Water Hammer Plumbing Noise FAQs

Diagnostic questions help find & fix the causes water hammer or shock - noisy pipes & fixtures

Banging Hammering Water Pipe Noise FAQs

Banging noise when closing off hot water taps

I have just had a combo boiler fitted, didn't gave a combo boiler before this.

Now I have problem with banging popes when closing off hot tops and after cistern has filled up.

Plumber wants to fit an arrester near stop cock. Cost is about £200. is this the best thing to cure the problem. On 2017-12-14 by Sandra Dawson -

Reply by (mod) - cost of water hammer arresters sold in the UK

Indeed an arrester can stop banging pipes, though that cost *might* be a bit steep.

A Sioux Chief water arrester sold in the UK by Wickes is under £20 - but perhaps your plumber feels you need a larger device or that access to piping is going to require some costly labour.

Plumber charges vary widely depending on where you live but typically a plumber charges around £75 per hour.

So the cost estimate of £200 might be based on the plumber's estimate of 2 hours labour and the remainder in parts.

OR the plumber may also have a fee for travel.

Is it normal for there to be a water hammer noise for 15 minutes after turning water back on?

My husband shut off the valve to a toilet for a minor repair in the tank (something like a float) and when he turned the valve back on he heard water hammer and immediately shut the valve back off.

I have read it is normal for this noise for the first 15 minutes, but he says we need to call an expert because it will cause damage.

Oour home was built in 2004 but is a concrete slab, but should have the regulators in them. he knows 0% about plumbing, but I want to try to simply turn the valve back on to the toilet. what should we do? thanks! On 2017-12-12 by Isabelle -

Reply by (mod) - NO

Isabelle

No it's not normal to hear water hammer for 15 minutes after working on the toilet.

More likely the problem was the specific velocity with which water was entering the toilet. Try opening the valve all the way - if the noise starts in that position try closing the valve a bit - and so on.

Do we need a new well to fix water hammer banging hammering noise?

We hear a loud hammering noise after flushing toilet or using water inside house. is this doing damage? Can it be fixed without getting a new well? On 2017-08-15 by Meandpat -

Reply by (mod) - NO

Water hammer can do damage, causing leaks, burst pipes, damaged valves, and more subtly but

Banging water hammer when water is turned both on and off - Australia

I've read some of the water hammer comments and the noise seems to arise when a tap is turned off.

However the water noise in my apartment in a 3 level complex consists of a loud "bang" (water turned on?)and then the sound of water rushing for about 5 seconds and then a loud bang when it stops.

There's an interval of about 15 mins or more and it happens again.I thought it was the water gardening pipe that runs under my unit but apparently that pipe wasn't being used at the time in question (3 a.m).

I'm aware water hammer is caused by, say, turning a tap off or a washing machine stopping water flow when its full (water stopped) but this noise (first bang) occurs at the start when the water is apparently turned on.

My Building Executive Committee said the noise could be caused by tenants turning on and off their "over pressured taps" or from a dishwasher or washing machine. I'm glad you said a sound recorder could easily record the noise because I'm going to get one and try to get to the bottom of this. Any comment? Thanks On 2016-06-19 by middle Australia -

Reply by (mod) -

It sounds like water hammer to me, and a committee blaming the victim not the cause; record the sounds; consider installing water hammer arrestors.

There are both water-hammer reducing devices that can be installed on the piping near the valve and slower-closing valves that can be swapped in if needed.

I agree it's important to fix this as water hammer can cause damage, leaks, even unsafe conditions (as it can damage a relief valve).

Please see the suggestions at WATER HAMMER NOISE DIAGNOSE & CURE

Water pipes shake and bang near end of water tank re-fill after using water: related to heat pump sharing same well?

I have a domestic well and a ground-water sourced heat pump that operates off the same well. I have pressure tank with 15 gallon draw and 44 gallon capacity.

Only recently, when water has been running for several minutes and then stops (like when the heat pump has run a cycle and stops drawing water), the well pump fills the pressure tank, when the pressure is almost to the right level, the pipes (plastic) begin to shake and produce loud sound.

The sound last for 15 to 60 seconds, and seems to stop when the pressure tank reaches the shut off setting.

Tank is set to 20/40 psi now, when sounds started it was 40/60 psi. The adjustment didn't help. I've now had two plumbers here a total of six times over two days and they can't find the I ssue. All they have managed to do is mask the sounds with foam pipe I nsulators, foam under the pressure tank, etc. - not addressing the actual cause.

