How to confirm water hammer??

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phelpdk

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This past winter I starting noticing a LOUD thudding noise that vibrates my whole house. At first it would only last 15 - 20 seconds. As it was seemingly coming from my basement where all the mechancial "guts" of my home are, my first guess was that it was my hot water heater vibrating from scale build up. I flushed my hot water heater and it didn't resolve. My next thought was that it was the basement bathroom vent. I tested that, and elimnated that option. The sound/vibration has continued and gotten stronger and lasts longer and longer now. However, it doesn't happen daily or at a regular time. It happens regardless of whether my HVAC system is on or not. I also haven't been able to determine any correlation between specific faucets or plumbing fixtures. In googling to figure out the problem I came upon "water hammer", and if this video:
is an accurate representation of what "water hammer" sounds like, then I strongly suspect that's what's happening. However, as I cannot induce the sound "on command", I'm hesitant to call a plumber as there is no way to know if the sound will occur for him/her to diagnose. Given everything I've read about water hammer and its indication of potential major problems, and the fact the noise is lasting several minutes now and the vibrating is getting strong I'm pretty concerned. Any guidance on how to try and reliably induce the sound and/or confirm it is water hammer would be very greatly appreciated!!
 

John Gayewski

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Water hammer happens when a valve closes. Anything that uses water and then shuts off can cause water hammer. To test for it but a tattle tale gauge and check it. There will be spikes recorded that max out the gauge.
 

Mr tee

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Water hammer would most often be one "bang" when a valve closed quickly.
 
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phelpdk

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Water hammer would be one "bang" when a valve closed quickly.
What then would you describe the noise in the linked YouTube video in the OP as then? The noise I'm experiencing is nearly identical.
 

phelpdk

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Water hammer happens when a valve closes. Anything that uses water and then shuts off can cause water hammer. To test for it but a tattle tale gauge and check it. There will be spikes recorded that max out the gauge.
Any guidance on where to acquire such a gauge? Everything I see when googling is ~$200, which I'd really rather not spend, especially if I'm going to have to hire a plumber to fix the problem. :/
 

WorthFlorida

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Water hammer would be one "bang" when a valve closed quickly.
What phelpdk is hearing the initial shock wave is bouncing back and forth from one end to the other in the plumbing. Just like an echo. When a water hammer starts usually something has changed. Could be the water pressure has increased, any existing arrestors may have failed or are water logged. Is there an expansion tank off the water heater?

Recently we had one post that it was noticed the one bang hammer started after he replaced the kitchen faucet. The cause was the new lines from the faucet were very ridged (PEX like) where as the old ones were braided nylon hoses that were able to absorb the shock.

You'll need to do what John Gayewski suggests, get a gauge that fits on a hose spigot and see what is going on.
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John Gayewski

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Water hammer isn't always just one bang. It can sound like a machine gun (not exactly like a machine gun) rapid firing as a valve is closed slowly.
 

John Gayewski

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If there is a gate valve at any point in the system it needs to be all of the way open or all of the way closed. A gate valve will notoriously cause machine gun water hammer when throttled.
 

Reach4

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Water hammer isn't always just one bang. It can sound like a machine gun (not exactly like a machine gun) rapid firing as a valve is closed slowly.
I would call what you described an oscillation or resonance or a chattering.
 

Jeff H Young

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some of us use different words I call that a water hammer if its a single bang or machinegun sound to me its still a water hammer right or wrong that's how I describe it. but its helpful to give detail on type of sound.
sometimes a washer inside a faucet or angle stop does that . I think a water pressure regulator can do that , I had one making some strange noises a while ago pretty loud cant remember the sound though . BTW the pressure gauge is 10 bucks at home depot
 

phelpdk

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Thanks everyone for their insight! The noise hasn't occured again since I originally posted. However, I have contacted my county to come do a water pressure check, and they'll be here tomorrow. I have a few questions though as I continue to try and figure this out:

1. My housemate let me know that when it last happened, if he turned on his bathroom sink faucet (he lives in the basement) it got worse. If it were indeed water hammer, wouldn't opening a line (ie., the faucet) let the air out and cause the noise to stop? Or since his bathroom is in the basement would the air not travel in that direction?
2. Does water hammer get worse over time? I don't think I was clear enough in my first post, in that this noise is now lasting several minutes. This is compared to the 20 - 30 seconds it was back in December. It doesn't feel as though the vibration is any stronger though, it's just lasting significantly longer.
3. Do water arresters have to be installed wherever the "problem" is? As in, do I need to determine the source of the problem before I have one installed?

Thanks again, all!
 

Jeff H Young

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The hammer doesn't get better on its own something has to change , also even harder to explain it doesn't just start for no reason .
Water hammer arrestors often don't fix the problem . they sometimes help and sometimes don't
Go get the 10 dollar gauge I know saving 10 bucks is good but it might come in handy
 

Reach4

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Any guidance on where to acquire such a gauge? Everything I see when googling is ~$200, which I'd really rather not spend, especially if I'm going to have to hire a plumber to fix the problem. :/
Any place with lawn watering supplies will probably have a garden hose thread pressure gauge.. A hardware store or a farm store will have them. Under $20.
 

Reach4

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Thanks everyone for their insight! The noise hasn't occured again since I originally posted. However, I have contacted my county to come do a water pressure check, and they'll be here tomorrow. I have a few questions though as I continue to try and figure this out:

1. My housemate let me know that when it last happened, if he turned on his bathroom sink faucet (he lives in the basement) it got worse. If it were indeed water hammer, wouldn't opening a line (ie., the faucet) let the air out and cause the noise to stop? Or since his bathroom is in the basement would the air not travel in that direction?
Air does not cause water hammer.

Do you have a PRV (pressure reducing valve)? The county people may be able to help you with knowing that.
 
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