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Thread: Annoying harmonic tone in water piping

  1. #1
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    Default Annoying harmonic tone in water piping

    We had a hot water recirculating system installed since it was taking too long for the water to heat up at the extreme ends of the house. The pump for it is mounted on top of the water heater.

    The system works fine, but it has an annoying harmonic hum that is irritatiing me. The installer pumber says nothing much can be done about it. When I put a 3lb lead diver's weight on top of the Taco pump, it helps kill ancillary vibration noise from the pump, but the piping itself is still humming. When I hand squeeze the pipe insulation just before the pump, it does knock the hum down a touch.

    Query: what can I do about this? Clamp a weight the pipe to change the harmonic frequency? Or?
    Last edited by Gerarddm; 09-19-2022 at 05:33 PM.
    Gerard>
    Albuquerque, NM

    Next election, vote against EVERY Republican, for EVERY office, at EVERY level. Be patriotic, save the country.

  2. #2
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    Default Re: Annoying harmonic tone in water piping

    magnetohydrodynamic pump, or caterpillar, will fix your problem
    Simpler is better, except when complicated looks really cool.

  3. #3
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    Default Re: Annoying harmonic tone in water piping

    i take it your pipes are metal?

    install a section of pex just after the water heater.

  4. #4
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    Default Re: Annoying harmonic tone in water piping

    I had a twenty-year-old fan on my water boiler that, late last year, started to whine when running, and then sound like an RB211 winding down when finished.

    I bought a 'reconditioned' replacement (70 rather than new at 200), and swapped it out. It required the strength of Conan with five-year-old hands to access and extract the beast.

    'New' fan's bearings lasted about 84 seconds. It screamed within two minutes.

    So I squooshed the old fan's wobbly bearings with WD40 and some copper grease, replaced it, and here I am. Ten months on, and continuing silence.

    Sorry that that's no help for your situation, but I found it insightful.

    BTW, the suggested PEX link is the answer, I think. Disconnect the source from the harmonic generator.

    Andy
    "In case of fire ring Fellside 75..."

  5. #5
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    Default Re: Annoying harmonic tone in water piping

    Turn up the radio?

  6. #6
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    Default Re: Annoying harmonic tone in water piping

    Quote Originally Posted by L.W. Baxter View Post
    i take it your pipes are metal?

    install a section of pex just after the water heater.
    This
    Rick

    Lean and nosey like a ferret

  7. #7
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    Default Re: Annoying harmonic tone in water piping

    Yes, system pipe is copper. The interim pex is an idea, hmmmm.

    The Taco pump is mounted to the top of the water heater, then the metal flex conduit pipe flexs up a bit then back down to horizontally penetrate the wall.

    Paul, remember Dallas tracked Red October.
    Gerard>
    Albuquerque, NM

    Next election, vote against EVERY Republican, for EVERY office, at EVERY level. Be patriotic, save the country.

  8. #8
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    Default Re: Annoying harmonic tone in water piping

    Sharkbite is worth every penny.

  9. #9
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    Default Re: Annoying harmonic tone in water piping

    might have to repipe the whole house. and then what if that doesn't work?

    we had a vibration, intermittent, source never identified (likely heavy machinery of some sort at a distant location) through our black iron drains. noise was focused at the bathroom sink drain. we could even cut the noise temporarily by simply running the tap. this spring i replaced the bathroom drains with abs and we have not heard the noise since.

  10. #10
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    Default Re: Annoying harmonic tone in water piping

    We've had noises that sound like a low flute caused by valves. But the low harmonic noise is much harder to trace. That's why I think putting in a section of flexible pipe, pretty much anywhere, but preferably close to the apparent source, is a really good idea. I'll be very surprised if it doesn't work.
    Rick

    Lean and nosey like a ferret

  11. #11
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    Default Re: Annoying harmonic tone in water piping

    Quote Originally Posted by L.W. Baxter View Post
    might have to repipe the whole house. and then what if that doesn't work?

    we had a vibration, intermittent, source never identified (likely heavy machinery of some sort at a distant location) through our black iron drains. noise was focused at the bathroom sink drain. we could even cut the noise temporarily by simply running the tap. this spring i replaced the bathroom drains with abs and we have not heard the noise since.
    When I was quite young my dad (and I) built a crystal radio that we hooked up to the bathroom sink drain...
    That would never work with abs

  12. #12
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    Default Re: Annoying harmonic tone in water piping

    A plumber tells me pex pipe within 18" of the hot water tank is verboten by code, and that is the only access to system piping I've got without ripping into sheetrock, so pex is out as a solution.

