Water Hammer Preventer Installation Guide

Water hammer control location, codes, manuals, sources
Cure banging water pipe noise

Water hammer noises in plumbing is also called hydrostatic shock.

Here we explain how, why, and where to install a device to control water hammer, stop hydrostatic shock, and stop the horrible banging pipe noises caused by that problem.

Model building codes require that a "manufactured" water hammer arrester be installed as close as possible to quick-closing valves to reduce hydraulic shock in the water system when the valve closes, thus reducing the risk of leaks or damage to the plumbing system or to fixtures or devices attached to it.

"Manufactured" means that the device complies with ASSE 1010 and is designed to avoid losing its air charge.

Note also that the model or adopted plumbing codes, when discussing water hammer arresters, do not distinguish water supply pipe material. That's because the arrestor must protect all plumbing components: piping, valves, fixtures, etc. regardless of composition.

Article Contents

• WATER HAMMER ARRESTOR SIZE & LOCATION SPECIFICATIONS
• WATER HAMMER ARRESTOR PLUMBING CODES, INSTALLATION GUIDES & INSTRUCTION MANUALS
• WHERE TO BUY WATER HAMMER ARRESTORS

Photo just above: an Oatey "Quiet Pipes" water hammer arrestor for sale at a Home Depot supply store.

This device is marked as complying with ASSE1010, so we know that this is a manufactured water hammer arrester, so it should not lose its air charge.

Where do I install the water hammer arrestor?

Andy said:

I've recently replaced a booster pump in my residence. This new pump switches on Immediately on noting a pressure drop (water being used) versus the old one which had a timer delay before powering on.

I installed a Honeywell pressure reducer on the supply side of the pump and my total pressure is around 60.

All should be good - but when water is used, there is quite a hammer going on.

The hammer appears to be on the supply side of the pressure reducer/pump (because I hear a copper bang) versus on the output side of the pump (house flow which is plastic).

I thought about maybe installing an arrestor, but since the hammer is on the supply side, I have no idea where to install it. I also find it odd that I have a hammer on the supply side.

Any advice would be appreciated. The pump vendor is suggesting a pressure tank on the output side, but until I understand what is going on, I don't want to start modifying plumbing. Thanks. - 2 Nov 2015

Reply: install the water hammer arrestor close to the noisy valve or control or use a special model

Indeed I'd install a water hammer arrestor on the side of equipment, valve, or device where the hammering appears to occur; Anywhere close to that point should work.

Usually we install the water hammer arrestor between the shutoff valve and the incoming water supply line - close to the valve.

Or we may need to install a water hammer arrestor on both hot and cold water piping systems.

If that doesn't work for you I suspect the water hammer arrestor was not properly sized. Typically a smaller residential-type water hammer arrestor has 1-2 cubic inches in volume and can handle one to four plumbing fixtures. For example a Sioux-Chief 660-series water hammer arrestor contains 1.4 cubic inches.

A different model of water hammer arrestor (such as the Sioux-Chief 660-GTR-series arrestor) is designed for installation at water supply valves on hot or cold water piping systems - you should consider this option.

For severe water hammer problems or in commercial or larger installations with more fixtures or larger diameter water piping (and perhaps with faster water velocities) Sioux-Chief provides a series of higher capacity (larger) water hammer arrester devices in its 650-series water hammer arresters.

The 650-series water hammer arrester is sold in six sizes (A through F) and contains from 5 to 36 cubic inches of volume.

The smallest of the 650 series water hammer arrester contains 5 cubic inches in its pressurized air cushion and can support 1-11 plumbing fixtures while he largest water hammer arrester (Model 660-F at 36 cu. in.) can support from 155 to 330 plumbing fixture units.

Even larger volume, height and diameter water hammer arresters are available for special applications.

Here is what water hammer manufacturers say about water hammer arrestor size and location:

"The location should be at the piping serving the fixture(s) and normally between the last two fixtures. " - J.R. Smith Manufacturing Co. (Op. cit.)

