Results 1 to 14 of 14
  1. #1
    Join Date
    Sep 2008
    Location
    so so, California
    Posts
    1,769

    Default Clarification on vent termination

    M1804.2.3 Natural draft appliances.
    Vents for natural
    draft

    appliances shall terminate at least 5 feet (1524 mm)
    above the highest connected
    appliance outlet,

    I also saw somewhere in the IRC that the B vent must extend a minimum of 1 foot above a sloped roof.

    My question is: What if a waterheater is located on a verticle wall 10 feet high. Is the vent to extend 5 feet or 11 feet?
    Thank you.



    Similar Threads:
    Inspection Referral
    The MAZZA INSPECTION GROUP
    www.mazzainspections.com
    Level III Thermo-picture-taker-er...er

  2. #2
    Join Date
    Nov 2009
    Location
    St Paul, MN
    Posts
    1,628

    Default Re: Clarification on vent termination

    Depends on how tall the water heater is.

    MinnesotaHomeInspectors.com
    Minnesota Home Inspectors LLC
    ASHI #242887 mnradontesting.com

  3. #3
    Join Date
    Mar 2007
    Location
    Santa Rosa, CA
    Posts
    2,481

    Default Re: Clarification on vent termination

    Quote Originally Posted by Marc M View Post
    M1804.2.3 Natural draft appliances.
    Vents for natural
    draft

    appliances shall terminate at least 5 feet (1524 mm)
    above the highest connected
    appliance outlet,

    I also saw somewhere in the IRC that the B vent must extend a minimum of 1 foot above a sloped roof. My question is: What if a waterheater is located on a verticle wall 10 feet high. Is the vent to extend 5 feet or 11 feet?


    Not sure where you are getting the 11 feet. Seems to me that the vent should be a minimum of 5 feet, as long as it extends above the roof. So, if your hypothetical water heater was located in the attic, then 5 feet would be it.

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

  4. #4
    Join Date
    Nov 2009
    Location
    St Paul, MN
    Posts
    1,628

    Default Re: Clarification on vent termination

    Quote Originally Posted by Gunnar Alquist View Post
    [/left]

    Not sure where you are getting the 11 feet. Seems to me that the vent should be a minimum of 5 feet, as long as it extends above the roof. So, if your hypothetical water heater was located in the attic, then 5 feet would be it.

    Marc was thinking floor to ceiling height was 10 feet plus 1 foot above the roof would give an 11 foot vent.

    But the vent connection of the water heater is not at the floor. Typically about 5 feet above the floor which would give a 6 foot long vent. Six feet is ok since 6 feet is "at least 5 feet (1524 mm)
    above the highest connected
    appliance outlet".

    MinnesotaHomeInspectors.com
    Minnesota Home Inspectors LLC
    ASHI #242887 mnradontesting.com

  5. #5
    Join Date
    Jul 2008
    Location
    Snowbird (this means I'm retired and migrate between locations), FL/MI
    Posts
    4,086

    Default Re: Clarification on vent termination

    Is the b-vent connected directly to the appliance or draft hood probably not.

    You have a vent connector likely SW then at least a 12" vertical rise before any offset then the bvent.

    What's your roof material and pitch or slope you'll have to exceed the highest surface in a radius area by a distance certain and note any nearby projections, walls, other which affect the exhaust/draft.

    Is California using the IRC Mechanical chapters now?

    You might find NFPA 211 helpful its the AGA/ANSI standard that the manufacturer's of the gas fired water heaters refer to most often in their instructions.


  6. #6
    Terry Sandmeier's Avatar
    Terry Sandmeier Guest

    Default Re: Clarification on vent termination

    Marc,

    For a gas fired appliance, terminations of B and BW vent need to terminate 1' above roof with a roof pitch up to 6/12. If the vent is closer than 8' to a vertical wall then the vent termination must terminate 2' above roof edge. So the vent at your water heater must extend to 12'.


  7. #7
    Join Date
    Mar 2007
    Location
    Santa Rosa, CA
    Posts
    2,481

    Default Re: Clarification on vent termination

    Ohhh... I get it. I guess I am a little slow today (just today?)

    The termination would need to be above the roof. I seem to recall that a B-vent within 8 feet of a vertical wall must be 2 feet above.

    2006 IRC: 2427.6.4
    2006 UMC: 806.6.2

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

  8. #8
    Join Date
    Mar 2007
    Location
    Santa Rosa, CA
    Posts
    2,481

    Default Re: Clarification on vent termination

    Oh, geeze... too slow on the draw again. But at least, I supplied the sections.

