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  • CHAPTER8
    CHIMNEYS AND VENTS

    SECTION801
    GENERAL

    801.1 Scope.

    This chapter shall govern the installation, maintenance, repair and approval of factory-built chimneys, chimney liners, vents and connectors. This chapter shall govern the utilization of masonry chimneys. Gas-fired appliances shall be vented in accordance with the International Fuel Gas Code.

    801.2 General.

    Every fuel-burning appliance shall discharge the products of combustion to a vent, factory-built chimney or masonry chimney, except for appliances vented in accordance with Section 804. The chimney or vent shall be designed for the type of appliance being vented.

    Exception: Commercial cooking appliances vented by a Type I hood installed in accordance with Section 507.

    801.2.1 Oil-fired appliances.

    Oil-fired appliances shall be vented in accordance with this code and NFPA 31.

    801.3 Masonry chimneys.

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

    801.4 Positive flow.

    Venting systems shall be designed and constructed so as to develop a positive flow adequate to convey all combustion products to the outside atmosphere.

    801.5 Design.

    Venting systems shall be designed in accordance with this chapter or shall be approved engineered systems.

    801.6 Minimum size of chimney or vent.

    Except as otherwise provided for in this chapter, the size of the chimney or vent, serving a single appliance, except engineered systems, shall have a minimum area equal to the area of the appliance connection.

    801.7 Solid fuel appliance flues.

    The cross-sectional area of a flue serving a solid-fuel-burning appliance shall be not greater than three times the cross-sectional area of the appliance flue collar or flue outlet.

    801.8 Abandoned inlet openings.

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

    801.9 Positive pressure.

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

    801.10 Connection to fireplace.

    Connection of appliances to chimney flues serving fireplaces shall be in accordance with Sections 801.10.1 through 801.10.3.

    801.10.1 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.

    801.10.2 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.

    801.10.3 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 provided with access or shall be removable for inspection and cleaning of both the connector and the flue. Listed direct connection devices shall be installed in accordance with their listing.

    801.11 Multiple solid fuel prohibited.

    A solid fuel-burning appliance or fireplace shall not connect to a chimney passageway venting another appliance.

    801.12 Chimney entrance.

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

    801.13 Cleanouts.

    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.

    Exception: Cleanouts shall not be required for chimney flues serving masonry fireplaces, if such flues are provided with access through the fireplace opening.

    801.14 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 and piping on the positive pressure side of the exhauster shall be listed for positive pressure applications as specified by the manufacturer’s installation instructions for the exhauster.

    801.15 Fuel-fired appliances.

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

    801.16 Flue lining.

    Masonry chimneys shall be lined. The lining material shall be compatible with the type of appliance connected, in accordance with the appliance listing and manufacturer’s installation instructions. Listed materials used as flue linings shall be installed in accordance with their listings and the manufacturer’s instructions.

    801.16.1 Residential and low-heat appliances (general).

    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 and labeled 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).

    801.17 Space around lining.

    The space surrounding a flue lining system or other vent installed within a masonry chimney shall not be used to vent any other appliance. This shall not prevent the installation of a separate flue lining in accordance with the manufacturer’s installation instructions and this code.

    801.18 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 801.18.1 through 801.18.4.

    801.18.1 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 the venting of oil-fired appliances to masonry chimneys, the resizing shall be in accordance with NFPA 31.

    801.18.2 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 which would allow the escape of combustion products, including gases, moisture and creosote. Where an oil-fired appliance is connected to an existing masonry chimney, such chimney flue shall be repaired or relined in accordance with NFPA 31.

    801.18.3 Cleanout.

    Masonry chimneys shall be provided with a cleanout opening complying with Section 801.13.

    801.18.4 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.

    801.18.4.1 Fireblocking.

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

    801.19 Multistory prohibited.

    Common venting systems for appliances located on more than one floor level shall be prohibited, except where all of the appliances served by the common vent are located in rooms or spaces that are accessed only from the outdoors. The appliance enclosures shall not communicate with the occupiable areas of the building.

    801.20 Plastic vent joints.

    Plastic pipe and fittings used to vent appliances shall be installed in accordance with the appliance manufacturer’s installation instructions.