"Water hammer arresters shall be specifically sized and have sufficient volume of air to dissipate the calculated kinetic energy generated by closing residential or commercial faucets or valves. Arresters shall be installed on both hot and cold lines on the supply stops where applicable.

Arresters shall be approved for installation with no access panel required.

Water hammer arresters shall be ANSI/ASSE 1010 2004 certified. " - Sioux Chief Manufacturing Co. (Op. cit.)

Water Hammer Arrestor Plumbing Codes, Installation Guides & Instruction Manuals

• ANSI/ASSE 1010 - 2021 Performance Requirements for Water Hammer Arresters [ANSI Web store] - for purchase, $45. U.S.
  
  Website excerpt:
  
  Water hammer arresters are installed on water distribution system piping to prevent detrimental surge pressures within water distribution systems, thereby prolonging the service life of valves, piping, fittings, trim, equipment, appliances, appurtenances, and other devices which are part of the distribution system; and to eliminate noise.
  
  This standard applies only to those devices classified as water hammer arresters having a permanently sealed cushion of gas isolated from the water way, and designed to provide continuous protection, without maintenance, against detrimental surge pressures within the water distribution system.
• Sioux Chief WATER HAMMER CONTROL Engineer Report [PDF local copy], (2012), Sioux Chief, 24110 South Peculiar Drive, Peculiar MO 64078, Tel: 1-800-821-3944, Website: www.siouxchief.com, retrieved 2017/04/02, original source: http://www.siouxchief.com/docs/default-source/print/print-brochures/supply/water-hammer-arresters---engineer-report.pdf - copy on file as Water-Hamer-Manual-SiouxChief.pdf
  
  Excerpts:
  
  The report is a technical resource for plumbing engineers that addresses uncontrolled water hammer and its damaging effects to plumbing and piping systems.
  
  The term “water hammer” is used to describe the pressure surges, noise, and destructive forces associated with the transfer of kinetic energy into the piping system due to an abrupt change in velocity of a non-compressible fluid.
  
  Water hammer is commonly identified as the loud banging sound which can result from shutting water off quickly, for example on a faucet or washing machine.
  
  “The kinetic energy formula shows us that the pressure rise in metal pipe due to a sudden change in velocity is approximately 60 times the original flow velocity in feet per second,” said Vice-President and Senior Product Group Director, Michael Meagher.
  
  “So a common half inch supply line, flowing at 6 fps, can generate a pressure rise of 360 psig above and beyond the flow pressure itself.”
  
  ...
  
  "Since air chambers made from a piece of vertical pipe do not provide acceptable protection, pre-manufactured water hammer arresters are required to address this potential problem. 2.2.10.15. (1)
  
  Water Hammer Arresters:
  
  Water hammer arresters shall conform to ASSE 1010."
  
  Since 1957, Sioux Chief has manufactured innovative plumbing products. It is a leader in providing rough plumbing solutions for residential, commercial, industrial and government applications.
  
  Sioux Chief’s comprehensive product line is comprised of three core groups: Supply, Drainage and Support. Sioux Chief products are sold to qualified wholesale distributors and retailers worldwide. The company is headquartered in Peculiar, Missouri — just outside of Kansas City.
• WATER HAMMER ARRESTOR SIZING, Watts Series 15 & LF15 [PDF], from 1/2" to 2" pipe diameters, (2010), retrieved 2017/04/02, original source:
  Watts®, Watts Water Technologies, 815 Chestnut St., No. Andover MA 01845, USA, Website: www.watts.com
  Watts®, Watts Water Technologies, 5435 North Service Rd., Burlington, ONT, L7L 5H7, Website: www.wattscanada.ca
• WATER HAMMER ARRESTOR SIZING, MIFAB® [PDF], MIFAB, Inc., 1321 West 119th St., Chicago IL 60643-5109, USA, Tel: 1-800-465-2736, Email: sales@mifab.com, Canada Tel: 1-800-387-3880, retrieved 2017/04/02, original source: http://www.mifab.com/Catalog/Library/wha-sizing-guide.pdf
• WATER HAMMER ARRESTOR GUIDE & CODES, Watts [PDF], retrieved 2017/04/02, op. cit., original source: http://media.wattswater.com/F-WHA.pdf, sizing tables for water arrestors, plumbing code compliance citations,
  
  UPC Plumbing Code Excerpt on Water Hammer
  
  
  609.10 Water Hammer.
  
  All building water supply systems in which quick-acting valves are installed shall be provided with devices to absorb the hammer caused by high pressures resulting from the quick closing of these valves.
  
