Annoying harmonic tone in water piping

[Gerarddm]

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?

[Paul Pless]

magnetohydrodynamic pump, or caterpillar, will fix your problem

[L.W. Baxter]

i take it your pipes are metal?

install a section of pex just after the water heater.

[AndyG]

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

[David W Pratt]

Turn up the radio?

[RFNK]

i take it your pipes are metal?

install a section of pex just after the water heater.

This

[Gerarddm]

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.

[bluedog225]

Sharkbite is worth every penny.

[L.W. Baxter]

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.

[RFNK]

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.

[Canoeyawl]

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

[Gerarddm]

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.

[bluedog225]

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

[Paul Pless]

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

[RFNK]

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?

[Canoeyawl]

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...

[stromborg]

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.

[Paul Pless]

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

[bluedog225]

How many medium dogs can it hold?

[Gerarddm]

#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.