Hot Water Heater Noise FAQs

Banging Water Heater Noise FAQs

Banging water heater when outdoor temperatures drop

Question: I live in Houston Texas. I have two water heaters in the attic and every time the outside temp drops below 45 degrees the heater makes loud banging noise that is loud enough in the room below the attic to wake you up in the middle of the night.

The noise continues for some time but the heater operates quietly in warmer weather above 45 degrees roughly. What is going on?

This has been going on for few years but no one is able to identify the problem mostly because the noise is only at night or early mornings when it is still cold and by the time a repairman comes its normal and quiet. On 2014-04-15 by Nancy -

by (mod) -

Nancy often we notice noises more easily at night; and in cold conditions, given that the heater is in a cold space (unheated attic), the heater may be working longer and harder to heat water.

Those conditions combined with scale formation could lead to banging noises.

It should be easy enough to drain the water heater and check for scale in the heater bottom - that's where I'd start.

Cures for Water Heater Scale

1. WATER HEATER SCALE DE-LIMING PROCEDURE exactly how to get rid of water heater scale, a common cause of water heater noises.
2. WATER HEATER SCALE PREVENTION - how to avoid scale formation in water heaters
   

Loud BANG at water heater start-up

We have two small water heaters upstairs to serve the upper part of the house.

Occasionally we hear a very loud BANG (just one) as if someone dropped a very large encyclopedia on the hardwood floor.

Could this be from the water heaters? (Apr 24, 2015) Jeff

Reply:

Yes Jeff, though the bang is more likely if your water heater is gas or oil fired.

Banging might be just due to scale in the heater, or something more dangerous if the noise is from an oil or gas burner.

Watch out: Such BANGS may be quite dangerous - please see the discussion about water heater startup bangs and explosion sounds in WATER HEATER NOISE

Let me know if any of that leaves you with more questions.

Loud BANG! at our water heater, now house pressure has dropped

I took a shower this morning and while I was getting ready I heard a loud bang from my garage where my water heater ids located.

Now the water pressure in my house has dropped considerably. Are these related? On 2014-03-31 by Valerie F -

by (mod) -

Valerie,

Possibly. Take a look at the water heater in the garage. Is it visibly damaged? If it is a fuel burning heater (as opposed to electric) there are additional hazards if it is not properly vented or if there has been a fuel or gas leak.

If there is ANY doubt about the safety of the heater turn it OFF or turn its power and fuel supply off if you can safely do so. If you can't you'd need to go outside and call emergency services like 911.

Apology for being so cautious but what else can one do when discussing this matter just by text than to be careful.

by Valerie

Thank you for your response, Dan. There is no sign of any damage, just lower water pressure. I will call a plumber tomorrow.

by (mod) -

Great thanks for the follow-up. It makes sense to be safe first. Keep us posted as what you learn will surely help other readers.

DF

Rate of hot water use may affect water heater banging popping noise?

Gas water heater makes the popping sound that is typical of sediment build up.

However, it only makes the sound when the bathtub faucet is turned on (the bathtub faucet water pressure also drops).

Eight other faucets in the house and none of them cause the same noise. Any help would be appreciated. On 2019-02-13 by Kevin

Reply by (mod) -

Just a guess it could be related to the rate of hot water use.

When more hot water has been consumed or when it's being consumed at a faster rate, more cold water is entering the water heater in a shorter period of time.

In my experience, that yields a longer water heater "on" cycle and sometimes, particularly with gas-fired or oil-fired water heaters, a hotter water heater bottom (over the burner) that in turn leads to louder popping and banging sounds, especially if the bottom has a thick coating of mineral scale.

 

Noisy attic water tank sounds like pipes banging together & toilet overflows

My water tank in the attic is so noisy, my pipes sound like there banging together plus the toilet cistern is constantly overflowing! So frustrating. - 9/12/12

Reply:

Jim:

Often a very noisy water heater that bangs and clanks as it's heating up is due to scale formation. That might be worth checking out, along with how well the water pipes are actually secured.