They told me pressure tank operates fine, well pump is operating great too. Thanks for any suggestions, we are not sleeping well for a couple weeks now and need a solution. Appreciate the help! On 2018-03-01 by ChadF -

Reply by (mod) - domestic well and a ground-water sourced heat pump seems to cause noises

Is the pump in the well?

is the pump relay switch chattering?

is the pump having trouble reaching the cut-off pressure?

We may want to pursue those questions and think further before just adding water hammer control devices.

Recapping the key I ssue

When the pressure is almost to the right level, the pipes (plastic) begin to shake and produce loud sound. The sound last for 15 to 60 seconds, and seems to stop when the pressure tank reaches the shut off setting. Tank is set to 20/40 psi now, when sounds started it was 40/60 psi.

I might experiment by closing valves to the ground-sourced heat pump to confirm that the problem does not occur except when the heat pump is online.

When I have seen this shutoff chatter at a well pump it's often been traced to a chattering check valve or control valve that's operating just enough to destabilize the pressure control switch near the cutoff pressure.

by ChadF

Any further thoughts on this? Still having the I ssue. Plumbers have now replaced the well pump, which didn't work. Lucky they said they wouldn't charge me if it didn't fix the I ssue. We are literally going crazy having to have plumber after plumber I here and never getting anywhere. Really need some help folks. Thanks.

The pump relay switch doesn't chatter at all either. Thanks for the help!

The pump is in the well. Plumbers have told me the pump is 1/2 HP and is likely barely large enough, should have been 3/4 HP.

As far as pump having trouble reaching cut-off pressure, the sound happened when the cut-off was set to 60 PSI and was I dentical when reduced to 40 PSI. The pump's amp draw was too high at the higher cut-off but was humming perfectly at the lower. I'm no expert, but it doesn't seem like it's having trouble reaching the cut-off pressure.

by (mod) - noise occurs with the heat pump online and with it offline.

If the heat pump operation is not affecting the presence or absence of a noise, determined by shutting down the heat pump system and observing that the noise recurs, I'd look elsewhere for its source.

by ChadF

The noise occurs with the heat pump online and with it offline. After the plumbers replaced the pump, which had a built in check valve, the noise still occurs, but changed to a more random pattern.

it now occurs I ntermittently, sometimes while the heat pump is running, sometimes after the shower runs, or after/while the washing machine fills. No rhyme or reason.

Could debris become clogged in the manabloc and cause something like this? is it safe to blow air through the manabloc? Running out of options.

Water Hammer Damage to Water Pipes Q&A

Will water pressure surges weaken pipe?

Is it true that repeated high surges of water pressure can weaken pipe over time?

If so, would this mean one could extend the life of discharge plumbing pipes by moderating the flow of waste water? On 2017-06-30 by Scott

Reply by (mod) - Surges of water pressure can weaken pipe but commonly water hammer causes leaks; Here's supporting Research

Great question, Scott.

My gut feel is no if you're talking about typical residential water piping materials, and if you're talking about the normal ranges of residential water pressure systems, such as between about 20 psi and 70 psi, and if we ignore the connections - it's a connection that is more likely to wiggle, weaken and come loose in response to water hammer.

Watch out: while pressure surges in the range I mentioned should be harmless, but at higher velocity, yes pipes can be damaged as we explain

at HIGH VELOCITY WATER in PIPES - SCRUBBING DAMAGE

And also that is not the case for actual banging pipes caused by water hammer.

That can lead to plumbing leaks and even unsafe relief valve leaks.

We discuss leaks and damage from water hammer at WATER LEAKS & PIPE / VALVE DAMAGE FROM WATER HAMMER

There is some expert material failure research that digs more carefully into your question, as well as some theoretical modeling such as

• Schmitt, C., G. Pluvinage, E. HADJ‐TAIEB, and R. Akid. "Water pipeline failure due to water hammer effects." Fatigue & Fracture of Engineering Materials & Structures 29, no. 12 (2006): 1075-1082.
  Abstract:
  
  A numerical model has been established in order to simulate the propagation of pressure waves in water networks. The present model formulation is based on a system of partial hyperbolic differential equations. This system has been solved via the characteristics method.
  
  The current model provides the necessary data and the necessary damping of water hammer waves, taking into account the structure of the pipe network and the pressure loss.
  
