Pipes groaning

[mschrank]

This just started a couple months ago. No recent plumbing work.

When a tap is opened, the pipes make a sound like a trombone player warming up. Low, then high, then back to low, then quiet.

It isn't limited to one faucet, toilet or shower head...all of them cause this noise.

It only does it when the flow starts, then stops after 2-5 seconds. If I turn off the tap, then turn it back on within about 10-15 seconds, no noise.

I can't isolate exactly where it's coming from...somewhere in the basement where the pipes are inside a wall. Seems to be about 5-10 feet beyond the PRV.

Anybody know what's causing this? It's not entirely unpleasant, except when someone flushes a toilet in the middle of the night....

[atgcpaul]

I think they said on Ask This Old House this is because of some kind of
obstruction in the pipes.

I also found this article with some remedies:

http://www.plumberhelper.com/do-your...-on-the-water/

[LCHIEN]

not sure this is it but there are some risers in your pipes - vertical runs that dead-end with a cap - that are supposed to act as dampers when you start or stop water flow. Its supposed to trap air in the vertical section which compresses to provide the damping. It's very effective against hammering noises that occur when you start and stop water flow. Maybe its also responsible for the noises you hear on start and stop.

If somehow over a long time (many years) the risers lose the air - it gets absorbed into the water gradually, or maybe the cap leaks a tiny bits of air molecules, the riser fills with water and it doesn't do its job.

The solution to refill the riser with air is easy. Just turn off the main water entry. Then turn on all the faucets to drain the pipes and let them fill with air, at least the high spots, like the risers. Then turn the water back on. Now you should fill the pipes but the risers will be full of air again and work.

[Uncle Cracker]

Loring may be right about the risers. Since liquid water cannot compress, but air can, these air pockets would serve to mitigate pressure waves and reduce the chance of water hammer. This is different from air pockets actually in the pipe runs, which could have the opposite effect, and contribute to water hammer. If you introduce air into your piping system to recharge any dead-end risers, make sure you slowly open all outlets when re-introducing water, so you can purge remaining air from the other piping, or else you'll soon be findin' where your weakest pipe joints are...

[Mr__Bill]

What you may be hearing is the water pipe move against the wood. Fresh hot or cold water will make the pipe expand or contract just a little and it moves. This is really noticeable with hot water heat. They make pipe support brackets with what looks like a nylon bushing to allow the pipe to move. If you can hold on to the pipe when the water is turned on you should be able to feel the vibration when it moves. With lots of testing you may find he spot that is too tight. On the other hand it may just be a Pooka moving about.

Bill
From ghoulies and ghosties and long-legged beasties, and things that go bump in the night, good Lord deliver us.
Old Cornish prayer.

[gerti]

From the description I'd say it is an obstruction, or (quite likely) a shutoff valve that is only partially opened.

[Uncle Cracker]

Thinking also that, if the piping is steel or other metal, there may be a scale layer built up inside thick enough to restrict flow. A given demand now has less cross-sectional area to flow through, so it must now flow faster. The increased velocity can cause all kinds of noises, not to mention making the pipes more apt to move, as Gerd has suggested.

[LCHIEN]

i may not be tight about air (or lack of) in the risers, but its very simple and no cost to try, before anything else. Lack of compressible air in the risers may also lead to howling noises not being damped out quickly.

[mschrank]

The solution to refill the riser with air is easy. Just turn off the main water entry. Then turn on all the faucets to drain the pipes and let them fill with air, at least the high spots, like the risers. Then turn the water back on. Now you should fill the pipes but the risers will be full of air again and work.

Should have mentioned I already tried this. It seemed to help initially, but then the groaning/tromboning returned.

I think they said on Ask This Old House this is because of some kind of
obstruction in the pipes.

I also found this article with some remedies:

That's what my dad thought, since the "musical quality" of the sound is reminiscent of a reed in a clarinet. I'll try the suggestion in the article you linked to (thouroughly flushing the pipes). But, if it is this, I'm thinking the sound wouldn't go away after a couple of seconds. Wouldn't it continue as long as water is running?

What you may be hearing is the water pipe move against the wood. Fresh hot or cold water will make the pipe expand or contract just a little and it moves. This is really noticeable with hot water heat. They make pipe support brackets with what looks like a nylon bushing to allow the pipe to move. If you can hold on to the pipe when the water is turned on you should be able to feel the vibration when it moves. With lots of testing you may find he spot that is too tight. On the other hand it may just be a Pooka moving about.

Not a Pooka because it happens in daylight hours, too. I really hope it's not a pipe rubbing a bracket or stud, since all of the pipes are inside the walls.

From the description I'd say it is an obstruction, or (quite likely) a shutoff valve that is only partially opened

I'm pretty sure they are all fully opened, but I'll check again.

Thanks for all your suggestions...I'll post back if any of these help!

[Tom Slick]

is your main shutoff a ball valve or globe valve? try turning it off then all the way on.