  These pressure-absorbing devices shall be approved mechanical devices. Water pressure-absorbing devices shall be installed as close as possible to quick-acting valves.
  
  IPC Plumbing Code Excerpt on Water Hammer
  
  604.9 Water Hammer.
  
  The flow velocity of the water distribution system shall be controlled to reduce the possibility of water hammer. A water hammer arrestor shall be installed where quick-closing valves are utilized.
  
  Water hammer arrestors shall be installed in accordance with the manufacturer's specifications. Water hammer arrestors shall conform to ASSE 1010.
• WATER HAMMER ARRESTOR INSTALLATION GUIDE, Watts LF150A/LF150-HA, [PDF] retrieved 2017/04/02, original source: op. cit. (LF - "Lead Free" - Ed.)

Where to Buy Water Hammer Arrestors - water hammer suppression products

The following companies are producers of water hammer arresters (water hammer arrestors in some texts) distributed pretty-much world wide:

Ayrlett (piston type water hammer arrester), MiFab, Oatey, IPS, Jay R Smith, JB Products, Sioux Chief, Viega, Water-Tite, Precision Plumbing Products, Wade Watts, Wilkins, Zurn

• Ayrlett Water Hammer Arresters [Website] Piston Type, 6851 Enterprise Drive, South Bend, Indiana 46628 USA, P: 574-288-0607 Email: JBOrders@jb-products.com
• Blacoh™ Fluid Control, Website: http://www.blacoh.com, Tel: 951-239-3930, BLACOH Fluid Control, Inc. 601 Columbia Ave, Bldg D Riverside, CA 92507 USA Phone: 888.494.3179 951.239.3930 Fax: 951.342.3101 Email: sales@blacoh.com
  
  Blacoh sells Sentry pulsation dampeners and surge suppressors that (quoting):
  ... remove virtually all hydraulic shock, enhancing all-around performance and reliability of fluid flow in industrial and chemical transfer applications.
• Douststop Anti Hammer Water Control Valve, Doust, Australia, also available online from http://www.bunnings.com.au/
• FLOMATIC FOOT VALVE INSTALLATION INSTRUCTIONS [PDF] Flomatic Valves, 15 Pruyn’s Island, Glens Falls, New York 12801 Phone: 518-761-9797 Fax: 518-761-9798 www.flomatic.com retrieved 2022/03/23, original source: https://www.flomatic.com/assets/pdf_files/oem/16048.pdf
  
  Note: these instructions have a helpful discussion of water hammer -
• J.R. Smith Manufacturing, 2781 Gunter Park Dr. E. Montgomery, AL 36109-1405, USA, Tel: (800) 467-6484, Email: info@jrsmith.com, Website: http://www.jrsmith.com/
• Mifab Piston Type Water Hammer Arrestors [Website] MIFAB, Inc., 1321 West 119th Street Chicago, IL 60643 USA, Tel: 800.465.2736 email: sales@mifab.com
• Oatey Plumbingm Quiet Pipes Hammer Arrestors [Website] http://www.oatey.com/ Oatey U.S., 4700 W.160th Street Cleveland, Ohio 44135, USA, PH: (800) 321-9532, and Oatey Canada: 218 Wilkinson Road Unit 3, Brampton, Ontario Canada L6P 4M4, PH: (800) 321-9532 email: customerservice@oateyscs.com
• Silverstorm Water Hammer Arrestor, Australia, also available online from http://www.bunnings.com.au/
• Sioux Chief Water Hammer Arresters (shown above in AA size), Website: http://www.siouxchief.com,Sioux Chief, 24110 South Peculiar Drive Peculiar, MO 64078 USA, Phone 816-779-6104 800-821-3944, sold in Australia via https://www.masters.com.au
  
