Water Hammer

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jebmke
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Water Hammer

Post by jebmke »

I am using a timer on a garden sprinkler that shuts the water off suddenly. I installed this device between the hose bib and the hose expecting it to eliminate the hammer but it sounded like the problem persists.

https://www.amazon.com/gp/product/B000H ... UTF8&psc=1

Is there some other solution? If I put the timer at the end of a short hose (e.g. 10 feet) and then extend the longer hose from there will the short hose absorb the hammer?

edit for clarity: the anti-hammer device is connected directly to the faucet; the timer follows and the hose is attached to the timer.
Last edited by jebmke on Mon Sep 20, 2021 10:37 am, edited 1 time in total.
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David Jay
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Re: Water Hammer

Post by David Jay »

I believe that it needs to go on the supply side of the timer, not between the timer and the hose.

Anything that has the ability to expand-and-contract will help, so a section of hose between the tap and the timer (as you suggested) will also help.
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Re: Water Hammer

Post by Sandtrap »

David Jay wrote: Mon Sep 20, 2021 8:48 am I believe that it needs to go on the supply side of the timer, not between the timer and the hose.

Anything that has the ability to expand-and-contract will help, so a section of hose between the tap and the timer (as you suggested) will also help.
+1
Supply side. "Before" the shutoff valve.

good catch.
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jebmke
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Re: Water Hammer

Post by jebmke »

David Jay wrote: Mon Sep 20, 2021 8:48 am I believe that it needs to go on the supply side of the timer, not between the timer and the hose.

Anything that has the ability to expand-and-contract will help, so a section of hose between the tap and the timer (as you suggested) will also help.
My op was poorly worded. It is installed between the bib and the timer. The hose is connected to the outbound side of the timer. Yet, I still get hammer.
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Re: Water Hammer

Post by Chip »

There's a chance that it is defective.

I have installed one of these on some household plumbing to stop water hammer. It worked well for a couple of years, then failed. On examination I could see that the piston that is supposed to move to absorb the shock had moved out of position toward the closed end of the arrestor. To the point where it could no longer absorb the shock. I replaced it and the hammer is gone.

Another possibility is that it isn't large enough, though I think that's unlikely. But it could be the case if there's a long run of pipe to the outside spigot.

It looks to me like what you have is this arrestor screwed into the hose adapter fitting. If you're planning on buying a new one (vs. returning) you might be able to buy just the arrestor and reuse the fitting. Assuming you can get them apart.

I actually bought 2 of the arrestors last time so that I have one handy if the one in service fails.

FWIW, I always use supplyhouse.com for plumbing supplies. They have great prices and fast (but not free) shipping.
Californiastate
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Re: Water Hammer

Post by Californiastate »

The arrestor and/or air chamber needs to be before the shutoff device (solenoid). I have doubled up the arrestors at my automatic washing machine. I need to replace them every few years when they saturate.
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jebmke
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Re: Water Hammer

Post by jebmke »

Californiastate wrote: Mon Sep 20, 2021 10:31 am The arrestor and/or air chamber needs to be before the shutoff device (solenoid). I have doubled up the arrestors at my automatic washing machine. I need to replace them every few years when they saturate.
it is; see my later post. Arrestor is attached to the hose bib; shut-off device next, then hose. My first post was not clear.
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Yooper
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Re: Water Hammer

Post by Yooper »

jebmke wrote: Mon Sep 20, 2021 10:37 am
Californiastate wrote: Mon Sep 20, 2021 10:31 am The arrestor and/or air chamber needs to be before the shutoff device (solenoid). I have doubled up the arrestors at my automatic washing machine. I need to replace them every few years when they saturate.
it is; see my later post. Arrestor is attached to the hose bib; shut-off device next, then hose. My first post was not clear.
I installed the exact same product on my washing machine. Interestingly enough, it seemed like there was a "break-in" period where the hammer was still noticeable. But after a few days, perhaps even a week (it's been years now) the hammer disappeared completely.
csmath
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Re: Water Hammer

Post by csmath »

I've always just sweat a vertical copper run on the interior before any water fixture, usually inside the wall. I'm not familiar with this specific device but am curious if the installation directions mention anything about proper orientation of installation. Make sure it doesn't need to be installed vertically to maintain air in the cavity for compression.
criticalmass
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Re: Water Hammer

Post by criticalmass »

jebmke wrote: Mon Sep 20, 2021 8:20 am I am using a timer on a garden sprinkler that shuts the water off suddenly. I installed this device between the hose bib and the hose expecting it to eliminate the hammer but it sounded like the problem persists.

https://www.amazon.com/gp/product/B000H ... UTF8&psc=1

Is there some other solution? If I put the timer at the end of a short hose (e.g. 10 feet) and then extend the longer hose from there will the short hose absorb the hammer?

edit for clarity: the anti-hammer device is connected directly to the faucet; the timer follows and the hose is attached to the timer.
I use that same device (or a similar model) on my washing machine. It worked well for maybe 3 years of light use, then the piston got stuck down the bore near the top dead end, rendering it useless. I suspect sediment eventually gets in the way of the piston sleeve. Anything big wouldn’t make it through the screen I have on the connection.