I don't think that a water heater is going to have much to do with a toilet cistern problem - more likely that's a problem with the fill control valve in the toilet.

Take a look at TOILET REPAIR GUIDE.

 

Anonymous reader blames thermocouple for water heater noises?

So many of the threads i have been reading are SO VERY WRONG. In instances of a single loud BANG or explosion type sound 99.9% of the time the thermal couple needs to be adjusted closer or further from burner depending on if you see a flame or not. Move thermal couple closer if no flame comes out of flu when you hear the bang and further if does. 2015/12/10 Anonymous

Reply: watch out for dangerous, incorrect advice.

Thank you for your anonymous opinion, but

Watch out: here you may be giving very dangerous advice - that could kill someone.

Rumbling banging water heaters - continuous noise when the burner is on - are most often traced to scale deposits.

But

Watch out: A single loud bang at start-up is very dangerous if it is caused by the ignition of unburned fuel, whether gas or oil. Such heaters should be shut off and then repaired by a trained service technician.

The thermocouple is a safety device that closes a gas valve if a safe flame is not maintained. I agree that misplaced thermocouples may prevent a gas burner from staying on but I would not expect that to cause explosions.

Readers whose water heaters cause a single BANG when the heater temperature goes from cold to hot - for example if the heater has been left off for a time or if you used all of the hot water in the heater, then stopped running water while the heater re-heated, should investigate water hammer - search InspectApedia for that term.

You might need an expansion tank on your hot water system. If you're having this problem also look for water hammer induced dripping at relief valves. That's a dangerous condition too as repeated dripping can ultimately clog a valve leaving the water heater unprotected and thus risking a BLEVE explosion.

Separately: sometimes there is a single loud bang type noise at forced air heating furnaces - occurring when ductwork is heated and expands.

Question: banging water heater noise

I should say sounds like when you hit an empty hollow water heater very hard because the noise is so loud that I can hear it upstairs far from the garage where it is situated. Thank you.

Hello, great article! But I still don’t know what is causing my water heater to make noise. We installed a new gas water heater in March 2017. Everything was fine until November when I noticed every time we use hot water, about 1 1/2 minutes later, the water heater itself gives out

a single banging noise that sounds exactly like when u hit a metal spoon against the water heater, almost gong-like. Just once.

My friends said it’s the cold weather causing it to expand. But I’m still worried. I live in Southern California, the weather has been colder than normal. Can you please help? Thank you. On 2018-02-21 by Teresa

Reply:

Teresa

It would help if you could tell me what kind of water heater this is, that is electric gas or oil fired. But in any case do you think it's possible that we're hearing a thermal expansion noise?

Very often when metal components such as a flue vent connector on a fuel fired water heater, or even the metal case of an electric water heater, as the heater or other component warms up or cools down we may hear one or more single loud banging like noises.

If the sound occurs when you turn water on or off then you want to search inspectapedia. Com for article titled

Water hammer noise

Reader follow up:

Thank you for your prompt reply. It is a Whirlpool 50 gallon gas water heater.

I’m almost certain the single sound is from the water heater itself. Sounds like from the inside. Only when hot water is turned on.

Reply: more on banging noise at water heater

that's not typical in my experience but it does happen and could be an expanding metal component in the heater as it warms up.

The longer-term concern is whether or not that particular piece that is flexing is going to result in a leak in the heater. I really don't know how to determine that.

I think the best approach would be to make a note of the model and serial number of your heater and then give the manufacturer a call. If you need help finding that number let me know.

 

Question: banging noise at hot water pipes

everyday we hear this banging noise like if the pipes are coming apart, it goes off all day, should we turn of the tankless water heater or is there a suggestion that may help? On 2018-01-23 by Steve

Reply:

Steve

Search InspectApedia.com for WATER HAMMER NOISE DIAGNOSE & CURE to see the common causes and cures for the noise you describe. Let me know how that works out. Daniel

Question:

Just bought a house and now that the heat is on the past 2 nights we hear a bang like something has fallen could that be the gas hot water heater? It is very scary sounding.

