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  1. #1
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    Mar 2011
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    Lombard, Illinois
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    Default Gas water heater venting

    What is the standard height between the vent pipe collar and the top of the unit. The picture depicts my own unit with a 1.1/2 space. I've been seeing unit with 2-3" spacing. The larger spacing may not be venting the C0 properly. Any help/suggestion would be great.

    Thank you in advance for any help.

    Happy New Year to all. Please stay safe

    Fidel

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  2. #2
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    Mar 2007
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    Default Re: Gas water heater venting

    Since water heaters come with the vent hood, the correct vent hood is the one that comes with the water heater.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  3. #3
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    Default Re: Gas water heater venting

    Quote Originally Posted by Rick Cantrell View Post
    Since water heaters come with the vent hood, the correct vent hood is the one that comes with the water heater.
    Thank you soooo much Rick

    Fidel F. Gonzales
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  4. #4
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    Cool Re: Gas water heater venting

    I'd worry about the lack of proper vent rise and if that 3" doesn't increase to 4" to get some lift out of it.


    Just understand draft hoods were designed to spill fumes. unfortunately, they work.

    Keep the fire in the fireplace.

  5. #5
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    Mar 2007
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    Healdsburg, CA
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    Default Re: Gas water heater venting

    I'd be more worried about the lack of proper rise on the vent connector.

    Jerry McCarthy
    Building Code/ Construction Consultant

  6. #6
    Join Date
    Jul 2010
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    Burbank, CA
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    Default Re: Gas water heater venting

    As Jerry and Bob said, you need rise, 1/4" per foot in the connector. The bottom line is, does it vent the appliance without spillage? When I can get to them without a ladder, I'll run the WH for at least 10 minutes and then check for spillage with a mirror.

    Gary DeWitt
    CREIA Certified Inspector
    burbankhomeinspections.com

  7. #7
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    Cool Re: Gas water heater venting

    mirrors only show if moisture is spilling from that side of the draft hood. If there is no fogging of a mirror, that does not prove the unit is venting properly. You can have a clean mirror with no flue gases making it into the flue. Draft hoods de-couple the vent from the appliance and allow spillage by design. Unfortunately, they work.

    Keep the fire in the fireplace.

  8. #8
    Join Date
    Mar 2007
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    Ormond Beach, Florida
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    26,252

    Default Re: Gas water heater venting

    Quote Originally Posted by Gary DeWitt View Post
    As Jerry and Bob said, you need rise, 1/4" per foot in the connector.
    And a minimum 1 foot rise before the first elbow.

    Looks like single wall vent, where does it go or what does it go into?

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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  9. #9
    Join Date
    Jun 2010
    Location
    Rochester, NY
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    Default Re: Gas water heater venting

    Natural draft water heaters should be against the law.

    As some have indicated, you may be worrying about the wrong side of this problem. Flue pipe pitch, and chimney lining would worry me.

    If you don't have a CO detector or manometer there are some important tests you can not perform. You can at least test spillage at worst case. Turn on all venting devices including dryer, kitchen and bath fans, then fire water heater.

    If you burn your hands putting them near the draft hood, the appliance is not overcoming backdraft of chimney. If this persists for more than 60 seconds there is a big problem. A properly drafting water heater, you will feel cool basement air pulling through your hands toward the draft hood, not hot exhaust spilling out.

    Often a poorly drafting water heater will have signs of spillage. Scorch marks on tank top, melted pipe insulation, etc.

    Last edited by ted kidd; 01-01-2012 at 08:23 PM.

  10. #10
    Join Date
    Feb 2011
    Location
    Michigan
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    9

    Default Re: Gas water heater venting

    The drafthood is designed for that particular.

    Unless, they switched drafthoods.

    You should be checking for proper draft at the drafthood anyway.

    No matter the configuration, (unless it's vented thru pvc), turn on the furnace, let it run for about 5 min's. Then turn-up the water heater.
    Now, place a lite lighter just at the edge (about 1" away) of the drafthood (not inside). If it's drafting OK, the flame will stay lite, and be draw towards the drafthood. If it's blown-out, that means you have vent gas spillage, or a draft problem. The flame needs air/oxygen, there's none in vent gases.


  11. #11
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    Default Re: Gas water heater venting

    Sorry Cornish but a flame drawing inwards only indicates room air being entrained up the vent. There are cases where this can happen with venting failure. The only way to tell for sure if it is venting properly is by combustion analysis and measuring draft pressures above and below the draft hood along with testing along the floor for CO and decreased O2. Its called a Door Curtain Effect. May take more than 5 min. to setup. Cause by high draft.

    Keep the fire in the fireplace.

  12. #12
    Join Date
    Mar 2007
    Location
    Spring City/Surrounding Philadelphia area
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    Default Re: Gas water heater venting

    The way some houses are built around here, there's almost no way to accomplish 1' of vertical rise on some water heater installs before the 1st elbow.

    "It takes a big man to cry. It takes an even bigger man to laugh at that man". - Jack Handey

  13. #13
    Join Date
    Jun 2010
    Location
    Rochester, NY
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    31

    Default Re: Gas water heater venting

    Quote Originally Posted by Cornish Home Inspections View Post

    No matter the configuration, (unless it's vented thru pvc), turn on the furnace, let it run for about 5 min's. Then turn-up the water heater.
    Create a powerful draft, then check for draft? Hmmm.

    Wouldn't you want to check a COLD chimney rather than a HOT chimney? BPI says start with smallest appliance first...


  14. #14
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    Mar 2007
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    Near Philly, Pa.
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    Default Re: Gas water heater venting

    Nick. that's true when the chimney breaching or B-vent connection is already 6" below the combustible ceiling above. However, where there is a masonry chimney with the breaching several feet below the ceiling, you can open the basement wall and relocate the breaching where it should be. Better yet, install a listed liner to do it properly. With a 40 K WH, the vent connector should be increased to 4" if less than 3ft of vent rise.

    Keep the fire in the fireplace.

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