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Noisy Water Heater: Why is Your Water Heater Making Noise?

Noisy Water Heater

A noisy water heater is not uncommon, in fact, it can be extremely 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 noise, you should diagnose the problem as soon as possible to prevent an issue from worsening. Our guide will cover the seven most common causes of why your water heater is making unusal noises, and help you determine what you need to do to quiet things down.

Common Causes of a Noisy Water Heater


 
 

Mineral Deposit and Sediment Build-up

Popping Noise

If your electric water heater is making Popping noises, 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 or mineral deposit build-up.

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

Mineral deposit build-up, often called lime scale, is made up primarily of calcium and magnesium carbonate. Lime scale is part of the sediment, and 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 coat the inside of the tank and other components.

Sediment and lime scale will not only cause your water heater to be noisy, but they will also negatively impact the efficiency and life expectancy of your water heater.

Since all tank-style water heaters accumulate sediment over time, it's critical that they are flushed on a regular basis. Flushing your water heater will keep the level of sediment build-up to a minimum.

Installing a sediment filter can be extremely helpful as these filters greatly reduce the amount of sediment that comes in from your city or well water supply.

 
 
 

Sediment Filter

Dupont, WFPF13003B, Filter System, 3/4 in NPT, 5 gpm

This sediment filter made by DuPont will filter out sediment before it enters your water heater.

Another proactive method to protect your water heater is to install a water softener to help reduce the "hardness" of the water. You can read our extensive article about water softeners that covers several different types of systems and how they work. One of our favorites is the 3M Aqua-Pure Scale Inhibition System.

 

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Scale Inhibitor

3M Aqua-Pure Whole House Scale Inhibition Inline Water System AP430SS, Helps Prevent Scale Build Up On Hot Water Heaters and Boilers

The 3M Aqua-Pure Scale Inhibitor helps prevent lime scale build-up.

Rumbling Noise

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 within the tank is significant.

The rumbling 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.

You can attempt to flush your water heater, but it's not uncommon for the sediment to clog the drain valve and not allow the tank to empty. Read our article on how to unclog a drain valve to help you drain the tank.

Although, you should keep in mind that if it's been a long time since you've flushed your tank, you may cause more damage by doing so. Overtime, sediment will cause the steel tank to rust and eventually begin to leak. It's not uncommon for a neglected tank to begin leaking after being flushed.

Some homeowners choose to leave things as they are and simply wait until their tank leaks before purchasing a new water heater. If you choose to wait, we highly recommend purchasing a water alarm to alert you to the first signs of leakage. 50-gallons of water on the floor can do a lot of damage!

 
 
 
 

Water Alarm

Glentronics, Inc. BWD-HWA 00895001498 Basement Watchdog High Water Alarm, Multi

This inexpensive water alarm will alert you when your water heater begins to leak.

Crackling, Sizzling, Hissing or Popping Noise

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 within the tank has accumulated to this level, you should drain the tank and detach the heating element. Soak the element in vinegar and then use a wire brush to clean the heating element of lime-scale build-up. 

In some situations you may want to replace the heating element, but typically it can be cleaned and replaced.

 
 
 
 

Heating Element

Rheem SP10869MM Screw-In 240-volt by 4500-watt Element, Premium Resistored Stainless Steel

Heating elements are inexpensive and relatively easy to replace.


 

Valve Not Fully Open/Closed

Sizzling Noise

If you hear a Sizzling noise coming from your water heater, its usually an indication that the water flow is restricted. First, check the temperature and pressure relief valve, which is designed to let water out of the tank if there's too much pressure.

If any water is coming out of the T&P valve then you might have a serious problem. Shut the water heater down by turning off the power and water, and contact a professional plumber.

If your T&P valve looks fine, you can check the water valve leading to the water heater, and make sure its fully open. You could also check the valves on other waterlines and outlets, such under a sink.

 
 

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Water Pressure Fluctuations

Ticking Noise

A Ticking sound is often the result of pressure fluctuations within 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 you find that the heat trap is the source of the ticking you can replace it with a non-heat trap nipple. Keep in mind that there will be a small impact on the water heater's energy efficiency. 

 
 
 
 
 
 

Dielectric Nipples

Camco 10623 Dielectric Nipples

Switching to non-heat trap nipples can eleminate a ticking sound.

It's also possible that the Ticking sound could be coming from your household plumbing as the water travels to the faucet. Pipes expand and contract when hot water travels through them. This can cause the pipes to rub against loose straps or the wood framing.

To solve this problem, track down the point at which the sound is the loudest and secure the pipe or install plastic spacers. A simpler option may be to turn down the temperature of the water heater. Lowering the temperature, even by a few degrees, can help reduce the pressure and it may be enough to eliminate the ticking sound.

 

Condensation or a Leak

Sizzling Noise

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

If you have a leak inside the heater you could also hear a similar sound, but its more likely that you'll 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.

 

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Water Supply

Popping Noise

A Popping noise can occur if your water supply has a high PH level. This is a common problem in areas that have chlorine/chloramines within their water supply.

Chlorine has a PH level of 11.7, and if your water heater has an aluminum anode rod a chemical reaction called aluminum hydroxide can occur. When this happens, a gel-like substance forms and accumulates at the bottom of the tank.

This problem can be fixed by flushing and deliming your water heater's tank and replacing the aluminum sacrificial anode rod with one made from magnesium.

 
 
 
 
 
 
 
 

Magnesium Anode Rod

About Fluid | Magnesium Flexible Anode Rod Kit for Water Heaters | Teflon Tape | Easy-to-Follow, Step-by-Step Instructions | 44 Inches Long. (Without Socket and Cap)

If you live in an area where the water supply has a high PH level, you should have an anode rod made of Magnesium.


 

Water Hammer

Knocking Noise

If your hot water heater is making a knocking noise the problem could be serious. Surprisingly the problem may not actually be orginating from the water heater itself.

When the water flowing through your household plumbing is abruptly shut off, you may hear a noise that sounds like a Hammer or a Knock. With an abrupt stop of the water flow, the water has no where to go. So it attempts to return in the direction it came.

This is called water hammer, and it can be very destructive to your home's plumbing and may even cause a pipe to burst within your home which can cause serious water damage.

Water hammer can also create havoc with your water heater. The most common damage is an expanded tank shell, a collapsed flue tube, and/or inverted or deformed tank heads.

The solution to this very serious issue is not as difficult as you might think. A Water Hammer Arrestor can be installed to absorb the shock wave when the flow of water is abruptly stopped. When the shock wave reaches the device, an air chamber is ready to absorb the shock.

 
 
 
 
 
 
 
 

Water Hammer Arrestor

Sioux Chief Mfg 660-TK Female Swivel Ballcock Nut by Male Ballcock Thread Mini Rester

A Water Hammer Arrestor will absorb the shock within your water lines and protect your plumbing and water heater from damage.

 

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Electric Heating Element

Vibrating or Humming Noise

If your hot water heater is making a vibrating noise it could be the upper electric heating element. It could also resemble a Humming sound.  

Most electric water heaters use 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 it may cause the upper heating element to vibrate and create a humming noise. This is generally not harmful to the tank or the heating element, but it can be quite annoying.

Fortunately, this is an easy problem to fix. If you tighten the heating element you should be able to stop the noise. You'll need a special tool called a heating element socket. These are very inexpensive and nice to have on hand in case you ever need to replace your heating element.

 
 
 
 
 
 
 
 
 
 

Heating Element Socket

Camco 09953, TRV117743

This heating element socket will fit onto your 1/2" socket drive.


 

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