Or could it be the heating system?

On 2017-11-12 by Billie j.

Reply:

Billie,

I agree that you need to do some more careful snooping around when the heat is turning on and when the hot water is being heated. For example if your heat is produced by for Stormare you could be hearing a sound of expanding duct work. Or you could need to descale your water heater.

Knocking Water Heater Noise

water heater keeping a knocking noise when heating. What would cause that? - On 2017-05-23 Charles Brinker

by (mod) re: water heater knocking, banging, rumbling, clunking, gurgling, popping or thumping noises and scale deposits

Typically, Charles, the problem you describe is caused by water heater scale mineral deposits.

You can see live links to recommended cures in WATER HEATER NOISE near its end in the section titled "Cures for Hard Water that Clogs Hot Water Tanks, Tankless Coils, and Plumbing Pipes"

or you can Use the search box just above to find our article series

on WATER HEATER SCALE DE-LIMING PROCEDURE

Water Heater Chugging Noise FAQs

Chugging noise at Kenmore water heater

I have a Kenmore water heater from 99 and the junction box connected to it is making a chugging noise. There is a bar on the side of it you can slide up or down. It was up when it was making the noise we put it down and the noise stopped.

Does that mean there is a problem with my water heater or my electrical box? Don't know what to do... since noise started I have to constantly press reset button on water heater. On 2013-03-24 by Belinda -

Reply by (mod) - chugging noise from water heater

Belinda
I don't understand from your question

- what kind of water heater is installed: electric, oil, gas, other
- what junction box you refer to: a control, electrical switch, safety device

But I infer from your mention of a reset switch that you're talking about an electric water heater that keeps going off on reset. I would NOT keep forcing the heater to run as doing so may be unsafe. It's time to call a plumber or an electrician who is familiar with water heaters - for accurate diagnosis and repair.

by Belinda

Thanks yes its an electric heater and I have press the reset button 3 times since we bought the house. There a thick yellow cable that comes out of the top of the water heater that goes into a box.

Then there's a another cable connecting that box to another box. The second box is what is making the chugging noise.

But if you say having to press the reset button is bad then I guess I can start with replacing the water heater thanks

by (mod) - Before replacing the whole water heater let's find out what's wrong.

Hang on Belinda,

Before replacing the whole water heater let's find out what's wrong.

You are describing a noise that comes from a separate control not from the heater itself.

Perhaps the control is a timer - if it has an openable door open that and take a look; if wires are exposed DO NOT TOUCH anything - risk is electric shock.

I suspect either a bad water heater thermostat or a bad electric water heater element. Both of those are parts that can be replaced without replacing the entire water heater.

by Belinda

Thanks the box does have a door and when we bought this house there was a brand new spare element in the utility closet so maybe a job never finished. I will see how it goes...

Water Heater Clicking Noise FAQs

Clicking noise at gas water heater

My gas water heater works fine but I can hear the gas clicking on more now heating the tank. Should I be concerned? (Oct 15, 2015) Deena

Reply:

Deena

Watch out: for safety, let's be sure that there's not a problem with the gas flame igniter at your water heater.

Older gas water heaters user a standing pilot to ignite the burner flame when, as water heater temperature drops, the main gas valve opens.

But newer water heaters use an intermittent ignition. An electric igniter makes a tiny spark to ignite the gas flame when the heater's gas burner needs to turn on.

If you watch your water heater when hot water is being used, and if it's not using a standing pilot, you may hear a little "CLICK!" and even a little "WHOOF" or "WHOOSH" sound as the gas valve opens and the igniter lights the burner.

But if the burner is having trouble igniting you may hear repeated clicks or buzzes without the burner getting going. If you see that, for safety turn off the water heater and call for repair.