  Example: Sioux Chief 660-HB 3/4" water hammer hose arrestor, or Sioux Chief 660-TCO 1/4" water hammer arrestor tee for ice makers
• Reece Plumbing Centers, Australia [Website] water hammer arrestors by Ayrlett (piston type water hammer arrester), MiFab, Oatey, IPS, Jay R Smith, JB Products, Sioux Chief, Viega, Water-Tite, Precision Plumbing Products, Wade Watts, Wilkins, Zurn
• Watts Water Hammer Arrestors (Watt Series 05) or Watts Water Pressure Regulator (Watts Series 1156 or 25AUB) can correct water hammer water hammer-related leaks such as may occur at
  
  a BACKFLOW PREVENTER [web article] valve or temperature/pressure relief valve - Watts Water Products, 815 Chestnut Street, North Andover, MA, USA 01845-6098

• Zurn, WATER HAMMER ARRSTORS [Website] Zurn [PDF at the Zurn website] retrieved 2024/11/23, original source: https://www.zurn.com/media-library/web_documents/pages/technicalinformation/arrestor/wh-pg-03-pdf.aspx - copy on file as Water-Hammer-Arrestors-Zurn.pdf
  
  Excerpt:
  A Standardized Sizing System In an effort to arrive at a uniform method of sizing water hammer arrestors, members of the Plumbing and Drainage Institute (P.D.I.) sponsored a comprehensive testing program which lasted four years.
  
  As a result, there is now an industry-wide standard, P.D.I.-WH201, and the all-stainless-steel Zurn Shoktrol conforms with every aspect of this newly available information. A Simplified Sizing System
  
  Basically, the new standards establish six categories for water hammer arrestors (A, B, C, D, E, F). Each category sets down specific size and capacity requirements necessary to control shock in piping systems.
  
  “A” represents the smallest-sized unit; “F” denotes the largest size.

...

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2024-11-23 by RGlbk1 - Does ICC prohibit 18-inch air chamber water hammer arresters?

I thought the ICC no longer allows the 18” air chambers? Only the mechanical piston type or diaphragm type.

Illustration: a piston type water hammer arrester from Sioux Chief, designed to avoid losing the device's air charge, cited both below and above in more detail on this page.

Reply by InspectApedia Publisher (mod)

@RGlbk1,

Not exactly. It's not the size that makes some water hammer arresters no longer code compliant, it's the type. And of course you'll need to choose a water hammer arrester that is sized properly. See Zurn's example water hammer arrester sizing chart at the end of the article above on this page.

It's not only the 18-inch air chamber water hammer arrester that's no longer code-supported, but rather all of the older simple chamber-only type water hammer arresters.

So generally, yes, you're right that simple air chamber type water hammer arrestors are no longer approved, as we see in both the model codes for the U.S. and Canada and for New York as an example that I give just below.

The explanation given by engineers such as in the Sioux Chief report that I cite on this page is that air chamber type water hammer arresters "don't work" because the air in the chamber becomes absorbed into the building water supply, ultimately reducing the air pocket size and thus the effectiveness of the device in absorbing hydraulic shock caused in the water system by quick-closing valves.

The newer "manufactured" water hammer arresters use either a diaphragm or an internal piston that avoids losing the air charge.

These manufactured water hammer arresters look, externally, very much like their chamber type antecedents, but are designed to prevent he loss of the arrester's air charge.

Illustrated above and excerpted from our Sioux Chief citation, is an example of a "manufactured" or "mechanical" water hammer arrester.


2020 New York Plumbing Code - based on ICC/UPC

604.9 Water hammer.

The flow velocity of the water distribution system shall be controlled to reduce the possibility of 605.2 Lead content of water supply pipe and fittings.

Pipe installed where quick-closing valves are utilized.

