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  • CHAPTER5
    CHIMNEYS AND VENTS

    SECTION501 (IFGC)
    GENERAL

    501.1 Scope.

    This chapter shall govern the installation, maintenance, repair and approval of factory-built chimneys, chimney liners, vents and connectors and the utilization of masonry chimneys serving gas-fired appliances. The requirements for the installation, maintenance, repair and approval of factory-built chimneys, chimney liners, vents and connectors serving appliances burning fuels other than fuel gas shall be regulated by the International Mechanical Code. The construction, repair, maintenance and approval of masonry chimneys shall be regulated by the International Building Code.

    501.2 General.

    Every appliance shall discharge the products of combustion to the outdoors, except for appliances exempted by Section 501.8.

    501.3 Masonry chimneys.

    Masonry chimneys shall be constructed in accordance with Section 503.5.3 and the International Building Code.

    501.4 Minimum size of chimney or vent.

    Chimneys and vents shall be sized in accordance with Sections 503 and 504.

    501.5 Abandoned inlet openings.

    Abandoned inlet openings in chimneys and vents shall be closed by an approved method.

    501.6 Positive pressure.

    Where an appliance equipped with a mechanical forced draft system creates a positive pressure in the venting system, the venting system shall be designed for positive pressure applications.

    501.7 Connection to fireplace.

    Connection of appliances to chimney flues serving fireplaces shall be in accordance with Sections 501.7.1 through 501.7.3.

    501.7.1 Closure and access.

    A noncombustible seal shall be provided below the point of connection to prevent entry of room air into the flue. Means shall be provided for access to the flue for inspection and cleaning.

    501.7.2 Connection to factory-built fireplace flue.

    An appliance shall not be connected to a flue serving a factory-built fireplace unless the appliance is specifically listed for such installation. The connection shall be made in accordance with the appliance manufacturer’s installation instructions.

    501.7.3 Connection to masonry fireplace flue.

    A connector shall extend from the appliance to the flue serving a masonry fireplace such that the flue gases are exhausted directly into the flue. The connector shall be accessible or removable for inspection and cleaning of both the connector and the flue. Listed direct connection devices shall be installed in accordance with their listing.

    501.8 Appliances not required to be vented.

    The following appliances shall not be required to be vented:

    1. 1.Ranges.

    2. 2.Built-in domestic cooking units listed and marked for optional venting.

    3. 3.Hot plates and laundry stoves.

    4. 4.Type 1 clothes dryers (Type 1 clothes dryers shall be exhausted in accordance with the requirements of Section 614).

    5. 5.A single booster-type automatic instantaneous water heater, where designed and used solely for the sanitizing rinse requirements of a dishwashing machine, provided that the heater is installed in a commercial kitchen having a mechanical exhaust system. Where installed in this manner, the draft hood, if required, shall be in place and unaltered and the draft hood outlet shall be not less than 36 inches (914 mm) vertically and 6 inches (152 mm) horizontally from any surface other than the heater.

    6. 6.Refrigerators.

    7. 7.Counter appliances.

    8. 8.Room heaters listed for unvented use.

    9. 9.Direct-fired makeup air heaters.

    10. 10.Other appliances listed for unvented use and not provided with flue collars.

    11. 11.Specialized appliances of limited input such as laboratory burners and gas lights.

    Where the appliances listed in Items 5 through 11 above are installed so that the aggregate input rating exceeds 20 British thermal units (Btu) per hour per cubic foot (207 watts per m3) of volume of the room or space in which such appliances are installed, one or more shall be provided with venting systems or other approved means for conveying the vent gases to the outdoor atmosphere so that the aggregate input rating of the remaining unvented appliances does not exceed 20 Btu per hour per cubic foot (207 watts per m3). Where the room or space in which the appliance is installed is directly connected to another room or space by a doorway, archway or other opening of comparable size that cannot be closed, the volume of such adjacent room or space shall be permitted to be included in the calculations.

    501.9 Chimney entrance.

    Connectors shall connect to a masonry chimney flue at a point not less than 12 inches (305 mm) above the lowest portion of the interior of the chimney flue.

    501.10 Connections to exhauster.

    Appliance connections to a chimney or vent equipped with a power exhauster shall be made on the inlet side of the exhauster. Joints on the positive pressure side of the exhauster shall be sealed to prevent flue-gas leakage as specified by the manufacturer’s installation instructions for the exhauster.

    501.11 Masonry chimneys.

    Masonry chimneys utilized to vent appliances shall be located, constructed and sized as specified in the manufacturer’s installation instructions for the appliances being vented and Section 503.

    501.12 Residential and low-heat appliances flue lining systems.

    Flue lining systems for use with residential-type and low-heat appliances shall be limited to the following:

    1. 1.Clay flue lining complying with the requirements of ASTM C 315 or equivalent. Clay flue lining shall be installed in accordance with the International Building Code.

    2. 2.Listed chimney lining systems complying with UL 1777.

    3. 3.Other approved materials that will resist, without cracking, softening or corrosion, flue gases and condensate at temperatures up to 1,800°F (982°C).

    501.13 Category I appliance flue lining systems.

    Flue lining systems for use with Category I appliances shall be limited to the following:

    1. 1.Flue lining systems complying with Section 501.12.

    2. 2.Chimney lining systems listed and labeled for use with gas appliances with draft hoods and other Category I gas appliances listed and labeled for use with Type B vents.

    501.14 Category II, III and IV appliance venting systems.

    The design, sizing and installation of vents for Category II, III and IV appliances shall be in accordance with the appliance manufacturer’s instructions.

    501.15 Existing chimneys and vents.

    Where an appliance is permanently disconnected from an existing chimney or vent, or where an appliance is connected to an existing chimney or vent during the process of a new installation, the chimney or vent shall comply with Sections 501.15.1 through 501.15.4.

    501.15.1 Size.

    The chimney or vent shall be resized as necessary to control flue gas condensation in the interior of the chimney or vent and to provide the appliance or appliances served with the required draft. For Category I appliances, the resizing shall be in accordance with Section 502.

    501.15.2 Flue passageways.

    The flue gas passageway shall be free of obstructions and combustible deposits and shall be cleaned if previously used for venting a solid or liquid fuel-burning appliance or fireplace. The flue liner, chimney inner wall or vent inner wall shall be continuous and shall be free of cracks, gaps, perforations or other damage or deterioration that would allow the escape of combustion products, including gases, moisture and creosote.

    501.15.3 Cleanout.

    Masonry chimney flues shall be provided with a cleanout opening having a minimum height of 6 inches (152 mm). The upper edge of the opening shall be located not less than 6 inches (152 mm) below the lowest chimney inlet opening. The cleanout shall be provided with a tight-fitting, noncombustible cover.

    501.15.4 Clearances.

    Chimneys and vents shall have airspace clearance to combustibles in accordance with the International Building Code and the chimney or vent manufacturer’s installation instructions.

    Exception: Masonry chimneys without the required airspace clearances shall be permitted to be used if lined or relined with a chimney lining system listed for use in chimneys with reduced clearances in accordance with UL 1777. The chimney clearance shall be not less than permitted by the terms of the chimney liner listing and the manufacturer’s instructions.

    501.15.4.1 Fireblocking.

    Noncombustible fireblocking shall be provided in accordance with the International Building Code.