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

  9. #9
    Join Date
    Mar 2007
    Location
    Santa Rosa, CA
    Posts
    2,481

    Default Re: Clarification on vent termination

    Quote Originally Posted by H.G. Watson, Sr. View Post
    Is California using the IRC Mechanical chapters now?
    No, of course not. That would be too easy. We have our own special code that only California gets to use. I think it is based on the IMC.

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

  10. #10
    Join Date
    Sep 2008
    Location
    so so, California
    Posts
    1,769

    Default Re: Clarification on vent termination

    Quote Originally Posted by Ken Rowe View Post
    Marc was thinking floor to ceiling height was 10 feet plus 1 foot above the roof would give an 11 foot vent.

    But the vent connection of the water heater is not at the floor. Typically about 5 feet above the floor which would give a 6 foot long vent. Six feet is ok since 6 feet is "at least 5 feet (1524 mm)
    above the highest connected appliance outlet".
    Thanks Ken... Man, these guys are rough.

    Last edited by Marc M; 12-16-2009 at 11:45 PM.
    The MAZZA INSPECTION GROUP
    www.mazzainspections.com
    Level III Thermo-picture-taker-er...er

  11. #11
    Join Date
    Sep 2008
    Location
    so so, California
    Posts
    1,769

    Default Re: Clarification on vent termination

    Quote Originally Posted by Gunnar Alquist View Post
    Ohhh... I get it. I guess I am a little slow today (just today?)

    The termination would need to be above the roof. I seem to recall that a B-vent within 8 feet of a vertical wall must be 2 feet above.

    2006 IRC: 2427.6.4
    2006 UMC: 806.6.2
    Gunner, can you past the UMC section, I have the 2427. Did you see the table after the 2427, how it shows the different termination heights above the roof line depending on the pitch? Interresting...

    The MAZZA INSPECTION GROUP
    www.mazzainspections.com
    Level III Thermo-picture-taker-er...er

  12. #12
    Join Date
    Jul 2008
    Location
    Snowbird (this means I'm retired and migrate between locations), FL/MI
    Posts
    4,086

    Default Re: Clarification on vent termination

    Oops NFPA 54 - call it a sr. moment.


  13. #13
    Join Date
    Mar 2007
    Location
    Santa Rosa, CA
    Posts
    2,481

    Default Re: Clarification on vent termination

    Quote Originally Posted by Marc M View Post
    Gunner, can you past the UMC section, I have the 2427. Did you see the table after the 2427, how it shows the different termination heights above the roof line depending on the pitch? Interresting...
    Actually, I had not noticed that. Thanks.

    Sorry, typed the UMC section number incorrectly. Presumably, they still require the minimum height above the roof noted in the tables that you mentioned.

    802.6.2.3 A gas vent extending through an
    exterior wall shall not terminate adjacent to
    the wall or below eaves or parapets, except
    as provided in Sections 802.2.5 and 802.3.4.

    802.2.5 Direct-Vent Equipment. Listed direct vent
    gas utilization equipment shall be
    considered properly vented where installed in
    accordance with the terms of its listing, the
    manufacturers' instructions, and Section 802.8.3.

    802.3.4 Mechanical Draft Systems.

    802.3.4.1 Mechanical draft systems shall be
    listed and shall be installed in accordance
    with the terms of their listing and both the
    appliance and the mechanical draft system
    manufacturers' instructions. [NFPA 54:12.4.3.1]

    802.3.4.2 Gas utilization equipment requiring
    venting shall be permitted to be vented by
    means of mechanical draft systems of either
    forced or induced draft design. [NFPA
    54:12.4.3.2]
    Exception: Incinerators.

    802.3.4.3 Forced draft systems and all
    portions of induced draft systems under
    positive pressure during operation shall be
    112

    designed and installed so as to prevent
    leakage of flue or vent gases into a building.
    [NFPA 54:12.4.3.3]

    802.3.4.4 Vent connectors serving equipment
    vented by natural draft shall not be connected
    into any portion of mechanical draft systems
    operating under positive pressure. [NFPA
    54:12.4.3.4]

    802.3.4.5 Where a mechanical draft system
    is employed, provision shall be made to
    prevent the flow of gas to the main burners
    when the draft system is not performing so
    as to satisfy the operating requirements of
    the equipment for safe performance. [NFPA
    54:12.4.3.5]

    802.3.4.6 The exit terminals of mechanical
    draft systems shall be not less than seven (7)
    feet (2.1 m) above grade where located
    adjacent to public walkways and shall be
    located as specified in Sections 802.8.1 and
    802.8.2. [NFPA 54:12.4.3.6]

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

  14. #14
    Join Date
    Sep 2008
    Location
    so so, California
    Posts
    1,769

    Default Re: Clarification on vent termination

    Wow...thanks

    The MAZZA INSPECTION GROUP
    www.mazzainspections.com
    Level III Thermo-picture-taker-er...er

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •