Water heaters are generally incredibly well-insulated — so why can you still hear that noise? Unfortunately, the inches of polyurethane foam surrounding the main tank can’t guarantee silence. Simply put, water heaters can produce a wide range of sounds. The trick is in understanding which ones you shouldn’t be hearing.
Usually, the sounds that get on your nerves are the result of sediment buildup on the heating elements inside the tank. So, in addition to sharing some ways to address the underlying issues behind the noise, we’ll also discuss preventative measures.
But first, let’s take a peek inside a water heater and see what might be causing the noises you’re hearing.
Water Heater Noise Overview: What You Should Expect
Now, water heaters naturally produce a variety of sounds. However, while the sound of running water and the buzz of the heating elements are probably benign, crackling could indicate sediment buildup. And that’s not the only issue that might make your gas or electric heater noisier than usual.
Obviously, the main function of a water heater is to warm up however many gallons of water it can hold at one time. Still, these devices are supposed to keep all that heat contained inside the tank. That’s why most of them have at least an inch and a half of insulating foam between the inner tank and the outer shell of the heater.
In fact, the National Appliance Energy Conservation Act of 2015 (NAECA) mandated that new models must accommodate thicker insulation. They had to be at least two inches wider and two inches taller in comparison to older models of the same capacity. These precautions were taken to maintain energy efficiency by making sure that the heater won’t lose that warmth. However, it would be reasonable to assume that models sold after 2015 are also quieter than their precursors.
But before we consider the different kinds of noises a water heater might make, let’s talk about the anatomy of the two main types of heaters.
Gas Burner vs. Electric Heating Elements
Even though gas water heaters are more expensive from the get-go, they’re the cheaper option in the long run. However, as most gas appliances, they’re louder than electric heaters. After all, their burner setup includes an open flame — which may produce the typical whooshing sounds.
Since we’re already talking about gas units, let’s start by looking at their heat source. Located in a separate chamber at the bottom of the device, the gas burner will be on until a certain temperature is reached. Users can control those temperature settings through a gas control valve outside of the tank. The protruding control panel is actually one of the main external differences between gas and electric units.
Inside the tank, a gas heater has a long chimney that helps the carbon monoxide fumes escape to the top of the tank and out the flue vent. Inside the internal chimney, you’ll find a zigzag-shaped baffle, which slows the ascend of the hot air. That transfers its heat to the metal chimney and the surrounding water, achieving an even distribution of warmth.
Now, while a gas heater has the flue vent sticking out from the top, an electric one has a much simpler appearance. The top contains the cold water inlet, hot water outlet, and some wiring. Furthermore, electric units don’t have that big central pipe inside the tank because they don’t produce any fumes.
Still, they have to achieve an even heat distribution somehow. Usually, that’s done by utilizing two heating elements or U-shaped bars that penetrate the tank horizontally. They have separate thermostats that are accessible by removing the panels on the outside of the device. However, they also work together, switching off when the water achieves a certain temperature.
Dip Tube Water Inlet
Both gas and electric water heaters have the same cold water delivery systems. Namely, the cold water pipe is connected directly to a long dip tube, which lowers the water to the bottom of the tank. That means that the cold water is delivered close to the heating elements.
The end of the dip tube has several slanted openings the cold water shoots out from. That makes the water swirl in the tank, displacing and reabsorbing any loose minerals. However, it’s also likely to cause some banging sounds, if the buildup has gotten out of control.
Still, thanks to the dip tube, you shouldn’t hear the sound of water rushing into the tank. Of course, if the tube is dislodged near the top, you might still hear that noise. Fortunately, most elements of a water heater are made to be easily replaceable. The only thing you can’t replace is the tank.
Sediment Buildup and the Role of the Anode Rod
Sediment is something that could easily take your water heater out of commission. However, if you perform regular maintenance, you could prolong the lifespan of your tank by many years. All you’d have to do is regularly drain it of water and mineral buildup.
Even though the inside of the tank is made of steel, which is corrosive, it’s also coated with enamel. That layer should postpone the onset of rust, but it’s not the only thing protecting the inside of your water heater from the dreaded sediment buildup.
However, in addition to the dip tube, there is another pipe that comes down into the tank. The anode rod has a steel core and is usually coated with magnesium, aluminum, or zinc. Its primary role is to “sacrifice” itself the moment the steel interior of the tank starts breaking down.
It will either send pieces of itself to patch up the fissures in the inner walls of the tank or take on the oxidation process. Either way, the anode rod should show signs of wear long before the inside of your tank does.
Still, sediment buildup is a problem you’ll have to deal with in one way or another. It’s the primary cause of most types of noise you might encounter. But as you’ll see, there are several ways to go about fixing that. However, you must act swiftly and rely on preventative measures as much as you can.
Problem #1: Water Heater Making Noise Like Water Running
If you heard the sound of running water coming from your water heater, find the exact place it’s coming from. On the one hand, the noise might be completely normal if you only hear it when someone opens a tap somewhere in the house. However, it might also be the result of a leak.
In that case, you’ll want to take care of the issue as soon as possible. After all, leaks will not only make your bills more expensive but also damage the floors and walls around the heater.
What Is Causing the Water Running Noise?
If your water heater is making noise that sounds like running water, you have a leak on your hands. The first thing you’ll want to do is establish where the excess water is coming from — or going. After all, the heater may not even be the source of the leak.
If you turn off all the faucets in your home and give it a moment, you should be able to touch the hot water pipe on top of the heater without scalding yourself. However, if it’s still hot, it would mean that the heater is sending water somewhere in the house even though all the taps are off. At that point, you might need to call in a plumber to locate the leak, as it might be hidden inside your walls.
On the other hand, if that pipe is cool to the touch, check the tube or pipe that’s attached to the temperature and pressure relief valve. You’ll find that part either on top of the heater or somewhere on the side. If the tube attached to it is hot, you’ll just need to fiddle with the valve to ensure that it’s fully closed. Worst case scenario, you’ll have to replace the part — which we’ll talk about later on as well.
How to Fix It
Before touching any part of your water heater, you should cut off the water inlet line and disconnect the electricity or gas supply. If you have time, wait for the tank to cool completely to avoid being scalded. Once it’s cool, you’ll be able to address the sound of running water by:
- Tightening the connection between the cold and hot water pipes and the steel connections on the tank. If you have copper plumbing, you’ll want to have a di-electric union between the two to prevent electrolytic corrosion. After all, if one of those pipes oxidizes, it’ll be more likely to leak.
- Slowly opening and closing the T&P valve — but only if it’s connected to a tube that leads almost all the way to the floor. Making sure the valve is closing properly should stem the flow of water. If it doesn’t, you can switch the valve out with a new one — just make sure you’ve got the right size!
- Installing a drain pan under the water heater and connecting it to a floor drain. That should protect your floor from potential water damages.
- Calling the plumber if you discover a leak, whether by touching the pipes when the taps aren’t running or by comparing water meter readings.
Problem #2: Hot Water Heater Making a Knocking Noise
There are several potential causes that might explain a persistent knocking noise coming from your water heater. It’s either a phenomenon known as a water hammer or plain old mineral buildup. Both of these things can be dangerous for your device or even your whole plumbing network. So let’s see why they might occur.
What Is Causing the Knocking Sound?
An occasional knocking noise is an indicator of hydraulic shock, otherwise known as a water hammer. If you hear the sound only when someone turns the tap off after running it for a long time, that sudden pressure surge might explain it. However, sediment buildup can cause a similar sound.
But to begin with, let’s take a look at our first explanation more closely. For example, imagine taking a long shower. The water heater would need to work overtime to heat the cold water, rushing to fill the tank and deliver the hot water to you. So when you suddenly turn the showerhead off, all that water will hit a wall, causing it to go back to where it came from.