I decided to find another brand, but the only brand sold at Home Depot nearby was now a different company, made in China.

I ended up buying another Sioux Chief and hope it lasts longer. I noticed the design had changed slightly.

Take a look inside. Is the piston at the far end from the opening where you can look in? If so, it is bad and replace under warranty.

When they work, they work well.
Also check your water pressure. If it is over 50 psi, get a pressure reducing valve on city water, or turn down the limit switch with a well.
Speckles
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Re: Water Hammer

Post by Speckles »

Most/many outside hose bibs contain a back flow preventer to prevent potentially contaminated water from flowing backwards into the clean water supply. Most plumbing codes require this.

I suspect your hose bib may contain a back flow preventer which acts as a barrier between the hammer arrester you installed and the inside piping. I suspect that the water hammer arrester would prevent the water hammer if it was installed upstream of the outside hose bib (and back flow preventer). Unfortunately, this might be difficult to do. Good luck.

Specks
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Re: Water Hammer

Post by Californiastate »

csmath wrote: Mon Sep 20, 2021 8:49 pm I've always just sweat a vertical copper run on the interior before any water fixture, usually inside the wall. I'm not familiar with this specific device but am curious if the installation directions mention anything about proper orientation of installation. Make sure it doesn't need to be installed vertically to maintain air in the cavity for compression.
IIRC the UPC started requiring arrestors on quick closing fixtures in the late 90s. Up until then, around here, SF was the only area that required any sort of air chamber. Air chambers eventually saturate and are rendered useless until they are drained and refilled. Modern arrestors usually can be mounted in any position. I've over heated sweat arrestors too much and you can hear the chamber pop. Some arrestors can be buried in a wall but most require access for replacement.
Financial Engineer
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Re: Water Hammer

Post by Financial Engineer »

jebmke wrote: Mon Sep 20, 2021 9:44 am My op was poorly worded. It is installed between the bib and the timer. The hose is connected to the outbound side of the timer. Yet, I still get hammer.
I am so glad that water hammer (one of my favorite professional challenges) has united with my favorite website (Bogleheads) and I cannot resist posting even though previous posters have also provided very good information.

I have 2 Main points to mention with a 3rd to link the first 2 together:
1.) The Sioux Chief Mini Restor you linked in your original post can absorb "upsurges" (i.e., upward spikes in pressure) since the Mini Restor maintains a volume of air behind a sealed sliding piston. The air gets compressed as the upsurge pushes the piston into the cylinder - thereby compressing the air and giving the upsurge a place to dissipate - eventually the piston returns to it's original position once the pressure surges subside. I mention this because understanding how it operates it may assist in determining the proper place to locate the device.
2.) The timer sounds like a solenoid (an electrically actuated usually quick closing valve). Quick closing valves create upsurges on the upstream side (the side from which the water is coming) of the valve upon closure and downsurges on the downstream side of the valve (opening a valve quickly does the inverse - upsurge downstream and downsurge upstream - in case you are curious). Quick closing solenoids are common on modern washing machines and ice makers and I have successfully used the exact Sioux Chief Mini Restor you bought to resolve shaking pipes upstream of my washing machine that were caused by the solenoids in the washing machine.
3.) Conclusion: Given that upsurges are triggered upstream of quick closing solenoids (or any quick closing valve for that matter) and Sioux Chief Mini Restors alleviate upsurges the Mini Restor should be placed upstream of the solenoid (in your case the timer). Doing this should resolve the hammer you experience inside your house.

PS - in case anyone is interested I could post some interesting high speed pressure graphs I took in my home both with and without a Mini Restor - the measurements I took illustrate very clearly that these Mini Restors do indeed minimize water hammer upsurges.

PSS - please report back if making the above adjustment resolves the water hammer or not.
Last edited by Financial Engineer on Tue Sep 21, 2021 10:35 pm, edited 1 time in total.
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Re: Water Hammer

Post by snackdog »

I get water hammer from what I think is my cistern pump turning on/off. I do have a pressure accumulator that is holding pressure so I assume it is working ok. This only occurs when my 5 hp summer pump is in use and not when I switch to the 1/2 hp winter pump. Thoughts?
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Re: Water Hammer

Post by Financial Engineer »

snackdog wrote: Tue Sep 21, 2021 9:20 pm I get water hammer from what I think is my cistern pump turning on/off. I do have a pressure accumulator that is holding pressure so I assume it is working ok. This only occurs when my 5 hp summer pump is in use and not when I switch to the 1/2 hp winter pump. Thoughts?
Questions:
1.) Could you take a photo of the "pressure accumulator" and post, or link to the product online? - a photo of the entire setup would also be helpful for troubleshooting.
2.) Do you get hammer on start up and shut down or only one or the other?