Water-hammer arrestors shall be installed in accordance with the manufacturer’s instructions. Water-hammer arrestors shall conform to ASSE 1010.

Notice that while there is an ASSE standard that water hammer arrestors must meet, nothing in the plumbing code explicitly prohibits air chamber type arrestors, BUT notice as well this excerpt from the Canadian plumbing code:

"Since air chambers made from a piece of vertical pipe do not provide acceptable protection, pre-manufactured water hammer arresters are required to address this potential problem. 2.2.10.15. (1) Water Hammer Arresters: Water hammer arresters shall conform to ASSE 1010."


For our Canadian readers,

NATIONAL PLUMBING CODE OF CANADA 2010 (NPC/NRCC)

A·2.6.1.9.(1) Water Hammer Prevention:

Water hammer is a buildup of pressure in a length of horizontal or vertical pipe that occurs when a valve or faucet is closed suddenly.

The longer the pipe and the greater the water velocity, the greater the pressure exerted on the pipe, which can be many times the normal static water pressure and be sufficient to damage the piping system.

Since air chambers made from a piece of vertical pipe do not provide acceptable protection, pre-manufactured water hammer arresters are required to address this potential problem. 2.2.10.15.

(1) Water Hammer Arresters: Water hammer arresters shall conform to ASSE 1010.

Supporting Research also cited in more detauk above on this page

• ASSE (PLUMBING) 1010-2021 - Performance Requirements for Water Hammer Arresters STANDARD by American Society of Sanitary Engineering , 11/01/2021 - cited above on this page, and which unfortunately in the U.S. you can't read without paying without buying a copy for $45.00 U.S.
• Sioux Chief, WATER HAMMER CONTROL, Engineer Report [PDF] - above on this page
• Zurn, WATER HAMMER ARRSTORS - Zurn [PDF] - above on this page
  

Thank you for the discussion; working together makes us smarter.

Daniel.

On 2024-06-30 by Jan - Home irrigation system is causing water hammer in the house

My home sprinkler irrigation system (60psi) is causing a water hammer inside the house only when any zone selected to run first starts (doesn't matter which one of 9zones). The master valve started alone doesn't hammer, only when the first zone starts and last zone ends (but not as loudly).

Zone lines go above or below the manifolds but manifolds are at about the same level in the system and master valve is about 2 ft higher. . System is 30+ years old and didn't hammer in previous years.

Short of replacing the entire system, I would like to try a water hammer arrestor, but not sure where to put it. If inside the house, can it be mounted horizontally. The jolt spot is where the three-quarter inch supply T's to various feeds.

If on the irrigation system outside, is it Supply side or downstream side of the master valve. Can the arrestor be mounted on a T with an elbow or downward if outside on the irrigation system.

Reply by InspectApedia Publisher

@Jan,

From the article above we have

Here is what water hammer manufacturers say about water hammer arrestor size and location:

"The location should be at the piping serving the fixture(s) and normally between the last two fixtures. " - J.R. Smith Manufacturing Co. (Op. cit.)

"Water hammer arresters shall be specifically sized and have sufficient volume of air to dissipate the calculated kinetic energy generated by closing residential or commercial faucets or valves.

We reviewed the installation instructions for water hammer arrestors provided with this article: all say that their water hammer arrestor can be mounted in any position, including horizontal.

First try putting a water hammer device on the inlet to the master valve (the supply side).

If that doesn't help I would try putting a water hammer arrestor at the inlet to both the first and last sprinkler zones.

If that doesn't work we might need a more costly correction:

I've seen this problem before as have a number of our readers, both on sprinkler irrigation systems and on heating zones; in most cases we were able to fix the issue by changing to a slow-opening or slow-closing control valve.

Keep me posted.

Daniel

Followup by Jan

@InspectApedia Publisher, I have been thinking about where the water hammer occurs and the fact that I don't feel it in the PVC pipe at all. My main is 1 inch coming out of the basement floor and continues to be 1 inch going to the irrigation system.

At the point where it tees from the main to the irrigation system is also where the pipe steps down to 3/4 inch and goes to supply the rest of the house.