  The numerical algorithm estimates the maximum pressure values resulting from the water hammer when closing valves in the network and consequently, the maximum stresses in the pipes have been calculated.
  
  in the case of simultaneous closing of several valves, the over pressure can exceed the admissible pressure. in this case, the severity of a defect such as a corrosion crater (pit) has been estimated by computing a safety factor for the stress distribution at the defect tip.
  
  This allows the applied notch stress I ntensity factor to be obtained. To investigate the defect geometry effects, semi-spherical and semi-elliptical defects are deemed to exist in up to one-half of the thickness of the pipe wall.
  
  The outcomes have been I ntroduced into the structural I ntegrity assessment procedure (SINTAP) failure diagram assessment (FAD) in order to obtain the safety factor value. Conventionally, it is considered that a failure hazard exists if this safety factor is less than two.
• Halliwell, A. R. "Velocity of a water-hammer wave in an elastic pipe." Journal of the Hydraulics Division, 1963, Vol. 89, I ssue 4, Pg. 1-21
  Abstract:
  
  The general expression for the velocity of a water-hammer wave through a fluid in an elastic pipeline is evaluated.
  
  This result is applied to the following common practical cases: A rigid pipeline; thick-walled and thin-walled elastic pipelines with various longitudinal constraints; rock tunnels; and tunnels having a steel, or concrete, or steel and concrete lining.
  
  The results obtained are compared with those given in several standard reference books.
  
  it is shown that certain errors do exist, and considerable confusion does arise with these texts due to the fact that the assumptions made by the authors have not been clearly stated.
  
  Most of the confusion and errors in the texts are concerned with the effect of the external constraints or of Poisson's ratio, and the error I nvolved I s, in general, small (less than 10%).
  
  Nevertheless, this error may be I mportant, and textbooks should make quite clear any assumptions made in deriving their results.
• Lahlou, Zacharia Michael. "Water hammer." Water Encyclopedia (2001).

Reviewing those and other sources suggest that some pipes could fail along the pipe length from water hammer.

Note: Water hammer is not going to happen in drain pipes carrying wastewater - as expressed in your question - but rather in supply pipes that are under pressure.

Do Water Hammer Suppressors go Bad OR get Clogged up and Stop Working?

Do hammer suppressors go bad OR do they get clogged up and stop working because of that? On 2017-04-03 by R.S. - AUTHOR:R.S.

Reply by (mod) - yes and no

A water hammer arrestor can be damaged by mis-handling during Installation, as Watts points out in their Installation guide.

But typical water hammer arrestor design includes a sealed chamber that should not clog nor fail by leakage.

If the water hammer arrestor never worked satisfactorily I suspect that it was installed in the wrong location or that the wrong size was selected.

Water hammer an occur on a plumbing system as a "new" I ssue also if / when any valve is changed to a different type, such as a fast-closing zone valve on a heating boiler.

Watch out: however some older design water hammer arrestors that don't keep their air charge separate from the water itself can stop working as their air becomes absorbed into the building water supply. That should't happen with more modern water hammer arrestor devices as those do keep their water and air separated.

Other Sources of "Water Hammer" Noise FAQs

Find Source of Random Banging Sounds from Sink, I ndependent of water use - not water hammer

The past 4 months I've been getting random banging sounds from under the sink in the ensuite. it can happen day/night, at times where no water has been used in the house for hours.

The sound comes from somewhere along the pipe in the wall. The house was built in 2009.

Plumbers have come out, it's not water hammer although he drain all water from all taps in the entire house (heard the sound 4 hours later).

I've turned off the main water line at night and have still heard I t. There is no leak, water stains, etc. The last plumber said it may have to do with heating ducts causing expansion and contraction?

(Not sure what the connection is with that, there is a heating vent in each bathroom) The sound is definitely coming from under the sink and it carries over to the pipe under the sink on the other side of the wall in the other bathroom.

I cannot find any pattern as to what triggers I (i.e. it's not after a shower or when the toilet has been flushed, etc.). Any help would be greatly appreciated as it's extremely annoying. I even hear it when I'm on the main floor as the sound comes down through the ceiling. Sometimes I don't hear it all day other times I hear it 10 times in one hour. On 2021-01-19 by Denise

Denise

Indeed we need more sound recording and tracking work at your house; sounds caused by an event in one location such as a heating system can be picked up and transmitted by nearby materials, so ducts can conduct piping noises and vice versa.

NOISE SOURCE LOCATION - LOG FILES

and other suggestions are

at NOISE / SOUND DIAGNOSIS & CURE

by Denise

I have poured through the resources here and have found nothing that comes close to what I'm experiencing.

I'm ready to call someone in to cut into the wall in the upper level as the sound is so unpredictable and at times can be very loud. Attached is a summary of just today and late last night....interested if you can see anything that I'm missing.

Thank you. I will look at those links later today and can perhaps upload audio. The trouble I s, the sound isn't constant or always repetitive, so it's hard to know when I'll hear it again after the I nitial bang sound.

it can also occur when the furnace hasn't cycled for hours so it's hard to pinpoint if that is the problem or not. I'll give you an update....

by (mod) - Trouble finding source of banging pipes & alternatives to water hammer noise

Consider that the noise you hear may not be water hammer, but other sources of banging noises in buildings such as expanding metal duct work or HVAC noises or other thermal expansion and contraction of materials.

See these t diagnostic articles

• BANGING HEATING PIPES RADIATORS
• BANGING BOOMING NOISE DIAGNOSIS & CURE
• SOUND EVENT LOG 
• WATER HAMMER DIAGNOSIS
• WATER HAMMER CURES

For a confounded noise track down such as the situation you describe, even though it's difficult, the most-profitable course of action is a combination of

- locating the noise source by amplitude (instruments can help)

- locating noise sources by noting what equipment is running or not running

- relating noise to exterior conditions: temperature, sunlight, weather, air movement, occupancy, etc.

For that the noise log I cited earlier and that you've attempted (example above) can help

by Denise - It's definitely not water hammer: Noise log data example given below

It's definitely not water hammer as the first plumber ruled that out. The house was built 2009. I did look at the links you shared but nothing jumped out. If it's due ducts expansion, how could it be that the banging occurs when I haven't used the furnace for 8 hours?

Hi,
Attached is a summary. You will need to put together the pages horizontally, not vertically.

The main source of noise is in the wall between the 2 bathrooms (approx 15' in length) so I'm not too sure I'd be able to pinpoint it much further with a mechanical stethoscope unless I cut into the drywall.

Denise

by (mod) - Example noise log helps track down banging pipe noise

If you've pinpointed the noise to a specific wall it may be time to take a look into the wall: by cuts or a boresope; or you might want to bring an experienced building Inspector or sound engineer onsite. We need to relate the apparent noise sources you suspect that seem in your log to be disparate.

We assembled your Noise Log data vertically simply so that it could be read by most viewers.

[Click to enlarge any image]

Night time water hammer knocking noises - caused by watering system that runs at night?

Loud knocks between 2am and 4|30am. NO I nside or outside water is running at that time.

Our home is on a water supply with 300 other homes. The water supply company has 3 wells in our community.

During the day there is no knocking, thumping, sputtering of any kind. THe noise is on the side of the house with the meter.

is pressure from water supply causing this when someone's I rrigation, or swimming pool turns on, or flush of toilet from neighbor between the hours of 2am and 4:30am? On 2016-10-16 by Bill

Reply by (mod) - check to see what other water-using system or equipment is running

Bill, if you're sure this is a piping noise, yes the watering system could be the cause. See if the watering timer setting corresponds with the noise.

For example it's common for water treatment equipment suchg as a water softener to have its regeneration time set for the middle of the night when we don't expect anyone to be using water.

Water Hammer / Plumbing Noise: Neighbor Complaint FAQs

Annoying plumbing sounds (shower) from townhouse neighbor

I live in a townhouse with common walls, after my neighbour renovated his bathroom I can now hear when he uses the shower, which is annoying and due to his shift work is in the very early hours of the morning.

it's a loud, constant white noise type of sound rather than a hammer.

Your advice as to the cause would be greatly appreciated. On 2021-01-14 by Steve -

- by (mod) -

Steve

I doubt that anyone can give a reliable exact explanation of the noise that you were hearing now from simply a brief text note.

But it's possible that you were simply hearing normal plumbing noises that would be better I solated if there were I nsulation in the common wall between your two living spaces.

That may be something you can add for example by pumping or blowing in foam or a similar sound deadening material. it won't be perfect because the wall framing will still conduct some sound but it should reduce the I ssue.

See SOUND CONTROL in BUILDINGS

by Steve

Ok thank you for your reply, much appreciated.

