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.
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.
Flue lining systems for use with residential-type and low-heat appliances shall be limited to the following:
- Clay flue lining complying with the requirements of ASTM C315 or equivalent. Clay flue lining shall be installed in accordance with the International Building Code.
- Listed and labeled chimney lining systems complying with UL 1777.
- Other approved materials that will resist, without cracking, softening or corrosion, flue gases and condensate at temperatures up to 1,800°F (982°C).
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.
Plastic pipe and fittings used to vent appliances shall be installed in accordance with the appliance manufacturer's installation instructions.
The application of vents shall be in accordance with Table 802.2.
VENT APPLICATION
VENT TYPES | APPLIANCE TYPES |
Type L oil vents | Oil-burning appliances listed and labeled for venting with Type L vents; gas appliances listed and labeled for venting with Type B vents. |
Pellet vents | Pellet fuel-burning appliances listed and labeled for venting with pellet vents. |
Vents shall terminate not less than 5 feet (1524 mm) in vertical height above the highest connected appliance flue collar.
Exceptions:
- Venting systems of direct vent appliances shall be installed in accordance with the appliance and the vent manufacturer's instructions.
- Appliances listed for outdoor installations incorporating integral venting means shall be installed in accordance with their listings and the manufacturer's installation instructions.
- Pellet vents shall be installed in accordance with the appliance and the vent manufacturer's installation instructions.
Chimney connectors for low-heat appliances shall be of sheet steel pipe having resistance to corrosion and heat not less than that of galvanized steel specified in Table 803.9(1). Connectors for medium-heat appliances and high-heat appliances shall be of sheet steel not less than the thickness specified in Table 803.9(2).
MINIMUM CHIMNEY CONNECTOR THICKNESS FOR LOW-HEAT APPLIANCES
DIAMETER OF CONNECTOR (inches) | MINIMUM NOMINAL THICKNESS (galvanized) (inches) |
5 and smaller | 0.022 (No. 26 gage) |
Larger than 5 and up to 10 | 0.028 (No. 24 gage) |
Larger than 10 and up to 16 | 0.034 (No. 22 gage) |
Larger than 16 | 0.064 (No. 16 gage) |
For SI: 1 inch = 25.4 mm.
MINIMUM CHIMNEY CONNECTOR THICKNESS FOR MEDIUM- AND HIGH-HEAT APPLIANCES
AREA (square inches) | EQUIVALENT ROUND DIAMETER (inches) | MINIMUM THICKNESS (inches) |
0—154 | 0—14 | 0.0575 (No. 16 gage) |
155—201 | 15—16 | 0.075 (No. 14 gage) |
202—254 | 17—18 | 0.0994 (No. 12 gage) |
Greater than 254 | Greater than 18 | 0.1292 (No. 10 gage) |
For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2.
Chimney connectors shall not pass through any floor or ceiling, nor through a fire-resistance-rated wall assembly. Chimney connectors for domestic-type appliances shall not pass through walls or partitions constructed of combustible material to reach a masonry chimney except where one of the following apply:
- The connector is labeled for wall pass-through and is installed in accordance with the manufacturer's instructions.
- The connector is put through a device labeled for wall pass-through.
- The connector has a diameter not larger than 10 inches (254 mm) and is installed in accordance with one of the methods in Table 803.10.4. Concealed metal parts of the pass-through system in contact with flue gases shall be of stainless steel or equivalent material that resists corrosion, softening or cracking up to 1,800°F (980°C).
CHIMNEY CONNECTOR SYSTEMS AND CLEARANCES TO COMBUSTIBLE WALL MATERIALS FOR DOMESTIC HEATING APPLIANCESa, b, c, d
System A (12-inch clearance) | A 3.5-inch-thick brick wall shall be framed into the combustible wall. An 0.625-inch-thick fire-clay liner (ASTM C 315 or equivalent)e shall be firmly cemented in the center of the brick wall maintaining a 12-inch clearance to combustibles. The clay liner shall run from the outer surface of the bricks to the inner surface of the chimney liner. |
System B (9-inch clearance) | A labeled solid-insulated factory-built chimney section (1-inch insulation) the same inside diameter as the connector shall be utilized. Sheet steel supports cut to maintain a 9-inch clearance to combustibles shall be fastened to the wall surface and to the chimney section. liner. The chimney length shall be flush with the masonry chimney liner and sealed to the masonry with water-insoluble refractory cement. Chimney manufacturers' parts shall be utilized to securely fasten the chimney connector to the chimney section. |
System C (6-inch clearance) | A steel ventilated thimble having a minimum thickness of 0.0236 inch (No. 24 gage) having two 1-inch air channels shall be installed with a steel chimney connector. Steel supports shall be cut to maintain a 6-inch clearance between the thimble and combustibles. The chimney connector and steel supports shall have a minimum thickness of 0.0236 inch (No. 24 gage). One side of the support shall be fastened to the wall on all sides. Glass-fiber insulation shall fill the 6-inch space between the thimble and the supports. |
System D (2-inch clearance) | A labeled solid-insulated factory-built chimney section (1-inch insulation) with a diameter 2 inches larger than the chimney connector shall be installed with a steel chimney connector having a minimum thickness of 0.0236 inch (24 gage). Sheet steel supports shall be positioned to maintain a 2-inch clearance to combustibles and to hold the chimney connector to ensure that a 1-inch airspace surrounds the chimney connector through the chimney section. The steel support shall be fastened to the wall on all sides and the chimney section shall be fastened to the supports. Fasteners shall not penetrate the liner of the chimney section. |
For SI: 1 inch = 25.4 mm, 1.0 Btu • in/ft2 • h • °F = 0.144 W/m2 • K.