Therefore, the knocking could be explained either by the initial impact of the water hitting the closed shower valve or by the force with which it hit the water heater on its way back. Some experts even claim that force is strong enough to cause a burst pipe or warp the heater tank.
On the other hand, if it’s just calcium and magnesium buildup, the knocking could be caused by the cracking of a solid mass of minerals. The swirling of new, cold water can cause the sediment to break apart and knock against each other and the inside of the tank. In both cases, though, the issue should be preventable.
How to Fix It
If you haven’t flushed the tank in a while, make sure the water is free of sediment. Again, you’ll have to turn off the electricity or gas supply to the heater as well as the water before you do anything. After waiting for the water inside to cool for a while, you’ll be able to attach a garden hose to the drain valve. Finally, open the valve and let the water flow into a nearby drain or deposit it into buckets until it runs clear for at least a minute.
On the other hand, if you find that the concept of a water hammer perfectly explains what’s been happening, you might prevent potential plumbing issues by simply installing a water hammer arrestor. That little add-on can absorb the shock of the water rushing back toward the tank and prevent the excess pressure from wreaking havoc on the entire plumbing system. You’ll find a great product demo and installation guide in this video.
Problem #3: Water Heater Is Making a Vibrating Noise
If your heater is making a vibrating or rumbling noise, it’s probably due to calcium and magnesium buildup. However, if you have a gas heater, the burner might be another potential explanation.
What Is Causing the Vibrating Noise?
While sediment buildup is the most common cause of water heater noise, vibrations can also be explained by a malfunctioning gas burner. However, fixing the former will be significantly easier than dealing with the latter. So let’s start by seeing why that is.
You already know that sediment buildup is the result of calcium and magnesium particles that come from the water. That issue can be addressed by regularly flushing the tank. As a preventative measure, you could also use products that will keep the minerals in the water.
On the other hand, if you determine that the gas burner is the cause of the noise, fixing it may be a bit more difficult. As we have established, most parts of a water heater are fully replaceable. However, many water heater manufacturers will only send a replacement burner to a licensed professional. Even though the replacement process itself is relatively simple, they (understandably) don’t want you messing with gas.
How to Fix It
If you believe sediment is behind the vibrating noise, you can get rid of it by flushing the tank. Turn off the electricity or gas, as well as the water supply, attach a garden hose to your drain valve, and let it all out. You don’t even have to drain the whole thing, just wait until the water isn’t orange and let it run clear for about a minute.
On the other hand, if the burner is the problem, you’ll probably have a hard time finding a replacement gas assembly for your exact unit online. You’ll have to speak directly to the manufacturer, which may offer to send the replacement to a specialist. However, as you’ll see in this video, the whole thing isn’t that difficult to remove.
So if you want to try to fix the problem yourself before handing it off to a professional, you could open the burner up and see which parts could be rubbing against each other. In the video, the answer is clearly indicated by the scratches on the interior sides of the burner. If you find anything that obvious, you should be able to fix it yourself. But be advised: doing so will void your warranty.
Problem #4: Electric Hot Water Heater Making a Humming Noise
Humming is a pretty normal sound you might hear coming from your water heater, especially if it’s an electric unit. However, there are still some things you can do to reduce the sound.
What Is Causing the Humming Noise?
A humming sound is something both gas and electric water heaters can produce. If you have an electric heater, the humming may be caused by the vibrations of one of the heating elements. On the other hand, if you’ve noticed the same noise in a gas heater, it’s probably just the burner.
If you’re dealing with a low-level humming sound, you won’t need to repair anything at all. However, as the water swirls around your heating elements, it might shake them loose over time. So if the hum develops into a more serious vibration, you might have to tighten the heating elements. But doing so should be easy enough — you won’t even have to drain the tank!
How to Fix It
Even though draining the tank won’t be necessary, you’ll still have to shut off the electricity before you go in to tighten the elements. Once you do, you’ll:
- Figure out which element is causing the noise — or just tighten both
- Use a screwdriver to remove the panels that are hiding the thermometers for each of the elements
- Flip the layers of insulation up and tape them out of the way
- Tighten the heating element with a special wrench socket (which you’ll also need if you ever need to replace the element)
Hopefully, that will be the end of that noise. But really, the occasional humming sound is all within the normal range of operation for most water heaters. If that’s going to be annoying, you might want to consider moving the appliance to the basement.
Problem #5: Hot Water Heater Making a High-Pitched Noise
There’s nothing more frightening than hearing your water heater producing the most bone-chilling high-pitched noise ever. But is it always as scary as it sounds?
What Is Causing the High-Pitched Screech?
If your water heater is making a high-pitched sound, you should check the valves on top of the device. Alternatively, if you’re dealing with a gas heater, you’ll want to start with the gas supply pipes. A blockage in those lines could have disastrous consequences if you don’t address it on time.
So if you have a natural gas heater, start by turning the flame off. If the noise cuts off immediately, you’ll know that the noise isn’t being caused by the water pressure. Instead, the problem might be in the gas supply pipes.
If there’s a blockage in the lines, the gas might be squealing as it pushes through a narrow opening. But of course, noise won’t be the worst of your problems if the pipes develop a complete blockage.
On the other hand, if the noise isn’t coming from the bottom of the tank, where the gas lines should be, it might be a valve issue. That would be much easier to handle.
How to Fix It
If a blockage in the gas pipes is causing the high-pitched noise you hear near the water heater, you should:
- Shut the gas off immediately. Better safe than sorry.
- Call a water heater repair service. They might be able to see if the deformation is in the gas jets, not the mainline. However, if they find nothing wrong with the jets, you might have to contact your gas supplier.
Now, there’s a chance that the high-pitched sound is caused by the valves on top of the water heater. You’ll have to open and close them to determine if that’s the case. If the sizzling noise persists, the water may be squeezing past a narrow opening because the valves aren’t shutting properly. You might have to replace them entirely.
However, if it turns out that the gas line is the culprit, you should prepare to shell out some cash for repairs. After all, if you don’t fix whatever is wrong as soon as possible, the whole thing might end up literally blowing up in your face.
Problem #6: Water Heater Making a Hissing Noise
Hissing sounds are common in water heaters that haven’t been serviced in a while. The noise is usually a dead giveaway that the inside of the tank is filled to the brim with sediment.
What Is Causing the Hissing Sound?
A hissing noise can indicate that there is a layer of mineral buildup on the bottom of the tank over the gas burner. Alternatively, the sound may also indicate that the temperature inside the tank is too high (which is why you should keep it at 120 degrees Fahrenheit).
Older water heaters used to form a thin layer of condensation on the outside of the tank. When the cool condensation came into contact with the section of the tank that held hot water, it would produce a hissing sound. Nowadays, that isn’t much of a problem due to the increased energy efficiency measures we’ve mentioned before.
At this point, you should already know how to address a sediment buildup. If it’s past the knocking stage and is only hissing, it would indicate that the sediment has trapped water bubbles inside it, which are warming up and evaporating. At that point, the mineral buildup may even be too large to drain.
How to Fix It
Normally, all you would need to drain your tank would be a garden hose with a drain valve connector and a floor drain (although buckets would do). You’d just plug the hose in and open the valve, letting the water out. However, if it refuses to budge, there are some ways to encourage the flow. You could:
- Displace the pressure in the tank by opening nearby faucets. Just make sure you’re running hot water.
- If no water comes out of the hose even after you’ve opened the valve, stomp on the hose. That should send air into the tank, displacing the blockage.
- Lay down some towels and a tray under the drain valve and open it without connecting it to a hose. If it’s blocked, you’ll only see a few spurts of water. Insert a stiff wire into the opening and rotate it to clear the sediment around the valve. Repeat as necessary, shutting off the valve to switch out the water tray or buckets, until the tank is empty.