Run hot water long enough that the gas burner needs to turn on.

Other gas fired water heater noises are discussed

at GAS FLAME & NOISE DEFECTS.

But I suspect you're hearing a noise caused by lime deposits.

In the ARTICLE INDEX found at the More Reading links at page bottom see

WATER HEATER SCALE DE-LIMING PROCEDURE

 

Gurgling Noise at Water Heater FAQs

Photo: quite a bit of work is needed to actually remove heavy scale from inside of a water heater. Simply draining it through the bottom stopcock won't work.

Loud gurgling sounds at water heater tank

Is there a way to fix the tank from making loud gurgling and loping noises? - Apr 23, 2015) ann said:

Water heater boiling water noise

My gas water heater makes strange sounds when the burner is heating the water. The sound is similar to that of rapid boiling water?

What could cause this sound and how can I eliminate the noise. The water heater sounds like it is about to blow up? 2015/12/07 John J Schmidt said:

Reply:

Yes Ann

see

WATER HEATER SCALE DE-LIMING PROCEDURE for how to eliminate or at least reduce this noise.

The repair will make your water heater more efficient, lowering your hot water cost, and it may also extend the life of the heater and can even help it to heat more water faster than when it's scale coated inside.

Loud gurgling at water heater

Hi, I have a 8 year old water tank in a house that we just purchased.

The hot water supply is fine however if somebody takes a shower and then goes over to a sink to brush their teeth etc. there is a very loud gurgling noise that comes from the hot water tank. Any idea what that is?

Everybody keeps saying its sediment. I have flushed the tank and hot much came out. I do not know the history of maintenance of the tank.

Any ideas what would cause this issue? (Jan 3, 2016) Eric Turner

Reply:

I agree, more or less, withe "everybody" that sediment or more likely scale in the water heater is a common source of heater noises.

And I can tell you from direct experience that if there is a lot of scale in a water heater, it's a challenge to clean it out.

For example, just opening the heater's bottom drain valve will never flush out a lot of sediment.

We usually have to remove the drain valve and often open other spots such as at a temperature sensor, then flush the heater repeatedly.

See WATER HEATER FLUSH PROCEDURE for our detailed procedure for draining and flushing out water heaters to remove scale, dirt, or debris - a first step in cleaning a water heater to increase hot water quantity, temperature, and water heater life, and to stop water heater noises.

Hissing Sounds at Water Heaters, FAQs

Hissing noise at my GE water heater

We have a 50 gallon GE tank that we just had installed one year ago. My husband noticed a "hissing sound" and turned off the heater via the breakers.

I turned it on approximately 6 hours later and I can still hear the hissing sound.

Can you please advise what you think it may be. We are only 10 days out of the warranty coverage and hate to call a plumber if not necessary. Thank you! On 2013-03-25 by Lisa -

by (mod) -

Lisa,

A hissing sound in an electric water heater could be normal - the element heating up, perhaps more so if it is mineral-coated. Is your home served by hard water?

by Lisa

Yes sir, we do have hard water. I've just had people tell me to be careful of it "blowing up", which of course worries me. We haven't cleaned it yet since it's just now one year old, would you advise us to do that?

by (mod) -

Lisa,

Watch out: Just to be sure we're SAFE, make SURE that the noise is coming from the heater interior - that is we aren't facing a burning-up electrical switch or fuse box or control. If you smell smoke or hot plastic or the like be sure to shut the system off immediately - at the electrical panel.

But most likely and what I suspect , the hissing is crud on the heating elements.

Take a look at

WATER HEATER SCALE DE-LIMING PROCEDURE

But more likely you'll need to remove and descale or replace the heating elements. If you can install a water softener you can cope with this problem for all of your plumbing system.

I'd think about that because just making it for one year from new to having a water heater scale problem is pretty fast and inconvenient.