That the problem is worse with the bigger pump makes sense because water hammer pressure spikes are proportional to the velocity change the water goes through after the pump shuts down. Larger pumps have a larger change in velocity when they shut off - and therefore larger water hammer pressure surges.
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Re: Water Hammer

Post by Financial Engineer »

jebmke wrote: Mon Sep 20, 2021 10:37 am
Californiastate wrote: Mon Sep 20, 2021 10:31 am The arrestor and/or air chamber needs to be before the shutoff device (solenoid). I have doubled up the arrestors at my automatic washing machine. I need to replace them every few years when they saturate.
it is; see my later post. Arrestor is attached to the hose bib; shut-off device next, then hose. My first post was not clear.
Now that I realize you already have the Mini Rester placed upstream of the solenoid (yet you are still experience hammering) could you please clarify something. Is the water hammer that you experience in the hose or in the house or both?
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jebmke
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Re: Water Hammer

Post by jebmke »

Financial Engineer wrote: Tue Sep 21, 2021 10:34 pm Now that I realize you already have the Mini Rester placed upstream of the solenoid (yet you are still experience hammering) could you please clarify something. Is the water hammer that you experience in the hose or in the house or both?
I heard it fairly pronounced when inside the house. Sounded like the pipe. I have since run a short (15 foot) hose from the arrestor to the timer and that seems to help quite a bit. I am now wondering if I should put the arrestor at the downstream end of that 15 foot hose (before the timer). About to rain like a banshee here so will be a while before I really test it again.
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Re: Water Hammer

Post by Chip »

jebmke wrote: Wed Sep 22, 2021 8:01 am I heard it fairly pronounced when inside the house. Sounded like the pipe. I have since run a short (15 foot) hose from the arrestor to the timer and that seems to help quite a bit. I am now wondering if I should put the arrestor at the downstream end of that 15 foot hose (before the timer). About to rain like a banshee here so will be a while before I really test it again.
It makes sense that the 15' length of hose would absorb some of the overpressure.

Have you tried to examine the arrestor to see if it is defective? Several of us have mentioned that possibility.
Financial Engineer
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Re: Water Hammer

Post by Financial Engineer »

Chip wrote: Wed Sep 22, 2021 8:10 am
jebmke wrote: Wed Sep 22, 2021 8:01 am I heard it fairly pronounced when inside the house. Sounded like the pipe. I have since run a short (15 foot) hose from the arrestor to the timer and that seems to help quite a bit. I am now wondering if I should put the arrestor at the downstream end of that 15 foot hose (before the timer). About to rain like a banshee here so will be a while before I really test it again.
It makes sense that the 15' length of hose would absorb some of the overpressure.

Have you tried to examine the arrestor to see if it is defective? Several of us have mentioned that possibility.
+1 examine the arrestor
+1 agree that the flexible hose can also absorb some of the pressure

As far as which side of the hose is better at alleviating hammer in the house I think you are in a good position to tell us by performing an experiment - I am not able to predict. But if you do not want to risk popping the 15 ft hose due to material fatigue I think it will be better to put the arrestor between the solenoid timer and the 15 ft hose. In large scale civil engineering applications similar to this we try to place the "arrestors" (aka surge tanks) as close as possible to the source of the pressure spike (which in this case is the solenoid timer) to avoid damage to more distant equipment and materials. Would love you to post the results if you perform an experiment.
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Financial Engineer
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Re: Water Hammer

Post by Financial Engineer »

Californiastate wrote: Mon Sep 20, 2021 10:49 pm
csmath wrote: Mon Sep 20, 2021 8:49 pm I've always just sweat a vertical copper run on the interior before any water fixture, usually inside the wall. I'm not familiar with this specific device but am curious if the installation directions mention anything about proper orientation of installation. Make sure it doesn't need to be installed vertically to maintain air in the cavity for compression.
IIRC the UPC started requiring arrestors on quick closing fixtures in the late 90s. Up until then, around here, SF was the only area that required any sort of air chamber. Air chambers eventually saturate and are rendered useless until they are drained and refilled. Modern arrestors usually can be mounted in any position. I've over heated sweat arrestors too much and you can hear the chamber pop. Some arrestors can be buried in a wall but most require access for replacement.
I live in MN and for what it's worth I have noticed that older homes in St. Paul have air chambers at the point where the service enters the house. The chambers consist of a capped vertical pipe (~2" diameter - ~3 ft tall). This practice must have been abandoned since they require repeated draining of the system to keep the air pocket in the air chamber since air under pressure will dissolve into the water over time. The chamber could also serve as a focal point for bacterial growth (not ideal in a drinking water systems :( ). In present day applications surge tanks (large scale air chambers) have bladders to separate the water from the air, or air compressors that replace the air in the tank as it dissolves.
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