What I think is happening, is when the irrigation system turns on the pressure in the house line drops until the irrigation line is charged at which point the pressure again increases in the house supply line and I get the hammer.

I don't know if that should be a pressure tank to stabilize the pressure in the house or if I should put the water hammer arrestor on the house line since that is where the hammer is occurring.

I do not feel a jolt in the PVC irrigation line, only in the household three-quarter inch copper line where it branches in a few different directions to feed the bathrooms (half inch) kitchen sink [ half inch) and hot water tank (three-quarter inch).

Does this sound reasonable, since the hammer occurs when the sprinkler system charges the first zone and not when it shuts off. Insights/Suggestions/Recommendations would be appreciated.

Reply by InspectApedia Publisher - plastic piping may have less water hammer due to flexibility

@Jan,

Interesting additional detail, and helpful.

There are a couple of things to consider

First I'm not surprised that there's less water hammer effect where plastic piping is involved, both because it's flexible and possibly because it's a smaller diameter line with less water volume.

Second it's important to understand that water hammer happens because of a combination of water velocity and the sudden shut off or cessation of flow.

So you should be observing this water hammer sound when valves are closing. That should be diagnostic.

So when you're linking the sound to pressure equalization I have a little trouble following that.

Finally, I need to understand your water system. Except for some demand type water pumps that don't use an external water pressure tank, practically all pump driven water systems do use a pressure tank. And we often do add a water pressure tank on municipal systems.

On 2024-07-08 by Jan

@InspectApedia Publisher attached (above-left) is a diagram of how the main supply line comes into the house makes a tea about 4 feet off the floor with 1 inch copper going up another 4 feed and going through the outside wall to the PVC and master valve.

The other part of the tea steps down to a three-quarter inch line which goes up about 4 feet and first to the three-quarter inch line feeding the rest of the house and a half inch to a hose bib.

The irrigation line goes to a master valve about a foot outside the house and the first manifold is about 2 feet from the master valve. The mainline continues to two other manifolds as a 1 inch mainline.

Each of the manifolds connect to three Ridell three-quarter inch zone valves, the yard is large and the nine zones are fairly long on three-quarter inch line with what I call ratchet heads on most of them and one zone that is just pop-ups. Three zones go up/downhill.

The three-quarter inch copper line that continues in the house runs along the floor Joyce about 5 feet and then makes two 90° turns to zigzag through the joist and three-quarter inch line continues about another 10 feet to where it tees three-quarter inch to the hot water tank and half inch in numerous connecting tees to the sinks bathrooms and washing machine.

I call with the birds nest where Most of the half inch lines all branch at the three-quarter inch line to disperse throughout the house. the three-quarter inch Continues to the water heater at that location also.

When the irrigation program starts , there is an immediate water hammer when the first zone starts. If I run a manual program, not starting with zone one, whatever zone I start first does the same thing, it create a hammer.

It doesn't matter if the master valve is opened first in the manual cycle or after I have set the zones and then open the master.

The hammer is heard in the three-quarter inch copper line inside the house all along from the zigzag, to the birds nest.

When the irrigation program shuts off at the very end of the program (not after each valve), there is a sound of the system shutting off with a slight noise in the inside house pipes but not The boom like the hammer that wakes me up at 1 AM when the irrigation program starts, just more of a clunk like when I shut off the kitchen sink valve.

Hope this diagram helps you help me and I thank you for your persistence.

Followup by Jan

Update: got a washing machine water hammer arrestor that I rigged up on the half inch hose bib which is about as close as I can get to the 3/4" line without cutting pipes to test effects.

It cut the water hammer noise down by about 2/3 and minimal shaking so I will investigate putting a water hammer arrestor of appropriate size on 3/4" line as close as I can get to the irrigation line.

Reply by InspectApedia Publisher

@Jan,

That's helpful feedback.

Don't forget to look over your whole water supply piping to be sure that you've found all quick closing valves and check valves, and to be sure that each is working properly.

