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  1. #1
    Brian E Kelly's Avatar
    Brian E Kelly Guest

    Default Single wall pipe to b-vent vent question

    I have a problem finding the proper code reference for the following venting situation.
    I have a furnace that start off the furnace with single wall pipe then goes to b-vent where it goes thru a wall then back to single wall pipe to the masionary chimney.
    I know it is not proper but as I said I can not find the proper code in either the NYS Building Codes or the NYS Fuel Gas Code. Any help would be appreciated.

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    Certified Master Inspector CMI

  2. #2
    Join Date
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    Default Re: Single wall pipe to b-vent vent question

    No single wall is allowed in concealed locations. Single wall is not allowed outdoors in cold climates. See G2424.7 of the 2003 IRC.

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  3. #3
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    Default Re: Single wall pipe to b-vent vent question

    Brian,

    There is also a wealth of information (largely from Bob Harper) in the archives regarding venting a furnace through a masonry chimney that you might want to peruse.

    Department of Redundancy Department
    http://www.FullCircleInspect.com/

  4. #4
    Brian E Kelly's Avatar
    Brian E Kelly Guest

    Default Re: Single wall pipe to b-vent vent question

    I did forget to mention that all the venting is done inside in a back room that is conditioned.

    Thanks


  5. #5
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    Default Re: Single wall pipe to b-vent vent question

    From the 2006 IRC. (bold is mine)
    - G2427.7 (503.7) Single-wall metal pipe. Single-wall metal pipe vents shall comply with Sections G2427.7.1 through G2427.7.12.
    - - G2427.7.1 (503.7.1) Construction. Single-wall metal pipe shall be constructed of galvanized sheet steel not less than 0.0304 inch (0.7 mm) thick, or other approved, noncombustible, corrosion-resistant material.
    - - G2427.7.2 (503.7.2) Cold climate. Uninsulated single-wall metal pipe shall not be used outdoors for venting appliances in regions where the 99-percent winter design temperature is below 32ºF (0ºC).
    - - G2427.7.3 (503.7.3) Termination. Single-wall metal pipe shall terminate at least 5 feet (1524 mm) in vertical height above the highest connected appliance draft hood outlet or flue collar. Single-wall metal pipe shall extend at least 2 feet (610 mm) above the highest point where it passes through a roof of a building and at least 2 feet (610 mm) higher than any portion of a building within a horizontal distance of 10 feet (3048 mm) (see Figure G2427.6.4). An approved cap or roof assembly shall be attached to the terminus of a single-wall metal pipe (see also Section G2427.7.8, Item 3).
    - - G2427.7.4 (503.7.4) Limitations of use. Single-wall metal pipe shall be used only for runs directly from the space in which the appliance is located through the roof or exterior wall to the outdoor atmosphere.
    - - G2427.7.5 (503.7.5) Roof penetrations. A pipe passing through a roof shall extend without interruption through the roof flashing, roof jack, or roof thimble. Where a single-wall metal pipe passes through a roof constructed of combustible material, a noncombustible, nonventilating thimble shall be used at the point of passage. The thimble shall extend at least 18 inches (457 mm) above and 6 inches (152 mm) below the roof with the annular space open at the bottom and closed only at the top. The thimble shall be sized in accordance with Section G2427.10.15.
    - - G2427.7.6 (503.7.6) Installation. Single-wall metal pipe shall not originate in any unoccupied attic or concealed space and shall not pass through any attic, inside wall, concealed space, or floor. The installation of a single-wall metal pipe through an exterior combustible wall shall comply with Section G2427.10.15. Single-wall metal pipe used for venting an incinerator shall be exposed and readily examinable for its full length and shall have suitable clearances maintained.
    - - G2427.7.7 (503.7.7) Clearances. Minimum clearances from single-wall metal pipe to combustible material shall be in accordance with Table G2427.7.7. The clearance from single-wall metal pipe to combustible material shall be permitted to be reduced where the combustible material is protected as specified for vent connectors in Table G2409.2.
    - - G2427.7.8 (503.7.8) Size of single-wall metal pipe. A venting system constructed of single-wall metal pipe shall be sized in accordance with one of the following methods and the appliance manufacturer’s instructions:
    - - - 1. For a draft-hood-equipped appliance, in accordance with Section G2428.
    - - - 2. For a venting system for a single appliance with a draft hood, the areas of the connector and the pipe each shall be not less than the area of the appliance flue collar or draft hood outlet, whichever is smaller. The vent area shall not be greater than seven times the draft hood outlet area.
    - - - 3. Other approved engineering methods.
    - - G2427.7.9 (503.7.9) Pipe geometry. Any shaped single-wall metal pipe shall be permitted to be used, provided that its equivalent effective area is equal to the effective area of the round pipe for which it is substituted, and provided that the minimum internal dimension of the pipe is not less than 2 inches (51 mm).
    - - G2427.7.10 (503.7.10) Termination capacity. The vent cap or a roof assembly shall have a venting capacity not less than that of the pipe to which it is attached.
    - - G2427.7.11 (503.7.11) Support of single-wall metal pipe.All portions of single-wall metal pipe shall be supported for the design and weight of the material employed.
    - - G2427.7.12 (503.7.12) Marking. Single-wall metal pipe shall comply with the marking provisions of Section G2427.6.11.

    This is what applies to your installation:
    - G2427.7.4 (503.7.4) Limitations of use. Single-wall metal pipe shall be used only for runs directly from the space in which the appliance is located through the roof or exterior wall to the outdoor atmosphere.

    In the installation you describe, the single wall vent *does not* "only runs directly from the space in which the appliance is located" and then "through the roof or exterior wall". It runs through in intervening interior wall and intervening interior space.


    Last edited by Jerry Peck; 12-19-2007 at 05:37 AM.
    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  6. #6
    Brian E Kelly's Avatar
    Brian E Kelly Guest

    Default Re: Single wall pipe to b-vent vent question

    Thank you Jerry, that is exactly what I am looking for.


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