whistling-humming sound in pipes

paul_21

I have a Hydro Therm gas fired hot water boiler. The system has 3 zone valves with 1 circulator pump.

Last winter I noticed a slight whistling/humming sound coming from the boiler traveling through the pipes when the system called for heat. When all 3 zones were calling from heat I did not here it. When the main floor zone vave called for heat I would hear it. I called my service man last year and he could not identify what was causing it. I recently had another service man come and he identiied the problem as being a fautlty zone valve that controls the main floor.

He replaced the main floor zone valve and the noise stopped for about two weeks. The noise started again yesterday.

Does anyone know what's causing this??? It is quite annoying. I've bleed the system several times so I don't have any air in the system.

Please help!!

Pat Clark

May be pump noise

Sounds like the pump may be oversized causing the noise. Post the make and model of the pump here and that will help. Since it seems to only do it when the one zone is open only you may be overpumped and too much flow is causing the noise.

Pat

Dale

To check

To check the pump idea of the other post if you're lucky you have a valve flange or valve at the pump outler, you can slowly close this when the noise is there and see if it lessens. You may have a pump coupling going if you have a series 100, you can put on a glove and grasp all the parts to see if the sound changes.

Mark J Strawcutter

low flow

I seem to remember reading here that some boilers will emit such a noise when there is insufficient flow thru their heat exchangers. Perhaps yours is one of those.

Mark

Jim Eastman

I, too, had this problem. If the whistling or moaning noise goes away as you cut the gas flow to the boiler when only one zone is open, then it probably is inadequate flow through the exchanger. Installing a differential pressure by-pass valve may help keep the flow at a level sufficient to keep the harmonics from setting up in the boiler.

Jim Eastman
Precision Plumbing
Boulder, CO

paul_21

whistling/humming

I've confirmed that the humming only happens when the main floor zone valve calls for heat. My basement and my second floor can call for heat and you will not hear that noise. If the main floor is calling for heat it humms once of the other zones kicks in, the humming stops.

My circulator pump was replaced about two years ago. The original pump was a red b&g(??) that had to be oiled. The replacement is a taco cartride pump that requires no oiling. The model number is 007-f5.

hp: 1/25
amps: .71
rpm 3250

I only had two zones when I had that old pump. I added two zones onto the system back in 1998 (the main floor and basement) and I never heard the noise. The pump was the original and it went. The serviceman replaced it with the taco. Now that I think about it, I added the 3rd zone around the time the new pump was put in. Is it possible it's the pump?? Do I need that big red one that you have to oil??

please give me your thoughts.

Mark J Strawcutter

007

another application of the "universal" 007 circulator.

You need to find out what the flow requirements of your boiler are, and compute the head loss of each zone. Then see if there is a circulator that can handle things with any combination of zones calling for heat.

re-piping primary/secondary would be one way to go, and as someone else said a differential pressure bypass valve may be desirable even with a different circulator.

If I understand correctly, things worked fine with zoning as you have it now but with a B&G 100 circulator? If so, you may just want to swap out the 007 for a new 100.

Mark

JohnNY

I've encountered that

...on those low water content boilers, like the Teledyne.
But never with a cast-iron boiler, which I believe the Hyro-Therm is.

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paul_21

RE PIPING

Why repipe the primary and secondary??? What would that do??

Where do I go to check the flow rate of the boiler??

Why would the B&G pump not produce the noise. Is it more powerful than the Taco??

Where do you install a flow differential?

Mark J Strawcutter

>Why repipe the primary and secondary??? What would that do??

Not repipe _the_ primary and secondary, as with only one circulator I don't think you're currently piped that way. Repiping _as_ primary/secondary would allow you to properly size one circulator to meet the needs of the boiler and another to meet the needs of the system.

>Where do I go to check the flow rate of the boiler??

From the manufacturer's documentation for the boiler.

>Why would the B&G pump not produce the noise. Is it more powerful than the Taco??

Depends where on each circulator's performance curve you'd be operating.

>Where do you install a flow differential?

differential pressure bypass goes between supply and return.

You might be interested in reading "pumping away" and "primary/secondary pumping made easy" from books and more on this site.

Or, give "find a professional" here a try.

Lastly - could also be a problem with the zone valve on the zone that causes the noise. May sound like it's coming from the boiler, but noises are sometimes deceiving.

Mark