    For now the lead 3 lb. diver's weight placed on top of the Taco pump and a Vise-Grip gently squeezing directly on the flex conduit is about all I can do to change the harmonic frequency. It helps some.
    Gerard>
    Albuquerque, NM

    Next election, vote against EVERY Republican, for EVERY office, at EVERY level. Be patriotic, save the country.

  13. #13
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    Default Re: Annoying harmonic tone in water piping

    Shark bite might help break the connection. If it is allowed.

  14. #14
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    Default Re: Annoying harmonic tone in water piping

    Quote Originally Posted by Gerarddm View Post
    A plumber tells me pex pipe within 18" of the hot water tank is verboten by code, and that is the only access to system piping I've got without ripping into sheetrock, so pex is out as a solution.

    For now the lead 3 lb. diver's weight placed on top of the Taco pump and a Vise-Grip gently squeezing directly on the flex conduit is about all I can do to change the harmonic frequency. It helps some.
    can you purge air from your system

    my kennel has an extensive hot water system - we use 3500 gallons of hot water per day - with very large hammer arrestors

    still harmonics would build up in the system from time to time - doing an air purge would help
    Simpler is better, except when complicated looks really cool.

  15. #15
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    Default Re: Annoying harmonic tone in water piping

    Quote Originally Posted by Gerarddm View Post
    A plumber tells me pex pipe within 18" of the hot water tank is verboten by code, and that is the only access to system piping I've got without ripping into sheetrock, so pex is out as a solution.

    For now the lead 3 lb. diver's weight placed on top of the Taco pump and a Vise-Grip gently squeezing directly on the flex conduit is about all I can do to change the harmonic frequency. It helps some.
    Is that the plumber's solution?
    Rick

    Lean and nosey like a ferret

  16. #16
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    Default Re: Annoying harmonic tone in water piping

    Quote Originally Posted by Paul Pless View Post
    can you purge air from your system

    my kennel has an extensive hot water system - we use 3500 gallons of hot water per day - with very large hammer arrestors

    still harmonics would build up in the system from time to time - doing an air purge would help
    Usually purging excess water is what is required. It is the cushion of air that allows an arrestor to work...

  17. #17
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    Default Re: Annoying harmonic tone in water piping

    Quote Originally Posted by Gerarddm View Post
    A plumber tells me pex pipe within 18" of the hot water tank is verboten by code, and that is the only access to system piping I've got without ripping into sheetrock, so pex is out as a solution.

    For now the lead 3 lb. diver's weight placed on top of the Taco pump and a Vise-Grip gently squeezing directly on the flex conduit is about all I can do to change the harmonic frequency. It helps some.
    Our tank, inspected 14 months ago has PEX leading to 24" of copper pipe into the tank and nothing but PEX coming out on the hot side. Local code? Get a second opinion? The Grundfos pump running my system is virtually silent.
    Steve

    If you would have a good boat, be a good guy when you build her - honest, careful, patient, strong.
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  18. #18
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    Default Re: Annoying harmonic tone in water piping

    Quote Originally Posted by Canoeyawl View Post
    Usually purging excess water is what is required. It is the cushion of air that allows an arrestor to work...
    yes, but if there is an air bubble at the top of a hot water tank or inside a long run of large diameter pipe or inside an extremely large dishwasher* then the harmonics can be crazy


    * our dishwasher is large enough to wash two large dog crates inside of at a time
    Last edited by Paul Pless; 09-22-2022 at 09:44 PM.
    Simpler is better, except when complicated looks really cool.

  19. #19
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    Default Re: Annoying harmonic tone in water piping

    How many medium dogs can it hold?

  20. #20
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    Default Re: Annoying harmonic tone in water piping

    #15: No, my solution until I can think of something else.

    Changing the Taco for a Grundfos might be an idea. We used Grundfos exclusively with solar hot water systems decades ago, never an issue with them.
    Gerard>
    Albuquerque, NM

    Next election, vote against EVERY Republican, for EVERY office, at EVERY level. Be patriotic, save the country.

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