Water Hammer "Tapping" Noise FAQs

Tapping noise when water is running

Recently added a circulating line and pump to my water heater. As a precaution, I also added an expansion air tank.

I am on city water, so I have great dependable water pressure. I do have an I rrigation system, but that is closed off because it is winter.

Since the install of my pump, I am experiencing a tapping when a faucet is open an water flowing.

I have I colated the noise to be a backflow valve, which was previously in place, but now is making a noise as if it were opening znd shutting constantly while water is flowing....approximately every "second". Could the circulation pump cause this? Could the expansion tank cause this? These are my only two main variables. On 2020-12-24 by Roland

Reply by (mod) -

Roland

Indeed that sound could be coming from your pump. I've encountered exactly that problem in a water system that we recently Installed. it depends on the type of pump and where it is Installed. Maybe you could tell me more about that.

Water heater source of banging noises ?

My water heater makes a low knocking noise

What is causing my water pipes to randomly have a low knocking noise and I just put in a new water heater about a week ago but this was going on before I put the new water heater I n? On 2020-12-23 by Tony

Reply by (mod)

That's not a water hammer problem but more-likely a water heater banging noise.

See our detailed diagnosis and repair advice for noisy water heaters given

at BANGING WATER HEATER

Water Meter / Pressure Regulator as Cause if Water Hammer FAQs

Water Meter Might be a Water Hammer Noise Source?

I have a somewhat different water pipe noise problem.

A couple weeks ago, I noticed noise -- thump, thump, thump, -- about 2-3 times per second and continuing for about a minute coming from the water line in my garage.

The line, (PEX pipe) installed 2 years ago to replace the original line that was leaking, runs from a meter by the street, underground and then up through a hole in the garage floor to the ceiling and finally around two walls to the shutoff and pressure regulator next to the hot water tank.

The noise is not very loud. I can usually hear it only when I'm in the garage. But I can feel the pipe shaking when thumping. I'll guess it occurs a few times each day.

My plumber I nitially said it was caused by a failing regulator but then he found the thermal expansion tank was full of water. He attached a pressure gage to a spigot and told me to not run water until he returned in an hour with a new tank. The pressure stayed constant (~60 psi) until he returned so he replaced the tank and not the regulator.

Next day I heard the thumping again. The plumber convinced me to also replace my 16 year old Rheem water heater although in my experience, Rheem tanks last over 20 years.

But the following day and subsequently, I've heard the thumping again. Twice when this was occurring, I checked the water meter to verify no water was running. Once I went in the house and opened a faucet but the thumping did not stop right away.

The house is in Prescott, AZ and was built in 2004. The supply pressure is rather high -- 110 psi and about half of the water lines in my development have failed but I believe the failure is due to I mproper filling of the trenches with chunks of basalt rock rather than the proper sand bedding and shade fill.

The replacement line was properly installed and Inspected by the city. Another nearby development is at the same altitude, thus likely similar pressure but homeowners there do not report water line failures. Several neighbors I've asked do not report not hearing similar noises.

What to do next? - 2020-11-30 by Fred O

by (mod) - no, but check for clandestine water use

if there were really no water movement through pipes then what might cause pipe "noise" in the first place?

Possibly some other, even outside, mechanical noise source that's being picked up and transmitted by the piping

or

a local pressure booster pump

or there is a leak somewhere that's not been found. Don't forget to check for water that's running in secret, such as a running toilet.

I F water is flowing in the home but the water meter isn't registering that water use then the meter is probably damaged and that might Indeed be the noise source.

It might be Interesting to use a mechanic's stethoscope on the water pipe at several locations when you are hearing the mystery noise

by Fred O - I suspect the water meter is the noise source

RE: "It might be Interesting to use a mechanic's stethoscope on the water pipe at several locations when you are hearing the mystery noise".

Thanks again for your advice. I can feel the pipe shaking slightly where the pipe is exposed. Also see below.

Today, a new development. Rather than "thump, thump, thump" at a moderate volume, we heard "tap, tap, tap" at faster cadence and lower volume. We could also feel the tapping on the pipe but it was not as prominent as earlier.

I went out to the water meter, which is in a box just below ground next to the street and I could feel the tapping on the meter. Again, no water flowing and the spinner on the meter did not move. A bit later, the thumping returned, louder than the tapping but I think at lower volume than the thumping before.

I now suspect the meter. A week ago, I called the Prescott building Inspection dept. and left a message They have not called back. I plan to leave an email msg.