- Insulation material that is part of the wall pass-through system shall be noncombustible and shall have a thermal conductivity of 1.0 Btu • in/ft2 • h • °F or less.
- All clearances and thicknesses are minimums.
- Materials utilized to seal penetrations for the connector shall be noncombustible.
- Connectors for all systems except System B shall extend through the wall pass-through system to the inner face of the flue liner.
- ASTM C315.
Connectors shall have a minimum clearance to combustibles in accordance with Table 803.10.6. The clearances specified in Table 803.10.6 apply, except where the listing and labeling of an appliance specifies a different clearance, in which case the labeled clearance shall apply. The clearance to combustibles for connectors shall be reduced only in accordance with Section 308.
CONNECTOR CLEARANCES TO COMBUSTIBLES
TYPE OF APPLIANCE | MINIMUM CLEARANCE (inches) |
Domestic-type appliances | |
Chimney and vent connectors | |
Electric and oil incinerators | 18 |
Oil and solid-fuel appliances | 18 |
Oil appliances labeled for venting with Type L vents | 9 |
Commercial, industrial-type appliances | |
Low-heat appliances | |
Chimney connectors | |
Oil and solid-fuel boilers, furnace and water heaters | 18 |
Oil unit heaters | 18 |
Other low-heat industrial appliances | 18 |
Medium-heat appliances | |
Chimney connectors | |
All oil and solid-fuel appliances | 36 |
High-heat appliances | (As determined by the code official) |
Masonry or metal connectors | |
All oil and solid-fuel appliances |
For SI: 1 inch = 25.4 mm.
Horizontal terminations shall comply with the following requirements:
- Where located adjacent to walkways, the termination of mechanical draft systems shall be not less than 7 feet (2134 mm) above the level of the walk-way.
- Vents shall terminate not less than 3 feet (914 mm) above any forced air inlet located within 10 feet (3048 mm).
- The vent system shall terminate not less than 4 feet (1219 mm) below, 4 feet (1219 mm) horizontally from or 1 foot (305 mm) above any door, window or gravity air inlet into the building.
- The vent termination point shall not be located closer than 3 feet (914 mm) to an interior corner formed by two walls perpendicular to each other.
- The vent termination shall not be mounted directly above or within 3 feet (914 mm) horizontally from an oil tank vent or gas meter.
- The bottom of the vent termination shall be located not less than 12 inches (305 mm) above finished grade.
Vertical terminations shall comply with the following requirements:
- Where located adjacent to walkways, the termination of mechanical draft systems shall be not less than 7 feet (2134 mm) above the level of the walk-way.
- Vents shall terminate not less than 3 feet (914 mm) above any forced air inlet located within 10 feet (3048 mm) horizontally.
- Where the vent termination is located below an adjacent roof structure, the termination point shall be located not less than 3 feet (914 mm) from such structure.
- The vent shall terminate not less than 4 feet (1219 mm) below, 4 feet (1219 mm) horizontally from or 1 foot (305 mm) above any door, window or gravity air inlet for the building.
- A vent cap shall be installed to prevent rain from entering the vent system.
- The vent termination shall be located not less than 3 feet (914 mm) horizontally from any portion of the roof structure.
A mechanical draft system shall be permitted to be used with manually fired appliances and fireplaces where such system complies with all of the following requirements:
- The mechanical draft device shall be listed and labeled in accordance with UL 378, and shall be installed in accordance with the manufacturer's instructions.
- A device shall be installed that produces visible and audible warning upon failure of the mechanical draft device or loss of electrical power, at any time that the mechanical draft device is turned on. This device shall be equipped with a battery backup if it receives power from the building wiring.
- A smoke detector shall be installed in the room with the appliance or fireplace. This device shall be equipped with a battery backup if it receives power from the building wiring.
Factory-built chimneys installed in dwelling units with solid fuel-burning appliances shall comply with the Type HT requirements of UL 103 and shall be marked "Type HT" and "Residential Type and Building Heating Appliance Chimney."
Exception: Chimneys for use with open combustion chamber fireplaces shall comply with the requirements of UL 103 and shall be marked "Residential Type and Building Heating Appliance Chimney."
Chimneys for use with open combustion chamber appliances installed in buildings other than dwelling units shall comply with the requirements of UL 103 and shall be marked "Building Heating Appliance Chimney" or "Residential Type and Building Heating Appliance Chimney."