- Replace the whole drain valve with a brass one which won’t be as corrosive as lead or fragile as plastic ones.
Naturally, you wouldn’t attempt any of that before turning the circuit breaker off or shutting off the gas supply to the unit. Additionally, you might want to wait for the water in the tank to cool before attempting to drain it. It can take up to a full day, so keep that in mind. Alternatively, you could wait for a few hours and leave the cold water inlet on to dilute the hot water as you drain it.
Problem #7: Electric Water Heater Making Popping Noises
Cracking, popping, and rumbling sounds are typical in electric water heaters. They can usually be eliminated by replacing the heating elements.
What Is Causing the Popping Noise?
If your electric water heater is making popping noises, it’s probably due to sediment on the heating elements. You see, if water got stuck under the mineral layer while the element is inactive, turning it on will cause it to boil. The resulting bubbling can make the sediment break off, causing the popping sound.
When the heating element is on, the sediment can’t stick to it. But since water heaters automatically regulate the temperature of the water, you’ll have no say in when the elements are working. Therefore, the only thing you can do is treat the problem when it comes up.
How to Fix It
There is a simple way to determine whether the heating elements are the culprits in this case. First, you’ll need to drain the tank, after shutting off the water and electricity. You can then inspect the elements by:
- Unscrewing the temperature control panels on the sides of the tank. There should be two of them, one lower and one higher up on the appliance.
- Folding up the layers of insulation until you can see the thermometer. The heating element setup should be underneath it.
- Carefully disconnecting the wiring and unscrewing the elements, then pulling them out. They should be shiny, not covered in white calcification.
- Putting in new elements. Simply slide them into the same hole you took them out of, screw them in, and connect the wiring.
If you discover sediment buildup during your inspection, you can put everything back in and put up with the noise until your replacement elements come. Alternatively, you could clean the sediment buildup on the heating elements by soaking them in vinegar and gently brushing the buildup off.
If that doesn’t work or you simply don’t want to wait for the new element to ship to your door, you could get a tune-up kit before there’s a need for one. At this point, I should also mention that there’s a way to replace the element without draining the whole tank. As you can see in this video, you would only need a bucket and funnel.
Problem #8: Water Heater Making a Whistling Noise
There are several things that could make your water heater start whistling. Fortunately, most of them aren’t dangerous or difficult to fix!
What Is Causing the Whistling Noise?
The most common causes of whistling water heaters are loose valves. So the first thing you’ll need to do is check the temperature and pressure relief valve, the drain valve, and the water inlet and outlet. If the culprit is less than obvious, the problem may be with the tank itself.
All of the valves on the water heater are designed to let water in or out of the tank. If any of them aren’t closing, it could result in a whistling noise and leaks. However, since that noise is usually a sign of a pressure release, you ought to start by checking the temperature and pressure relief valve.
Sometimes, though, the noise might come from fissures in the tank itself. If corrosion has weakened the interior walls, the pressure might have caused cracks through which water and air are trying to escape. However, because of the insulation between the inner and outer walls of the appliance, that explanation is less likely than having faulty valves.
How to Fix It
Other than the water inlet valve, most of the other valves on your water heater will let water escape the tank. So you’ll need to keep that in mind when you go in to do your repairs. Shut off the water inlet if you must and make sure the hot pipes are empty before messing with the outlet valve. More importantly, if you have to fix your drain or temperature and pressure relief valves, use a hose to lead the water to a nearby floor drain or bucket.
First things first, you should try tightening (or opening and closing) all the valves. That might help the one that was making the whistling noise close completely. If it doesn’t, you could replace pretty much any valve on the heater as long as you take the time to turn off the water and gas or electricity first. Moreover, before you replace any of the valves, you’ll have to drain at least ten gallons of water out of the tank.
If you’re replacing the pressure relief valve, which is the most likely cause of the whistling noise, you’ll have to use a pipe wrench to twist it out, as demonstrated in this video. However, if you needed to replace the drain valve, you’d need to empty the whole tank.