RE: "If there were really no water movement through pipes then what might cause pipe "noise" in the first place?"

A couple times I've looked at the water meter when the pipe was thumping but did not see any movement. Once, I noted the position of the spinner and saw it in the same spot 30 minutes later.

"Possibly some other, even outside, mechanical noise source that's being picked up and transmitted by the piping or a local pressure booster pump or there is a leak somewhere that's not been found."

I I ntend to try feeling the meter for vibration next time I hear the noise. But it occurs only occasionally. Only pump is the hot water recirculator and that's on a count-down timer that I installed myself. As for leaks, the water bill has not been elevated.

Tis a puzzlement. Thanks for your thoughts. I've asked my city building dept. but they have not answered my query.

Water hammer noises traced to heating radiators

My radiators are banging so loud that a pipe in the basement popped. I sealed it temporarily with a screw. I located a leak , due to the radiator not being tightened enough.

One of the small pressure relief valves in the basement is leaking water at the part where only steam is supposed to come out. I am so done. help me please. On 2016-03-21 by Antoine

...

I live in Plymouth Wisconsin. Are you aware of, or can you direct me to, a website/phone number which will help address violent radiator hammer sounds in my building apartment? I have approached the building manager and landlord to address/repair the problem and they have been dismissive.

Do I have any recourse other than treating this as tenant vs. landlord legal matter? Thank you. Sincerely, Robert F bobbyofallon@gmail.com - On 2015-11-13 by Robert F

by (mod) : More likely it's banging heating pipes from other causes

Sure Antoine and Robert F

See BANGING HEATING PIPES RADIATORS 

to diagnose and repair this trouble. Usuallly the problem in your case is condensate is not returning.

Watch out: Antoine, a leaking pressure relief valve is unsafe. Details are at RELIEF VALVE LEAKS

Water Hammer Arrestor Location FAQs

installed water hammer arrestor at the water pressure tank

I installed my water arrester at the pressurize tank. Our water source is an overhead tank, water pump is located lower than the source and check valve next and pressurize tank after.

But hammering still exists and is annoying every time the pressure switch shut-off. Please give me more details location of tapping the said device. thanks 2016-01-21 by robert

by (mod) - wrong location

Robert

it may be that the Installation location you chose is not the best - see WATER HAMMER NOISE DIAGNOSE & CURE about locating the water hammer arrestor near highest fixture.

Water Hammer Damage to Check Valves or to Pressure Relief Valves Q&A

Septic pump check valve noise / damage from water hammer?

Water-hammering noise from check valve in septic sump pump…solution? 5/29/14 Naaj 

Reply: the check valve won't cause water hammer but water hammer can damage the check valve

Check that you don't have multiple check valves installed on the same piping system- required in some deep well installations but often not-recommended otherwise.

If there is only one then you're ok on that score but

Watch out: water hammer can damage a check valve on your well system and so cause loss of pump prime: you'll want to install an anti-water hammer noise product such as those discussed

at WATER HAMMER NOISE DIAGNOSE & CURE

Water hammer related to loss of pump prime, water pressure control switch?

Replaced pressure tank with bigger capacity tank. Water now loses prime every so often. Could it be the preassure switch or backflow valve got debris in I t? (Apr 15, 2015) lose prime

Reply: Yes, water hammer can damage a check valve on your water pump system and that in turn loses pump prime

Lose

That's a smart guess, particularly if your water pump uses an I nternal check valve or if such a valve is installed at the pump, else I suspect a failing foot valve.

I 'm not clear why this is a water hammer noise question. But if you're hearing repeated water hammering or banging when the pump turns on or off the problem could be at the water pressure control switch or at the water pressure tank or even the pump.

A good example is a clogged water filter at the tank that causes rapid pump cycling at the end of a pump-on cycle.

See these two diagnosis and repair articles

WATER PUMP SHORT CYCLING - pump turns on & off too frequently

WATER PUMP PRESSURE CONTROL SWITCH CHATTER

Will the Temperature & Pressure relief valve protect the hot water tank against water hammer damage?

Will the T&P valve protect the tank against breaking from excessive water hammer? - Watts

Reply: no and Watch out: water hammer can make a water heater or boiler relief valve unsafe

An "excessive" water hammer is an abnormal but momentary condition that causes a very brief surge in water system pressure.

The pressure-relief component of a temperature and pressure relief valve can only discharge a verly limited amount of the surged pressure during the moment of shock of the water hammer event, possibly none.

