Page 544 - 2018_IRC

CHAPTER 18

CHIMNEYS AND VENTS

User notes:
About this chapter: Chapter 18 addresses chimneys and vents that serve oil- and solid fuel-fired appliances, including wood pellet appli-
ances. Gas-fired appliances are vented in accordance with Chapter 24. Chapter 10 addresses chimneys for fireplaces and masonry and fac-
tory-built chimneys in general. Note that chimneys and vents are distinct.
Code development reminder: Code change proposals to this chapter will be considered by the IRC—Plumbing/Mechanical Code Develop-
ment Committee during the 2018 (Group A) Code Development Cycle. See explanation on page iv.

SECTION M1801 code and the chimney or vent manufacturer’s installation
GENERAL instructions.
M1801.1 Venting required. Fuel-burning appliances shall Exception: Masonry chimneys equipped with a chim-
be vented to the outdoors in accordance with their listing and ney lining system tested and listed for installation in
label and manufacturer’s installation instructions except chimneys in contact with combustibles in accordance
appliances listed and labeled for unvented use. Venting sys- with UL 1777, and installed in accordance with the
tems shall consist of approved chimneys or vents, or venting manufacturer’s instructions, shall not be required to
assemblies that are integral parts of labeled appliances. Gas- have a clearance between combustible materials and
fired appliances shall be vented in accordance with Chapter exterior surfaces of the masonry chimney. Noncombus-
24. tible firestopping shall be provided in accordance with
M1801.2 Draft requirements. A venting system shall satisfy this code.
the draft requirements of the appliance in accordance with M1801.4 Space around lining. The space surrounding a flue
the manufacturer’s installation instructions, and shall be con- lining system or other vent installed within a masonry chim-
structed and installed to develop a positive flow to convey ney shall not be used to vent any other appliance. This shall
combustion products to the outside atmosphere. not prevent the installation of a separate flue lining in accor-
dance with the manufacturer’s installation instructions and
M1801.3 Existing chimneys and vents. Where an appliance
is permanently disconnected from an existing chimney or this code.
vent, or where an appliance is connected to an existing chim- M1801.5 Mechanical draft systems. A mechanical draft
ney or vent during the process of a new installation, the chim- system shall be used only with appliances listed and labeled
ney or vent shall comply with Sections M1801.3.1 through for such use. Provisions shall be made to prevent the flow of
M1801.3.4. fuel to the equipment when the draft system is not operating.
M1801.3.1 Size. The chimney or vent shall be resized as Forced draft systems and portions of induced draft systems
necessary to control flue gas condensation in the interior under positive pressure during operation shall be designed
of the chimney or vent and to provide the appliance, or and installed to prevent leakage of flue gases into a building.
appliances served, with the required draft. For the venting M1801.6 Direct-vent appliances. Direct-vent appliances
of oil-fired appliances to masonry chimneys, the resizing shall be installed in accordance with the manufacturer’s
shall be done in accordance with NFPA 31. instructions.
M1801.3.2 Flue passageways. The flue gas passageway M1801.7 Support. Venting systems shall be adequately sup-
shall be free of obstructions and combustible deposits and ported for the weight of the material used.
shall be cleaned if previously used for venting a solid or M1801.8 Duct penetrations. Chimneys, vents and vent con-
liquid fuel-burning appliance or fireplace. The flue liner, nectors shall not extend into or through supply and return air
chimney inner wall or vent inner wall shall be continuous ducts or plenums.
and free of cracks, gaps, perforations, or other damage or
deterioration that would allow the escape of combustion M1801.9 Fireblocking. Vent and chimney installations shall
products, including gases, moisture and creosote. be fireblocked in accordance with Section R602.8.
M1801.3.3 Cleanout. Masonry chimneys shall be pro- M1801.10 Unused openings. Unused openings in any vent-
vided with a cleanout opening complying with Section ing system shall be closed or capped.
R1003.17. M1801.11 Multiple-appliance venting systems. Two or
M1801.3.4 Clearances. Chimneys and vents shall have more listed and labeled appliances connected to a common
airspace clearance to combustibles in accordance with this

2018 INTERNATIONAL RESIDENTIAL CODE ® 519
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