markings
          • 72 Supplementary Markings
          • 73 Marking Permanency Tests
            • 73.1 General
            • 73.2 Air oven-aging test
            • 73.3 Humidity test
            • 73.4 Unusual-condition exposure test
        • INSTRUCTIONS
          • 74 General
    • Superseded List