Difficult problem -- crackling noise in pipes

Jeff Elston

I would bet on a piece of debris in the pipe

Came to mind when I read title on main page

About the pump sucking and not pushing what do those pressure gauges read when your crackin away

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Jeff Bannon

Difficult problem -- crackling noise in pipes

I am experiencing a loud sort of crackling noise in one area of my copper single loop pipe zone which brings heat to my basement. This zone was recently added, as the basement was not heated before. I have a two pipe system feeding the rest of the house (first and second floors, zone 1). This noise is not expansion noise or air noise (all air vents have been bled). The noise is only in one are of the main loop -- it is not in any of the radiators.

This noise gets very loud, waking us up at night, and only begins once the water rises in temperature -- I'm not sure exactly which temperature, but the noises probably begin at around 140 degrees or so.

Furthermore, and this is important, the noise ONLY arises when the circulator for that zone is turned on. As soon as the circulator is powered off, the noise stops almost immediately.

I don't have any noise problems with any other part of the entire system.

Do you think the problems I am experiencing could be due to the location of the Circulator in that zone? From the fact that the circulator in this zone is 'sucking' rather than 'pushing' the water through the zone, and is located near the end of the zone (rather than near the beginning), this could be altering the pressure signficantly to the point of perhaps creating so-called "micro-jets" of water boiling. The only confusing thing is the location of the noise -- it is no where near the circulator.

Do you think that if I move the circulator to the beginning of the zone (so that it's 'pushing' rather than 'pulling' the water), that this will solve the noise problems? I guess I can always try it but I don't want to move it for nothing!

Does anyone have any other ideas?

Thank you so much for your help.

Mark Hunt

Question


How are the pipes supported?

Do the pipes go through joists?

Mark H

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frank_25

things that go bang in the night

IF ya got baseboard you should look for improperly supported fin-tube within the enclosure. There are usually plastic saddles that rest on the baseboard clips that hold the covers in place. [The fin tube rests on the plastic] On any system Also check every tube penetration thru walls, floors, ceilings, etc. If the tube hole is tight, or the tube is touching something such as a metal stud, wood framing, etc. you will hear sound of the "give" of expansion. I suggest you get down on your knees, remove the covers and look for a pinch-point. Look at all the tube in that loop. If that doesn't prove out, there may be debris [as mentioned previously] in the tube that won't pass by a fitting. Perhaps an excessive amount of solder was used and it puddled inside the tube. Now the water is pushing it around and it's letting you know about it. If that's it, then you'll have to remove a section or two or three and flush out the tube. Whatever, good luck. bwdik,ijap

[Deleted User]

Pumps suck....

Short answer. Move the pumps so that they both pump away from the boiler and expansion tank and your problems WILL go away, or my name is not Orville Reddenbocker.

What you are hearing is steam cavitation. Sounds like mini fire crackers going of INSIDE the pipe.

Orv

ht in pa_2

This reminds me of a noise once that about drove the home owner crazy. It turned out to be a piece of solder that had become lodged in the empeller of the circulator. It's an easy thing to fix if you have isolation valves on either side of the circulator.

brucewo1b

I'll try moving the location of the pump

Thanks for all of the suggestions. I have ruled out the possibility of water hammer, plus you can tell by listening that it's a different noise. Like one author said here, it sounds more like fire crackers going off in the pipes. I thought it might be extra solder originally, so I drained the system twice, but that didn't fix it. Also, the noise only begins once the water temperature begins to rise, lets say around 120 degrees or so -- if it was solder than I would think the noise should appear even when the water is cold.

From all of the research I have done, I am going to try moving the location of the pump to AFTER the expansion tank.

I personally emailed John Siegenthaler of hydronicpros.com, and he also agreed that it's mostly likely cavitation and moving the pump will likely solve the problem.

Note the pressure of the existing two gauges is positive (at least 15psi once heating up), but I don't know what the pressure is at the actual location of the noises. Perhaps the pressure over there is negative, which is causing the cavitation. Let's see what happens from moving the circulator. I hope it works! And I'll let you all know. I heard putting the circulator after the expansion tank is almost miraculous and solves many issues. We'll see!

subcooler

What is the make & size of circulator 3?

[Deleted User]

Ah garontee ya....

ME

Jeff Bannon

Difficult problem -- crackling noise -- pump size?

The size of the existing pump is an Armstrong Astro 50 pump. I was originally going to move the pump location, but then I actually shut off the expansion tank valve (i.e., eliminate expansion tank from the system). But my problem still remains -- fairly consistent crackling noises in the pipes!

Could it be my pump is too powerful and it causes the noises when turned on? But there is no noise while the water is cold. If the cause of the noises was an over-sized pump, wouldn't the noise exist regardless of water temperature?

I don't know what to do. Any suggestions on what I could try to eliminate the noise?

rob_26

zone valves

i had the same problem and we moved the zone valves to the return.(pump was on the supply) every time the circulator would stop this banging chilling noise would be created throughout the house

Anna Conda

The boiling temperature of water is directly related to the pressure that the water is under. When people say "water boils at 212F", what is meant is, water boils at 212F at sea level atmospheric pressure. When you raise the pressure of water (such as in a steam boiler), the boiling temperature of the water also rises. The same is true of lowering the pressure; the boiling point of the water also lowers.

What is happening is that when your system is hot and your pump comes on, it's lowering the pressure of the water immediately before the pump's suction intake. It's lowering the pressure far enough to drop the boiling point of the water, and the water is flashing into steam. All those little bubbles of steam (steam is a gas) then get sucked into the pump where they slam against the impeller and casing, making that awful noise. The reason you don't get the noise when your system is cold, is because the pump is not lowering the pressure enough to bring the water to its corresponding boiling point - but as soon as the system heats up enough, it will, and you'll get the noise.

The cushion tank maintains a constant pressure on the system in its immediate vicinity. So, having the pump suction intake installed downstream of the cushion tank ensures that there is always enough pressure in the line, so that when the pump comes on, it can't lower the pressure enough to affect the boiling point of the water. No pressure change, no flashing steam, no cavitation. That's why isolating the cushion tank had no effect; it currently isn't in a position to make any difference anyway. Your best bet is to stick with your original plan to move the circulator.

brucewo1b

Difficult problem -- crackling noise in pipes

Well people, I've moved the pump to the suppy, and no luck. Still have the same noise in the pipes in the same location. Maybe it's air, but there are no bleed valves in that section of piping. All other bleed valves have no air. Do I just have to live with this noise? Might it mysteriously dissappear after some time..