FWIW the usual advice from the water hammer arrester manufacturers is (e.g. Watts) you should install the device as close as possible to the source of the "shock" that's producing that slam-bang noise.

Usually that's a control valve.

So where are the valves that open and shut to control your irrigation system? Put the arrester there.

On 2024-09-02 by Jan - Water Hammer Problem Solved: earwigs in the check valve

Problem solved. Talked with Watts about backflow preventer Whole other story.

Former owner use a check valve.

While replacing that, also replacing anti siphon control valve with slow opening valve, I took apart the anti-siphon part and found earwigs lodged in the seat causing the anti siphon to leak.

New slow opening control valve without anti-siphon and backflow preventer to code solved the problem $$$$.

Reply by InspectApedia Publisher (mod)

@Jan,

Thank you so much for the followup - that will certainly help other readers so we really appreciate that you took the time to let us know what worked in your case.

In our articles on curing water hammer noise we had included a suggestion to change automatic valves (such as heating zone valves) to slow opening/closing valves where possible.

And we know that check valves can become leaky due to valve seat defects.

But I'd never considered that an anti-siphon valve might misbehave due to leaks due to clogging by earwigs.

Great going.

Daniel

Do I need a water hammer arrester on my ice maker?

If using Overnore [sic] plumbing why do you have to put a hammer on your ice maker - On 2022-08-13 by David -

Reply by InspectApedia-911 (mod)

@David,

If you are reading in a manufacturer's instructions the requirement for a water hammer arresting device on an ice maker I can but guess that the manufacturer has found that in some installations the water feed for the ice maker is controlled by a valve that causes water hammer problems.

Can I install the water arrestor system upside down?

I have a what it's two water hammer in wall system to install. I have pipes feeding down from attic can I install the system upside down ? On 2022-07-08 by Jim -

Reply by InspectApedia-911 (mod)

@Jim,

A review of the water hammer instructions included as PDF files in the article above show us that most of the newer water hammer arrester devices can be installed in any position.

Current or "newer" Water hammer arresters work in any position because they are constructed with an internal diaphragm or seal that keeps an air or gas charge separate from the water.

Watch out: However older simple chamber-type water hammer arresters not marked as complying with ASSE 1010 would not work installed in any position other than vertical, because their air charge would be lost into the water piping system.

When were water hammer arresters made mandatory?

What year were Water Hammer Arrestors mandatory for new homes? - On 2021-03-22 by Nicc44@comcast.net

Reply by danjoefriedman (mod)

@Nicc44@comcast.net,

Water hammer arrestors have not ever been mandatory on all water piping, but they've been around for many decades, and required close to quick-closing valves on water systems since at least 2018 where you'll see this iin model building codes,

A·2.6.1.9.(1) Water Hammer Prevention,

require a water hammer arrester installed as close as possible to "quick closing" valves - that is, at devices expected to cause a water hammer problem in buildings.

Can I adjust arrestors to get rid of banging?

I installed water hammer arrestors on my washing machine. They worked great for a couple years.

We just recently noticed low water pressure and changed our whole house water filter, which worked on the water pressure.

But now the pipes are banging again. Do I adjust the arrestors somehow? On 2020-01-01 by KP -

Reply by danjoefriedman (mod)

It's just an uninformed guess but it's possible that either you have an older type of chamber water hammer arrester OR debris has entered in clogged the water hammer arrestor and it needs to be replaced.

Water hammer arresters are not adjustable, BUT the device that you installed may not be working if

• It is too small for the DFU-rating of the piping circuit on which it's installed
• It is an older empty chamber type that would have lost its air charge.

On 2022-05-21 by bob - did you diagnose the trouble of banging pipes at washing machine?

@KP, you figure it out?

Reply by InspectApedia-911 (mod)

@bob,

We didn't hear an update from KP, but it would have made sense to replace the water hammer arrestors as the first step.

The result would be diagnostic.

Generally water hammer is a velocity problem although occasionally similar noises are produced by a short cycling water pump.

...

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Citations & References

In addition to any citations in the article above, a full list is available on request.