Rumbling/banging pipes...when there is no flow?

Submitted by hotpepperz t3_zpd3xe in DIY

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Main Shut-off, water on the rubbermaid lid

Looking for help troubleshooting… copper pipes have been rumbling/banging for the past 4 weeks. Low rumbling wind sound and middle of the night is louder, more frequent hammer/rattle, every 10-15mins. Most active and loud around 3-4am. Daytime it's subtle but still there.

Thinking it might be flow so I turned off all house fixtures (left the main valve open) and confirmed rumble/bang still happens.

Put my ear to the pipe at the house shutoff I can hear the noise inside the pipe, and when I shut the valve it stops rumbling/banging on the house side, but can still hear it on the city's supply side. So every night I have been turning off the main shut off valve so we don't get the banging and can sleep and then turning back on in the morning.

Took a better look today and see that there is some recent water under the shut off valve on a Rubbermaid tub. Threads on the stem were damp. But not actively leaking.

My theory...I think the city's system is somehow "surging" pressure or air into my house and causing the vibrations/noise...and the slamming forces water out the threads. Maybe a faulty municipal PRV or pump cut-off setting?

Does this make any sense to others?...

Anyhow..thinking my best course of action is to replace shut-off valve and add either a household PRV and/or pressure arrestor? what would you include in the assembly?

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Idea

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Comments

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CanadianBaconMTL t1_j0s96iq wrote

Measure the water pressure, of it's above normal (google it) you'll need that pressure thing, the arrestor is definitely a good idea but it should be after the valve not before.

My guess is there is a leak on the city side, call the city and ask to close the valve on the city side

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hotpepperz OP t1_j0t3o62 wrote

Hey thanks appreciate this. I’m calling them tomorrow. -30C, ouch. Will post back once we get to the bottom of it in the next week or so.

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MasterLow t1_j0t7q67 wrote

New shutoff valve, add a PRV and probably some water hammer arrestors on both hot and cold, or just the cold at least. A one way directional valve fitting would eliminate anything happening behind it, if you install it right after your shut off valve. Had to add a one way valve fitting right before my tankless fitting since any time any cold water was used the water heater would turn on from the tiny amount of cold water moving.

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Sluisifer t1_j0vn6u9 wrote

You likely caused the leak by using the valve. That's very common with old gate valves. There's usually a packing nut you can tighten down to stop it, but ultimately the valve may need replacing.

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hotpepperz OP t1_j1vua7i wrote

So it warmed up from -40C to 0C this week (that's -40F to 32F for the folks in the US)...and what do you know - there's a pool of water bubbling up from the middle of the street! Definitely a leak somewhere in the city system and causing air/noise/pressure to travel up my copper service and bang in the house. Excavators coming later this week! :)

I'm still going change out my old valve for a new ball valve, but don't think I'll need the PRV/arrestor after the city's fix is done.

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