Water heater noises like, popping, cracking, humming, sizzling, hammering, banging, etc. can be minor or serious, depending on which noise it is. You will notice these annoying noises more if the water heater is located in the house, especially in a hall closet, than if it is located in a garage.
Electric water heaters generally have a looped tube heating element that is installed in a vertical position in the tank. When the water flows through or past these, the water flow may create a small vibration of the heating element. Thus a humming sound which is more annoying than serious.
If you turn the water off to the heater and there is no running water and the noise stops, then you can guess that you have identified the problem. At times, slightly tightening the heating element will solve the issue.
Ticking or tapping sounds
Water heaters may have a heat trap or check type valve where the water enters or exits the water heater, often at the top of the water heater.
These valves are designed to stop water flow in a certain direction under some circumstances. They may be required by some building departments for energy conservation purposes.
The ticking or tapping noise is normal and people who are disturbed by the noise may replace the valves with other types or totally remove them. Note that water, when cooling down in some pipes will also make a similar sound.
Popping, cracking and gurgling sounds
Over time there is a build up of minerals on electric water heater elements and on the bottom area of gas water heaters. When the water becomes trapped under these build-ups and the water become hot from the electric elements or the gas burners under the tank going on, you may hear a popping, cracking or gurgling sound. These sounds get louder over time as the mineral build-ups get bigger and bigger.
Electric water heaters may also make a sizzling or hissing type sound.
Note that gas water heaters that are leaking or dripping water onto the gas burners may make similar sounds.
Flushing a water heater helps remove sediment build-ups and extends the life of a water heater
To reduce noise issues and extend the life of a water heater, you should follow the manufactures maintenance recommendations when flushing a water heater. The best source of information can be found on the water heaters’ manufacture website. It is important to follow their directions for safety purposes and to maximize the life of your water heater.
The most basic maintenance is flushing the water heater on a regular bases. How often you should do this will vary, depending on the chemical content and hardness of the water in your area, the amount of water you use and by the manufactures recommendations. Flushing every 4 to 12 months is common.
Banging, knocking and pounding noises, sometimes called “Water Hammer”
Usually it is not the water heater making this noisy. It generally relates to the homes’ water pipes and valves. These sounds can lead to damage to your pipes over time. ( READ MORE ON BANGING AND POUNDING NOISE )
Water at the base of a water heater, some times a sizzling or hissing sound
Possibility #1, leaking
If the water heater has a leak, there may be water standing or dripping in the area around the base. Should there be a sizzling sound but no water visible, you may still have a leak. The hissing or sizzling sound is that of dripping water on the burners or a small spray of water in the burner area.
Possibility #2, condensation is occurring
In the summer when you’re sitting outside on a hot day and having a cold glass of ice tea, you notice that water droplets are running down the side of your glass. This is condensate, moisture in the hot air hitting a cold surface.
A gas water heater may have moisture occurring at the base area do to condensate of the gas vapors hitting a cool service, therefore do not jump conclusions on the source of the moisture. It may be from a condensating issue and not a leak. There is a tendency for undersized water heaters and new energy efficient water heaters to have this issue.
A water heater pan under the water heater helps reduce damage to the platform from this issue.