Problem #9: Water Heater Makes Noise When the Hot Water Is Turned On
Hearing the sound of running water coming from the water heater when a tap is open in your home is normal. However, certain sounds may indicate a larger problem.
What Is Causing the Noise?
If your water heater makes noise when hot water is turned on, there may be an issue with one of the valves. Basically, you’ll have to locate the valve in question and address the issue. Depending on its function, you’ll either want to close or open it fully.
In fact, restricted water flow can cause all sorts of issues. So it’s always good to check if all the valves are shutting properly. Even though the noise you’re hearing is coming from the water heater, any loose valve can be a problem. Still, in this case, you should probably focus on the hot water outlet.
How to Fix It
Assuming you’ve heard the noise around your water heater, you should try to pinpoint its exact origin. It will grow louder as you near one of the valves. However, as most of the valves on a water heater are on or near the top, you might have trouble distinguishing between them. So here’s how you can troubleshoot the issue:
- If the problem is occurring when you have hot water running somewhere in the house, you should start by checking the hot water check valve on top of your heater. After turning off the water and electricity (or gas), you’ll disconnect the hot water pipe and replace the check valve. If the old one was letting the water slip through, it might just have a worn gasket.
- Just to be safe, you could also inspect the water inlet valve. When you close and open it again, the noise should disappear — if that was the problem, to begin with.
- Finally, do the same thing to the temperature and pressure relief valve. If that’s the source of the noise, it might indicate that your heater isn’t filling and emptying properly. You might want to call in a plumber.
Can a Noisy Water Heater Explode?
Some water heaters start making banging sounds that might be a prelude to a combustion reaction. But how worried should you be? Can a noise coming from the water heater cause the whole thing to explode?
Well, the noise itself can’t. However, if the underlying cause is explosive (e.g., gas), then the answer is less hopeful. Still, if you address the issue on time, you’ll have nothing to worry about.
If you want to forestall a disaster, make sure your water heater’s heating elements are all in working order. After all, the only things that could make it explode are gas or electrical parts. So as long as you stay on top of the maintenance, it should be fine.
At this point, you might say that you’ve heard about water tanks themselves blowing up. And, to be fair, that might happen if the interior pressure overwhelms the steel structure of the appliance. However, it won’t happen if the temperature and pressure relief valve is functioning as it should be. Additionally, you’ll want to keep the thermostat at the recommended temperature if you want to avoid damages.
If your water heater sounds like it’s going to blow, you need to shut off the gas or electricity as well as the water inlet immediately. Alternatively, if you sense an imminent threat, evacuate the house and get help. You can call 911 and wait for the fire department to show up, but warn them if you suspect a gas leak.
In this case, the best way to avoid such a calamity would be to follow a strict maintenance plan.
Prevent Your Water Heater From Making Noise in the Future
If you’re thinking about installing a new heater, you have a chance to do it all right! You’ll be able to prevent most of the issues we’ve been talking about by following some common-sense rules:
- Release the pressure valve every month to make sure the interior of the tank isn’t under too much stress
- Drain the tank every year — but if you haven’t drained it in years, don’t start now: the sediment could be the only thing keeping the walls of the tank together
- Consider installing an anti-scale system or water softener to prevent the sediment buildup in the first place
- Examine the heating elements or burner setup yearly and replace them if necessary
- Replace the anode rod when the steel core is completely exposed
- Place the water heater away from the living quarters
Generally, you should be getting at least 10–15 years of use from electric or gas water heaters. However, if you wanted to install a more compact heater, you could go for a tankless unit. With regular maintenance, those can last between 20 and 25 years. But while they do take up less space and save energy, they also take a longer time to heat water.
Ultimately, if you take good care of your water heater, it’ll provide you with plenty of hot water without protesting. Of course, if you’re human, chances are you’ll forget to regularly perform the little maintenance checklist I’ve provided. But unless you let several years pass between checkups, this guide will help you get your water heater up and running again.
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