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Noisy Water Heater: What are the Causes?

Noisy Water Heater

A noisy water heater is not uncommon, in fact, it can be very annoying, especially if the tank is located in your living space. Some of the noises that you hear could indicate a problem, and others may not be anything to worry about. If your water heater is making noises, you should diagnose the issue to prevent it from getting any worse. Here are some possible causes:

Noisy Water Heater: 6 Causes

Cause #1: Mineral Deposit and Sediment Build-up

If your water heater is making a Popping sound, the cause is likely from sediment build-up. Sediment is any solid material that collects at the bottom of your tank. It  can be sand or other debris that comes in with the water supply.

The popping sound you hear is caused when water becomes trapped below the sediment. As the water heats, steam bubbles develop and eventually explode.

Mineral deposit build-up, made up primarily of calcium and magnesium carbonate, is part of the sediment, and it is especially a problem in areas that have “hard” water. It occurs when the minerals separate from the water during the heating process, and then scale the inside of the tank. The build-up of minerals will not only cause noise, they will also negatively impact the performance and life expectancy of your water heater.

To prevent and remove mineral build-up, treat the water with a water softener, this will help reduce the “hardness” of the water, and also eventually eliminate the noise. Click HERE to read our article on protecting your water heater from hard water. It is written from a tankless viewpoint, but the concepts are the same for tank style water heaters.

Every water heater will accumulate sediment over time. Regularly flushing your water heater will keep the level of sediment build-up to a minimum, as well as ensure that it doesn’t interfere with performance. We recommend installing a sediment filter. 

If a water heater is not regularly flushed, sediment can build-up to the point where it can no longer be removed by flushing. When you hear a Rumbling sound, it’s a good indication that the sediment build-up is significant. This sound is caused when the expanding hot water escapes from sediment at the bottom of the tank. Although, this situation isn’t dangerous, it is a sign that your water heater’s efficiency has decreased. Attempt to flush your water heater. If this doesn’t work then you may want to consider purchasing a new one. It will only be a matter of time before the tank will rust and begin leaking.

With electric water heaters, sediment build-up can bury the lower heating element, when this happens a Crackling, Sizzling, Hissing, or Popping sound can be heard. If the sediment has built to this level, you should drain the tank and detach the heating element. Use a wire brush or vinegar to clean it and remove any build-up.

If you are unable to drain your water heater, or choose to wait until your water heater tank leaks, this video can be a resource to help you spot a leak:

Cause #2: Valve Not Fully Open/Closed

If you hear a Sizzling noise coming from your water heater, it is usually an indication that there is a restriction of water flow. First check the temperature and pressure relief valve, which is designed to let water out of the tank if there is too much pressure. If any water is coming out of this valve then you might have a problem. Shut the water heater down by turning off the power and water, and contact a professional plumber.

Next check the water valve leading to the water heater, and make sure it is fully open. You could also check the valves on other waterlines and outlets, such under the sink.

Cause #3: Fluctuations in Water Pressure

If you hear a Ticking it is a result of pressure fluctuations in the plumbing. In order to comply with many of the utility incentive programs, many water heaters have heat traps built into the nipples where the plumbing connects to the heater. If the heat trap is the source of the ticking, it can be removed as they are not necessary. However, there will be a small impact on the water heater’s efficiency.

Another possibly could be to check the plumbing pipes. As they leave your water heater, they expand and contract when hot water is drawn from the tank, causing them to rub against loose straps or wood framing. This can also result in a Ticking sound. To solve this problem, track down the point at which the sound is the loudest and secure the pipe or install plastic spacers. Turning down the temperature of the water heater, even a few degrees, will help reduce the pressure.

Cause #4: Condensation or a Water Heater Leak

If you notice a Sizzling sound with your gas hot water heater when the burner is ON, it is likely a condensation issue. Condensation can form and drip onto the hot burner components, creating a sizzling sound.

If you have a leak inside the heater you could also hear a similar sound, but it is more likely that you will hear the sizzling even when the burner is OFF. Look for water around your water heater to see if you can spot a leak. If you’re concerned about any sizzling sounds coming from your water heater call a professional plumber.

Cause #5: Water Supply

Sometimes a Popping noise can also occur if your water supply has a high PH level, and your water heater is outfitted with an aluminum anode rod.

If this is the case, simply change the aluminum sacrificial anode rod with one made from magnesium. Then use a nonacid lime descaler to help break down the mineral build-up within your tank.

Cause #5: Water Hammer

When the water flowing thru your household plumbing is abruptly shut off, you may hear a noise that sounds like a Hammer or a Knock. With the abrupt stop to the water flow, the water has no where to go and attempts to return in the direction it came. This is called water hammer, and it can be very destructive.

Although, water hammer does not originate with your water heater, it could cause harm to your unit. The most common issues are: Expanded tank shell, collapsed flue tube, inverted or deformed tank heads. It also could cause a pipe to burst within your home creating serious water damage.

A Water Hammer Arrestor can be installed which will absorb the shock wave when the flow of water is abruptly stopped. When the shock wave reaches the device, an air chamber will absorb the shock.

Cause #6: Electric Element

If you hear a Humming noise, it could be the electric heating element. There are two heating elements, one located near the top of the water heater, and one near the bottom. When the cold water flows into the tank, and around the upper heating element, the element can vibrate, which in turn creates the humming noise. The noise is generally not harmful to the tank or the element, but it can be quite annoying. If you tighten the heating element, the noise should stop.