Humming Water Heater Questions & Answers

Question: My AOS water heater is Humming

Why my a.o smith makes a humming noise. - 2019-05-10 by Armando -

Reply by (mod) -

What's the heat source: oil, gas, electric? Look for a defective control, low voltage transformer, motor that's not running.

Question: Low humming sound coming from the hot water system

There appears to be a low humming sound coming from the hot water system - 2017-05-24 by Ronald W T Bull

Reply: Cure a humming noise at a water heater

Thanks for the great question, Ronald.

At WATER HEATER NOISE we describe several causes of humming sounds at water heaters, calorifiers, geysers or cylinders - the term depends on where you live. The most-common cause of humming water heaters on electric models is a vibration at the heating element caused by water turbulence. Here's what to do:

Humming sounds from an electric water heater can be caused by turbulence in water inside the heater as water flows around its one or two electric heating elements.

Some heater experts suggest trying to slightly tighten the electric heater element in its mount to stop or reduce its vibration. By turning the (loop-shaped) electric heater element in position inside the heater you are changing the direction of water flow across that element as water enters and leaves the heater.

That may stop the noise. If it is impossible to rotate the heating element clockwise (rightie-tightie) you can still make an adjustment by loosening the element - turning it counterclockwise. But watch out for leaks. If leaks start you'll need to drain the heater, remove the element, apply new teflon paste or tape to the treads, and position it anew in its mount.

At that point, just tighten the element enough that it's secure and not leaking (on re-fill of the heater). Then if the noise is absent, stop there. If the noise is present you'll be able to rotate the element 1/8 of a turn at a time until the noise stops.

Watch out: never turn an electric water heater back ON before making sure that all of the air has been removed from the tank or the element will burn up immediately.

If that has no effect, I'd also try slightly closing the control valve on the heater's cold water inlet side to see if slowing the water flow rate/volume has an effect.

Check those two points and let me know if that works for you, as what you find will help other readers.

Water heater makes a loud high pitched humming noise

Our new electric water heater (3 months old) is making a very loud high pitched humming noise, any idea why? On 2016-08-21 by Azcabin

by (mod)

I don't know what the humming is, Az.

On a few water heater models, particularly those using a rather long heating element, water flowing across the element may cause it to vibrate and may generate a humming sound.

You can probably diagnose this cause of humming electric water heater noise by turning off water into the heater or by making sure that nobody in the building is running hot water. If no water is running through the heater and the noise stops, you've found the probable cause.

If the humming IS traced to the heating element, ask your installer to inspect the element installation; simply tightening it may stop the humming noise.

Watch out: left-unattended, a humming vibrating electric water heater element might begin to leak at its mount.

Is there a circulator on your water heating system? If so check the pump for noise.

Watch out: a failing or mis-wired electrical circuit could cause buzzing or humming - that would be unsafe.

Are you sure it's really humming and not rumbling or hissing -sounds associated with scale deposits or simply with water heating up>?

Try turning power to the heater off, wait 5 minutes, then turn it on. Let me know what you observe.

Finally: a new heater and its installation should be under warranty so it makes sense to call the installer for help.

Jackhammer noise at water heater if hot water tap isn't fully "open"

We have a rental property and our gas hot water system in the downstairs unit makes a massive noise (like a jackhammer) which can be heard in the upstairs unit. It only happens when the hot water tap isn't fully turned on. Once it is, the noise stops. No other taps cause this problem? On 2013-03-13 by Annie -

Reply by (mod)

Annie,
The noise you describe sounds like pipe vibration, similar to water hammer. It occurs when water flowing through a pipe or sometimes even a particular fixture sets up a vibration that (I think) is a harmonic interaction with a particular length and run of pipe. Water pressure is also a factor.

I've had successful cures by finding and securing poorly-supported water supply pipe runs, and on occasion I replaced a faucet.

A complete explanation and remedy advice are

at WATER HAMMER NOISE DIAGNOSE & CURE