Noisy Water Heater Repair &
Troubleshooting Guide
(updated 2017)

Noisy water heater troubleshooting guide helps you explore the common sound problems in residential water heating and how to troubleshoot annoying and loud noises like rumbling, ticking, pounding, hissing, clicking, knocking...

Water heater noise is usually associated with the two main conditions; water hammer and mineral build-up (sediments), but there are also other reasons for a noisy heater and strange sounds in plumbing.

It is common to experience the annoying noise your water heater makes after a short period of service. Even if your heater is installed in the area away from the living or sleeping room, you might hear a noise in the plumbing that travels with a vibration wave from the heater. Some users complained that the noise appears only at night, some saying in the morning, right after the unit was turned ON, after the shower, etc.

The noise, for example, can come either from the gas heater due to the droplets on the crusty formations and sediments; or is associated with the hissing sound on electric units and formation of limescale on the immersed heating elements.

The most common symptoms of water heater noise

Pounding Noise

Why my water heater is making a pounding noise?

Mineral buildup and water hammer are the main causes of the pounding noise your heater makes.

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

Pounding noise, including knocking sound are associated with the water hammer occurrence. Details on how to solve the problem with the pounding/knocking noise the system produces, you can find in the article about fixing water hammer.  A solution is to install the water hammer arrestor.

Pounding noise can occur due to lime formations and sediments at the bottom of the tank. To eliminate the noise some professionals will recommend installing a water softener or flushing the system occasionally. How to troubleshoot sediment problem and noisy water heater due to the limescale; check out the article about sediments and lime build-up.

Rumbling sound

Aluminum hydroxide gel in tank or plumbing is one of the main causes of the rumbling noise in the heaters, while the mineral buildup can also be a factor. The aluminum hydroxide gel is the result of the chemical reaction between the anode rod and water condition.

These blue, green or gray gel beads tend to accumulate in the heater drain or in faucet aerators.

A solution for the water heater noise problem is as follows:

If the heater is new and has no lime build-up, simply turn the heater off, remove the anode rod and flush the system thoroughly. Bring the anode back and run the heater.

If there is a lime buildup, use one of the recommended delimers (phosphoric acid for example or one recommended by the manufacturer) and follow the procedure for flushing the deposits.

Ticking sound

Ticking noise is usually caused by fluctuation in pressure in the piping system. If your heater is an energy efficient unit, the odds are that it has heat traps installed. Due to temperature change; expansion and contraction of the elements, heat trap ball is rattling in the nipple.

If there is no other way to eliminate this ticking noise, simply remove the heat traps from the heater. There will be only a minor reduction in the energy efficiency, without affecting the safety of heater's operation.

Another reason for ticking sound might be in the plumbing pipes, due to expanding and contracting against a loose strap or wood framing while making a hot water draw. One of the solutions for this sound is to track down where the ticking noise is the loudest, secure the pipe or install plastic spacers.

The simplest solution: Turn the temperature on your heater just a few degrees down.

Popping and crackling sound

Lime (CaCO3) in the heater is the result of the water hardness, present almost in every home plumbing, more or less. More lime is created as the water is heated longer and due to higher usage in the excessive hardness environment.

Popping and crackling noise are one of the symptoms where water is trapped under the lime deposits. A Solution for the noisy water heater due to lime buildup is simple, flushing the heater with the proper acidic compound (delimer recommended by the manufacturer).

If the flow is also stopped abruptly it can also cause the popping or crackling noise.

Another reason for crackling might be condensation dripping on the burner or any other hot part's surface.

Sizzling noise

The main reason for sizzling noise in your gas water heater is due to condensation or leaking problem; when the water drops are dripping down the flame, in the burner or hot surface.

Condensation is created when the hot flue gases are in contact with cooler surfaces. Condensation will form inside the vent and the drops of water will hit hot surface every few seconds making the sizzling sound. It can be seen by looking in the combustion chamber where the flame will first grow very bright and then very dim.

Keep in mind that on some older units, even half a gallon of water vapor can be produced every hour of operation.

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

A sizzling gas heater can be very normal as the natural gas has a very high moisture content and therefore in products of combustion.

On the heating elements of the electric water heaters, due to limescale, water trapped next to the element will also make the sizzling noise, boiling the water to steam.

Hissing sound

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

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

Also, the water heaters can make the hissing noise when the air is escaping through the TPR valve. By turning down the temperature the sound can be eliminated. If the noise and leaking come together, you might want to consider replacing the TPR valve.

Conclusion

Water heater noise can be reduced by disconnecting the heater and with a regular flushing. This is the most common solution. If the water is too hard, you might want to consider installing a softener but consider a negative influence of softer water on the anode rod.

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

The noisy water heater is not dangerous but is a good indication that either you have missed a regular maintenance and the unit needs one, or one of the mentioned elements have to be replaced. If the unit service is hard or you don't know how, check out this company, they will provide you with three free estimates, so you can choose either to make a service call or just do it.

Related articles

Failure signs
Pilot light goes out, what to do
Fixing the temperature fluctuation
What is  condensation and how to stop it
Bulging

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