But if water hammer is causing frequent opening of the temperature and pressure relief valve there may also be a risk that the frequent passage of hot water through the valve deposits scale that eventually accumulates to a level at which it prevents safe reliable operation of the valve in an emergency.

Watch out: leaks at tempeature/pressure relief valves can ultimately clog with mineral deposits left by the passage of hot water; such a valve clog can prevent the operation of this important safety device and so could lead to a dangerous BLEVE EXPLOSION

And the fact that temperatures I nside the hot water storage tank are elevated above cold water temperatures makes no difference - with the exception of this warnin:

Watch out: if the hot water tank is in an abnormal overheated condition, that is water in the tank has become superheated above I ts atmospheric boiling point water hammer could actually lead to a water heater tank explosion. According to Watts Regulator Company, "Water hammer conditions are believed to be a partial factor in starting off an explosion of overheated tanks besides "pressure heat rupture". [10] paraphrased.

Intermittent banging when hot water turns on - due to pressure relief valve?

My water heater was got replaced 6 months ago. Since then whenever the hot water gets turned on, there is a intermittent bang sound occurs. it only happens when hot water turns on.

Just wondering if this is related to the pressure relief valve. Any idea? Thanks.On 2016-03-24 by Will -

Reply by (mod)

The pressure relief valve won't itself cause water hammer, but as I said earlier it could leak dye to water hammer.

Banging noises can come from there and might be heard after running hot water as the water heater turns on and a combination of heat and scale in the water heater cause it to make banging, popping sounds.

See WATER HEATER NOISE DIAGNOSIS, CURE

IF there are no banging noises at the water heater, then heck out the live link at

Continue reading at WATER HAMMER NOISE DIAGNOSE & CURE

For water hammer explanation and cures. You'll see its probably a water velocity issue, fixed by adding a water hammer prevention device or a slow closing water valve.

Other Valves That Can Cause Water Hammer Noise

Ball cock in the water tank in loft causing water hammer?

Can it be the ball cock in the water tank in loft causeing water hammer? (Oct 18, 2014) mr conner

Reply: Possibly

Water hammer is an effect of the velocity of movement in water pipes along with pipe dimensions and layout, combined with a sudden STOP! of water flow.

Any valve can "cause" the effect to be heard. Some plumbers install slow closing valves to reduce the problem but you'll read other solutions in the article above.

Banging pipes at end of water softener cycle?

At my home (Cypress Texas), we hear water hammer noise at the end of water softner regeneration cycle. There was no water hammer prior to installation of water softner.

I brought in the water softner Installer and could not figure out why and told may be water pressure is high when the regeneration cycle occurs. He changed regeneration cycle time from night to afternoon and we still have water hammer.

The regeneration cycle is after 10 days and lasts for 1 hr 45 minutes. Did water softner not installed properly? The house was built in late 2010 (by village builders a subsidiary of Lennar Homes). We had water water softner installed in 9/2011.

We purchased this new home and moved in April 2011. I called in a plumber and he was not much help. I am considering to contact the plumbing company (New Tex) who did the original plumbing in the home. May be they can figure out and fix this problem. Any guidance you have. Thanks (Nov 18, 2014) A Kang

Reply: yes when the water softener internal valve closes that might cause water hammer

AK

Ask about Installing either an appropriate water hammer control device (described in the article above) or a slow-closing control valve on the supply to the water softener.

Why does water hammer noise suddenly appear in a building?

Why would my plumbing suddenly start making water hammer bangs when it never did before? Nothing changed in my plumbing or any appliances, yet I start hearing significant water hammer. Yesterday, all was quite as it has been for years, then today I hear water hammer. Any I deas? (Apr 12, 2015) Carl C

Reply:

Great question, Carl. I can speculate that

- water pressure may have I ncreased at the source

- a pipe or fixture has come loose

- a control valve has been opened or closed to a different extent than previously

As water hammer is related in large part to velocity of flow and sudden stopping, a change in a valve can be enough. Certainly something has changed so let's start with that assumption.

Water Hammer Noises vs Pump or Water Tank

Water hammer noise after Installing a booster pump for water pressure

I've recently replaced a booster pump in my residence.

This new pump switches on I mmediately 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 I dea where to install I t. 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 Andy s

Reply:

Interesting; 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 I ncoming 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.

Here is what water hammer manufacturers say

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

"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." Sioux Chief Manufacturing Co.