Noisy Water Heater: Common Causes and How to Fix Them

Dealing with a noisy water heater can be a headache, but ignoring the problem can lead to even more significant issues down the road.

From sediment buildup to malfunctioning heating elements, there are several potential causes of this problem.

Fortunately, with the right troubleshooting and repair techniques, it is possible to address these issues and get your water heater running smoothly and quietly once again.

In this article, we will explore the most common causes of the noisy water heater such as: rumbling, ticking, pounding, hissing, clicking, knocking… and provide practical tips for troubleshooting and repairing.

How to Fix a Noisy Water Heater: The Most Common Signs

Water heater noise is typically associated with two main conditions: water hammer and sediment buildup. However, there are also other reasons for strange sounds in a water heating and plumbing system.

It’s common to experience irritating noises from your water heater after a short period of service. Even if your heater is installed in an area away from the living room or bedroom, you might still hear it in the plumbing that travels with a vibration wave from the heater. Some users have reported that the noise only appears at night or in the morning, right after the unit was turned on or after a shower.

The noise can be caused by the gas heater due to droplets on crusty formations and sediment buildup, or electric units characterized by a hissing sound and the formation of limescale on the immersed heating elements.

Here are the most common water heater sounds you might hear:

What Causes Pounding Noise in a Water Heater and How to Repair It

Why my water heater is making a pounding noise?

Mineral buildup and water hammer are the leading causes of the pounding noise your heater is making.

When water is flowing through the plumbing system and is stopped suddenly, the high intensity shock wave travels through the pipeline, creating vibration in the piping system followed by pounding, banging, and thumping noises.

The pounding noise, including the knocking sound, is associated with the occurrence of water hammer. For a solution, you can find details on how to solve the problem with the pounding/knocking noise the system produces in our article about fixing water hammer.  One solution is to install a water hammer arrestor.

The problem can also occur due to lime formations and sediments at the bottom of the tank. To eliminate the problem, some professionals recommend installing a water softener or flushing the system occasionally. For more information on troubleshooting the sediment problem and noisy water heater due to limescale, check out our article about sediments and lime build-up.

What Causes Rumbling Noise in a Water Heater and How to Fix It

Aluminum hydroxide gel in the tank or plumbing is a major cause of the rumbling noise in water heaters, along with mineral buildup. This gel forms as a result of a chemical reaction between the anode rod and water condition, and appears as blue, green, or gray beads that tend to accumulate in the heater drain or faucet aerators.

To address the problem, here are the steps to follow:

• If the water heater is new and has no lime build-up, turn off the heater, remove the anode rod, remove the anode rod, and flush the system thoroughly. Then reinstall the anode rod and turn the heater back on.
• If there is lime buildup, use a recommended delimer (such as phosphoric acid or one recommended by the manufacturer) and follow the procedure for flushing the deposits.

Troubleshooting Water Heater Ticking Sound

The ticking noise is usually caused by fluctuations in pressure within the piping system. If your water heater is an energy-efficient unit, it likely has heat traps installed. Due to changes in temperature and the resulting expansion and contraction of the elements, the heat trap ball can rattle inside the nipple, causing the ticking noise.

If there is no other way to eliminate this sound, simply removing the heat traps from the heater can be a solution. This will result in only a minor reduction in energy efficiency and will not affect the safety of the heater’s operation.

Another reason for the ticking sound might be in the plumbing pipes themselves, due to expansion and contraction against a loose strap or wood framing while hot water is being drawn. One solution to this issue is to track down where the noise is the loudest and secure the pipe or install plastic spacers.

A simple solution to reduce it is to turn down the temperature on your water heater by just a few degrees.

What Causes Popping and Crackling Sound and Solution

Lime (CaCO3) is present in almost every home’s plumbing due to water hardness, and more limescale can accumulate in the water heater with prolonged heating and higher usage in excessively hard water. Popping and crackling noises are signs of water trapped under lime deposits.

To address this problem caused by lime buildup, you can flush the heater with the proper acidic compound, such as a delimer recommended by the manufacturer.

A sudden stop in water flow can also cause a popping or crackling noise. Another possible reason for crackling is condensation dripping on the burner or any other hot surface.

Sizzling Noise: What You Can Do to Repair It

The main reason for a sizzling sound in your gas water heater is a condensation or leaking problem, which occurs when water droplets drip down onto the flame, burner, or hot surface.

Condensation is formed when hot flue gases come into contact with cooler surfaces, causing it to form inside the vent. The drops of water then hit the hot surface every few seconds, creating the sizzling sound. This can be observed by looking into the combustion chamber, where the flame will first become very bright and then very dim.

It’s important to note that some older units can produce up to half a gallon of water vapor every hour of operation.

Condensation should stop when the entire heater is heated to above 115 F. If the problem is leaking, the solution is to locate and repair or replace the leaking element or tighten any loose fittings.

A sizzling gas heater can be normal, as natural gas has a high moisture content, which is released during the combustion process.

On electric water heaters, the heating elements can also cause sizzling noises due to limescale buildup. Water trapped next to the element boils, producing steam and the sizzling sound.

Troubleshooting Hissing Sound

The hissing sound is mainly found in electric water heaters with corroded heating elements when water comes in contact with the electrically hot part of the element.

The same sound is heard when the heating element is ON, and water trapped under the scale formed on the elements turns into steam. This is also an indication that your water heater needs flushing, as the efficiency drops.

Water heaters can also make a hissing noise when air is escaping through the TPR valve. By decreasing the temperature, the sound can be eliminated. If it occurs together with leaking, you might want to consider replacing the TPR valve.

Understanding and Addressing Banging Noises in Your Water Heater

Banging noises from water heaters can sometimes originate from the flue—the component that expels combustion gases to the outside. Central to the flue’s operation is the baffle, a metal device designed to slow down the air movement through the flue, enhancing the heater’s efficiency by maximizing heat transfer to the water. Over time, this baffle can begin to wiggle within its mounting bracket due to the flow of air and vibrations during operation, leading to metal-on-metal clanging sounds as it strikes the sides of the flue tube.

To mitigate this issue, one effective solution is to adjust the fit of the baffle within the flue. This can typically be achieved by tightening the baffle’s mounting by bending the metal tabs on the hanger bracket. Alternatively, removing the baffle, slightly bending it for a better fit, and then reinstalling it can also ensure a snugger and quieter operation. These adjustments help secure the baffle, reducing noise and maintaining the heater’s performance without compromising its design or efficiency.

Water Heater Making Humming Noise

In electric water heaters, a humming noise typically comes from a loose heating element. These elements, installed inside the tank, can vibrate when water flows past them if not securely tightened. Sediment buildup in the tank can further amplify these vibrations, making the hum louder.

Usually, tightening the heating element and flushing the tank will resolve the issue and eliminate the noise.

In gas water heaters, humming sounds are less common but can still occur. They are often caused by loose burner components or sediment buildup at the bottom of the tank. An unstable burner flame can create vibrations if parts are not secure or if the tank base is uneven.

To fix this, secure the burner components and flush the tank to remove sediment.

Conclusion

Reducing water heater noise can be achieved through regular flushing and disconnecting the heater, which is the most common solution. If your water is too hard, you may want to consider installing a water softener, but keep in mind the negative effects of softer water on the anode rod.

Use the following article to learn about lime build-up and deliming process.

A noisy water heater is not dangerous, but it is a good indication that you may have missed regular maintenance and the unit needs service or one of the mentioned elements is failing and requires replacement.

If servicing the unit is difficult or you don’t know how to do it, check out this company that provides three free estimates, allowing you to choose between making a service call or doing it yourself.