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  1. #1
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    Default Water Heater Venting

    Help -

    I could have sworn at some point that I read about water heater exhaust venting needing to be secured if it was over 4' in length, but I will be damned if I can find it anywhere.




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  2. #2
    Join Date
    Mar 2007
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    Default Re: Water Heater Venting

    Joe, first a question: How tall is that vent? Does it o up through a second story and attic?

    As I recall, there is a horizontal offset limit based on vertical height of the vent.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  3. #3
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    Default Re: Water Heater Venting

    From the IRC: (bold and underlining are mine)

    - G2426.1 (502.1) General.
    - - Vents, except as provided in Section G2427.7, shall be listed and labeled. Type B and BW vents shall be tested in accordance with UL 441. Type L vents shall be tested in accordance with UL 641. Vents for Category II and III appliances shall be tested in accordance with UL 1738. Plastic vents for Category IV appliances shall not be required to be listed and labeled where such vents are as specified by the appliance manufacturer and are installed in accordance with the appliance manufacturer's instructions.


    - G2426.5 (502.5) Installation.
    - - Vent systems shall be sized, installed and terminated in accordance with the vent and appliance manufacturer's installation instructions and Section G2427.


    - G2426.6 (502.6) Support of vents.
    - - All portions of vents shall be adequately supported for the design and weight of the materials employed.


    - G2427.6.9.2 (503.6.10.2) Vent offsets.
    - - Type B and L vents sized in accordance with Item 2 or 3 of Section G2427.6.8.1 shall extend in a generally vertical direction with offsets not exceeding 45 degrees (0.79 rad), except that a vent system having not more than one 60-degree (1.04 rad) offset shall be permitted. Any angle greater than 45 degrees (0.79 rad) from the vertical is considered horizontal. The total horizontal distance of a vent plus the horizontal vent connector serving draft hood-equipped appliances shall be not greater than 75 percent of the vertical height of the vent.


    - G2427.6.10 (503.6.12) Support of gas vents.
    - - Gas vents shall be supported and spaced in accordance with the manufacturer's installation instructions.

    Okay, fine ... however, which manufacturer was that made by?

    Here is one well-known manufacturer's installation instructions: https://duravent.com/wp-content/uplo.../10/L204_W.pdf

    Go to Figure 10 on page 8.

    (NOTE - Added this sentence with edit when correcting the " ' " from the " ? " ) Also on Page 8, right hand column: "8. Tees and Wyes." (see last sentence) "Wall straps every four feet are required."

    Last edited by Jerry Peck; 11-21-2022 at 02:07 PM. Reason: somehow the " ' " turned into " ? " ????
    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  4. #4
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    Default Re: Water Heater Venting

    Unfortunately, California didn't adopt the mechanical portions of the IRC. As a result, we are forced to use the modified version of the UMC.

    This was the only thing that I could find regarding support.


    802.10.8 Support. A vent connector shall be supported for the design and weight of the material employed to maintain clearances and prevent physical damage and separation ofjoints. [NFPA 54:12.11.9]

    Department of Redundancy Department
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  5. #5
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    Default Re: Water Heater Venting

    Gunnar, what Fuel Gas Code has California adopted?

    Also, in the Mechanical Code an what Plumbing Code has California adopted?

    One of them, maybe even all of them, may state to the effect of 'install in accordance with manufacturer's installation instructions', and may also include 'and this code'?

    If they have that in there (the latter part of having to meet "this code" is a given), then the most restrictive of each is applicable. That will get it to "this code" ... "and" ... "manufacturer's installation instructions".

    The manufacturer's installation instructions is frequently where the greater detail comes in.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
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  6. #6
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    Default Re: Water Heater Venting

    The reason I think that "and" may be there is:
    - no requirement for "manufacturer's installation instructions" leaves the code to having to specify everything
    - a requirement for "manufacturer's installation instructions" and no "and" leaves the code out of it and "only" manufacturer's installation instructions" apply.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  7. #7
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    Default Re: Water Heater Venting

    Quote Originally Posted by Jerry Peck View Post
    Gunnar, what Fuel Gas Code has California adopted?
    Also, in the Mechanical Code an what Plumbing Code has California adopted?
    Jerry,

    That is a good question. I wish I knew which fuel gas code. The powers that be decided to only use the building portion of the IRC and continue using modified versions of the UPC, UMC, and NEC. Back in the day, most of us hoped (assumed?) that residential contractors and home inspectors would only have to purchase one book. Boy, weren't we surprised when we found out that the Building Standards Commission decided to keep the status quo?

    At one point, I recall reading that California wanted to keep the relationship with NFPA and IAPMO, so elected to continue with those codes. As a result, it seems reasonable that they would keep using NFPA 54, but for our fire code we are using the IFC rather than NFPA 1, so anybody's guess. I checked the BSC website for the past three cycles and no fuel gas code is listed. When I have a chance, I will ask someone who will know more.

    Quote Originally Posted by Jerry Peck View Post
    One of them, maybe even all of them, may state to the effect of 'install in accordance with manufacturer's installation instructions', and may also include 'and this code'?

    If they have that in there (the latter part of having to meet "this code" is a given), then the most restrictive of each is applicable. That will get it to "this code" ... "and" ... "manufacturer's installation instructions".
    Yes, I know I have seen that statement in at least one code and it probably is in all of them.

    Quote Originally Posted by Jerry Peck View Post
    The manufacturer's installation instructions is frequently where the greater detail comes in.
    The problem that I see with Joe's picture specifically is that the diagonal looks to be a single-walled connector. I don't recall having seen installation instructions for single-wall.

    Department of Redundancy Department
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  8. #8
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    Default Re: Water Heater Venting

    Quote Originally Posted by Gunnar Alquist View Post
    The problem that I see with Joe's picture specifically is that the diagonal looks to be a single-walled connector. I don't recall having seen installation instructions for single-wall.
    My thoughts at first too, then I reasoned that it must be B-vent as single wall would be installed backwards (male end should be into female end in the direction of venting for single wall to keep the venting flow in the single wall vent piping) - and that looks to be female end (at top end of it) over male end ... if that is single wall.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

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