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Section M1803 Chimney and Vent Connectors
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CHIMNEY AND VENT CONNECTOR CLEARANCES TO COMBUSTIBLE MATERIALSa
M1803.1 General
M1803.2 Connectors for Oil and Solid Fuel-Burning Appliances
Connectors for oil and solid fuel-burning appliances shall be constructed of factory-built chimney material, Type L vent material or single-wall metal pipe having resistance to corrosion and heat and thickness not less than that of galvanized steel as specified in Table M1803.2.
TABLE M1803.2
THICKNESS FOR SINGLE-WALL METAL PIPE CONNECTORS| DIAMETER OF CONNECTOR (inches) |
GALVANIZED SHEET METAL GAGE NUMBER | MINIMUM THICKNESS (inch) |
| Less than 6 | 26 | 0.019 |
| 6 to 10 | 24 | 0.024 |
| Over 10 through 16 | 22 | 0.029 |
For SI: 1 inch = 25.4 mm.
M1803.3 Installation
Vent and chimney connectors shall be installed in accordance with the manufacturer's instructions and within the space where the appliance is located. Appliances shall be located as close as practical to the vent or chimney. Connectors shall be as short and straight as possible and installed with a slope of not less than 1/4 inch (6 mm) rise per foot of run. Connectors shall be securely supported and joints shall be fastened with sheet metal screws or rivets. Devices that obstruct the flow of flue gases shall not be installed in a connector unless listed and labeled or approved for such installation.
M1803.3.1 Floor, Ceiling and Wall Penetrations
A chimney connector or vent connector shall not pass through any floor or ceiling. A chimney connector or vent connector shall not pass through a wall or partition unless the connector is listed and labeled for wall pass-through, or is routed through a device listed and labeled for wall pass-through and is installed in accordance with the conditions of its listing and label. Connectors for oil-fired appliances listed and labeled for Type L vents, passing through walls or partitions shall be in accordance with the following:
- Type L vent material for oil appliances shall be installed with not less than listed and labeled clearances to combustible material.
- Single-wall metal pipe shall be guarded by a ventilated metal thimble not less than 4 inches (102 mm) larger in diameter than the vent connector. Not less than 6 inches (152 mm) of clearance shall be maintained between the thimble and combustibles.
M1803.3.2 Length
The horizontal run of an uninsulated connector to a natural draft chimney shall not exceed 75 percent of the height of the vertical portion of the chimney above the connector. The horizontal run of a listed connector to a natural draft chimney shall not exceed 100 percent of the height of the vertical portion of the chimney above the connector.
M1803.3.3 Size
A connector shall not be smaller than the flue collar of the appliance.
Exception: Where installed in accordance with the appliance manufacturer's instructions.
M1803.3.4 Clearance
Connectors shall be installed with clearance to combustibles as set forth in Table M1803.3.4. Reduced clearances to combustible materials shall be in accordance with Table M1306.2 and Figure M1306.1.
| TYPE OF CONNECTOR | MINIMUM CLEARANCE (inches) |
| Single-wall metal pipe connectors: | |
|
Oil and solid-fuel appliances
|
18 |
| 9 | |
| Type L vent piping connectors: | |
|
Oil and solid-fuel appliances
|
9 |
| 3b | |
For SI: 1 inch = 25.4 mm.
- These minimum clearances apply to unlisted single-wall chimney and vent connectors. Reduction of required clearances is permitted as in Table M1306.2.
- Where listed Type L vent piping is used, the clearance shall be in accordance with the vent listing.
M1803.3.5 Access
The entire length of a connector shall allow access for inspection, cleaning and replacement.
M1803.4 Connection to Fireplace Flue
Connection of appliances to chimney flues serving fireplaces shall comply with Sections M1803.4.1 through M1803.4.4.
M1803.4.1 Closure and Accessibility
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.
M1803.4.2 Connection to Factory-Built Fireplace Flue
A different appliance shall not be connected to a flue serving a factory-built fireplace unless the appliance is specifically listed for such an installation. The connection shall be made in compliance with the appliance manufacturer's instructions.
M1803.4.3 Connection to Masonry Fireplace Flue
A connector shall extend from the appliance to the flue serving a masonry fireplace to convey the flue gases 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.
M1803.4.4 Size of Flue
The size of the fireplace flue shall be in accordance with Section M1805.3.1.
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