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Lochinvar knight boiler noise

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Dave_132
Dave_132 Member Posts: 64
in THE MAIN WALL
I thought that i would share a phenomenon that occurred last week on one of my jobs.I started a KBN105 and as it ramped up it began to howl. The venting, combustion,gas pressure, flow and all other aspects of the installation were correct.What i was experiencing is what is known as thermo acoustic vibration. This would occur as the unit established ignition and then ramped up. At about 50% firing rate the noise would go away. I contacted Lochinvar and they were already aware of this problem. Although rare, they supplied me with a stiffening bracket which extends left to right across the header and is drawn tight. This tension eliminated the problem.

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  • TParge
    TParge Member Posts: 4
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    System Vibration

    I've got a similar and perhaps the same issue.  .  .

    I'm getting a very loud vibration noise from my  Lochinvar Knight 150.  It happens upon start-up, and has gotten worse; starting at lasting about 30 seconds, and now lasting about 90 seconds before it stops.

    I just recently cleaned it after being told by the Plumbing guys that was the reason for the vibrations.  Not so.  No change. (But a clean burner and box) 



    Is the 'stiffening bracket' placed in the heating unit itself? 

    Tom
  • icesailor
    icesailor Member Posts: 7,265
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    Noises:

    Have you or anyone else used a digital combustion analyzer on the exhaust and a digital manometer on the gas control?

    When one part of "The Triad", air, fuel and heat is off, things go south. On start up, it can only be the first two, air and fuel because it takes them to make the third.
  • Zman
    Zman Member Posts: 7,569
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    Absolutely a combustion issue

    With the firetube heat exchanger the howl you are describing is a combustion issue.

    It is likely running to lean, a combustion analysis will resolve the noise.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Gordan
    Gordan Member Posts: 891
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    KBN is the Giannonni

    WHN is firetube.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
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    howling

    It is a combustion problem.

    How long is your vent pipe??

    I have found in the past that if your vent pipeing is too short or doesn't cause enough back pressure on the boiler it can cause this howling.

    I picked up a new customer two years ago that someone installed a 4 inch vent where a 3 inch would have worked fine.

    I couldn't stop the howling untill I installed a 4 to 2 tapered coupling and a 12 inch stinger on the end of the vent pipe.

    The howling stoped and I was able to dial the boiler in.
  • TParge
    TParge Member Posts: 4
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    Lochinvar bad vibration

    My vent tube is about 5', with 8 inches coming out of boiler, 90 degree elbow, 45 inches up, 90 degree elbow, then 8 inches out to outside surface of the wall. I am using 4" pipe for both air and vent. I would like to extend the pipe out from the house, perhaps this is my chance. (But I live in Alaska, and the condensate may freeze and create a blockage.)



    This is a new event, the howling, so I seems like there must have been some change. I installed this boiler about 3 years ago.
  • TParge
    TParge Member Posts: 4
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    Heat Exchanger vibrating big time

    Never had the analyzer or the manometer used on my machine. I did put my hand in there and feel that it was the heat exchanger that was vibrating so. As that is where the combustion takes place, I can imagine that it could be the issue. How, then, do I fix the combustion problem, and will changing the vent in some way help?
  • TParge
    TParge Member Posts: 4
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    KB-150

    Sounds like I need a professional to come in and adjust the combustion? I'm the home owner, I installed this mamma-jamma myself; It is too complex for me to adjust? Does it require meters that I don't have. . .
  • Zman
    Zman Member Posts: 7,569
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    Combustion

    You need a combustion analyzer.I would look for a company that regularly works on these. I know many companies that install without tuning. You do not want to use them.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
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    BINGO

    Too short of a vent pipe with TOO big of a pipe.

    change it to 3 inch and OR install a restrictor at the vent pipe termination.

    Try a 4 to 2 reducing coupling and 6 inches of 2 inch PVC.
  • icesailor
    icesailor Member Posts: 7,265
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    Noises:

    A 4" PVC coupling and a 4"X3" or 2" Reducing Bushing is a fine way to test out the theory. Or, you can clamp the bushing on with a 4" No-Hub coupling. No-Hub couplings are fine tools in the repair and experiment kit. I don't leave home without them.

    Did you test the gas pressure at the valve and outlet of the valve and do a combustion analysis yet? Some are waiting to hear.
  • Dave_132
    Dave_132 Member Posts: 64
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    Stiffening bracket

    The bracket fits inside the cabinet and tightens across the top of the heat exchanger. Give tech service a call at Lochinvar 1-800-722-2101 and they should be able to help you with this

    There was an error rendering this rich post.

  • Dave_132
    Dave_132 Member Posts: 64
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    Stiffening bracket

    The bracket fits inside the cabinet and tightens across the top of the heat exchanger. Give tech service a call at Lochinvar 1-800-722-2101 and they should be able to help you with this

    There was an error rendering this rich post.

  • Dave_132
    Dave_132 Member Posts: 64
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    Stiffening bracket

    The bracket fits inside the cabinet and tightens across the top of the heat exchanger. Give tech service a call at Lochinvar 1-800-722-2101 and they should be able to help you with this

    There was an error rendering this rich post.

  • Dave_132
    Dave_132 Member Posts: 64
    Options
    Stiffening bracket

    The bracket fits inside the cabinet and tightens across the top of the heat exchanger. Give tech service a call at Lochinvar 1-800-722-2101 and they should be able to help you with this

    There was an error rendering this rich post.

This discussion has been closed.

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