Water Heater Noise: Why You Need to Listen

Updated
Categories Water Heating
A noisy water heater can be an early warning of trouble brewing. Here’s what it could mean.

Are you noticing strange noises coming from your water heater? Wondering what it could mean? Although not all sounds are due to malfunction, water heater noise may indicate a developing problem.

This is why it’s important to figure out what it’s trying to tell you and pinpoint the issue — before running out of hot water.


Causes and Noises

Here are the most common issues along with the sound your water heater is most likely to make.

1. Tank Build-Ups

Sediments, mineral deposits, and other build-ups may quickly cause trouble inside your water heater. Sediment is generally defined as any sort of material which settles inside your tank. It could be sand or other debris which enters the tank with the water, or minerals released as the water heats.

Sediment build-up can start out as a minor problem, only slightly decreasing your unit’s efficiency. However, as it accumulates it can cause clogging to the point you can’t even flush the tank — this could mean a replacement.

Rumbling

You’ll most likely hear this noise as the temperature increases within the tank. As it expands the water passes through the sediment — it’s this clash that causes the rumbling.

The sound tends to amplify as more sediment collects. If the noise has become very noticeable, build-up may have reached a critical level.

How to Fix It

Flush and drain your tank. You can use a deliming solution to help get rid of the sludge. If you don’t like the thought of using chemicals, try vinegar.

Popping

Popping noises are most often caused by limescale, a common problem in areas with hard water. The different minerals (calcium and magnesium) are found in the ground and absorbed by the water as it passes through.

While these minerals are required for our health, they can be harmful to a water heater. As the water is heated within the tank, the minerals separate and forms limescale.

Loose sediment on the bottom of the tank can also be a factor. Sometimes steam bubbles are formed underneath the sediment. As the water heats up, they burst, hence the popping noise.

How to Fix It

Try draining and flushing the tank through to remove any mineral sediment. If your tank has a heating element, descaling may limit further deposits.

Sizzling, Hissing, and Crackling

These are typical noises coming from an electric water heater — but they could also indicate trouble. As sediment builds up at the base of the tank, the lower heating element can become covered or buried.

When this happens, it’s unable to heat or function properly and starts making noise.

How to Fix It

What you need to do is drain the tank completely and remove the lower heating element. Soak the element in a descaling solution, then use a wire brush to gently remove any residue.

2. Fluctuations in Water Pressure

As the water pressure changes, you may notice a few noises. These are usually caused by the pipes and plumbing, not so much your water heater.

Ticking

A ticking noise is the most common sound caused by changes in water pressure. Many water heaters use water outlet and inlet nipples with heat traps. The nipples are what connects the plumbing to the unit — they essentially improve efficiency.

The heat trap can sometimes be the reason for ticking noises. If you suspect this is the cause, you can simply replace the nipples with a non-heat trap.

Pipes and plumbings are also notorious for making a few noises. As the water leaves the unit through the lines, they expand or contract as the water warms or cools.

When they expand, they could be rubbing against the framing of your house. Loose straps can also result in a ticking noise.

How to Fix It

Follow the sound and try to find the source. All you may need to do is tighten any loose straps. However, if the noise still occurs, you can install spacers which will prevent the pipes from moving.

Reducing the water temperature by a few degrees can also prevent the pipes from expanding too much. This is sometimes enough to eliminate any ticking noise.

3. Condensation Leaks

Condensation is usually found in gas-powered water heaters. As the cold water within a tank gets heated, it can cause a significant amount of condensation. New models even use this to their advantage — these are called condensing water heaters.

As the gas leaves the exhaust, it’s very hot. In condensing models, they reuse the condensation to further heat the tank. This results in less energy used and a much cooler exhaust which is better for the environment (1).

Sizzling

If you’re beginning to hear a sizzling noise from your gas-powered water heater, you may have a condensation problem. As the water heats and condensation is formed, it could be dripping down onto the burners, sizzling as it hits. This could indicate a leak within the tank.

How to Fix It

You can check the immediate area around the unit to see if there are any obvious signs of water. However, this should be a job for your plumber.

4. Restricted Water Flow

The valves on your water heater are what controls the water flow. If the flow is limited, you might be hearing a significant sound.

Screeching, Screaming or Singing

As the water tries to run through a small opening, you might notice a few screaming or screeching noises. Certain valves may be the source of this noise issue:

  • T&P relief valve: The temperature and pressure relief valve is also known as a safety valve. It allows the water to escape if the pressure becomes too high inside the tank. If you suspect this valve, cut the power to your heater and call a plumber.
  • Inlet valve: It could be because the inlet valve isn’t fully opened — this can greatly restrict the water flow. Check the valve and make sure it’s open all the way.
  • Valves and lines: If you’ve checked the above and still notice a few sounds, try inspecting the water lines and outlet valve. Check the lines for any flaws or kinks — the outlet valve should also be fully opened.

5. Water Source

Popping

An anode rod is an important component of the water heater — it prevents rust. If your local water supply is alkaline it could be causing a few problems inside your tank.

There are two main types of anode rod: magnesium and aluminum.

A popping noise is common if your water heater contains the aluminum type and is exposed to high levels of alkalinity. It’s thought this type of metal reacts with the pH level of the water, creating a noise.

How to Fix It

If the aluminum anode rod is the problem, replacing it with a magnesium version could be the best solution.

6. Water Hammer

Banging or Hammering

Loud noises like banging or hammering are usually caused when water is abruptly shut off. As it has nowhere to go this causes the water to flow backward in your system. The sound is often referred to as a Water Hammer (2).

It can potentially cause a water pipe to burst, creating a big problem in your home. It can also cause a few problems with your water heater.

Be aware

Pressure could build. There may even be enough force to expand the tank shell. Damage to the flue tube and deforming the tank are also possibilities.
How to Fix It

We suggest installing a water hammer arrestor (pressure reducing valve). It’s a device designed to protect your plumbing, pipes, and tank by absorbing the shock created by the water hammer.

Tankless Water Heater Noise

Tankless water heaters aren’t known to create noises like tank models. However, you may still hear a few pops or ticks.

Clicking is a common noise when the unit turns on and off. You might also hear various sounds if you live in a hard water area or if there’s a buildup within the unit.

How to Fix It

Regular maintenance should help you keep on top of any unusual sounds.


Humming a Tune

Water heater noises can be annoying or downright worrying. Knowing what they mean can help you track down the cause faster, saving you some time and putting your mind at ease.

Generally, regular upkeep of your water heater should reduce or eliminate most noises. It can also help to extend the life of your unit and even increase its efficiency.

What other noises have you heard coming from your water heater? Leave a comment in the section below and share your thoughts and concerns.

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About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.
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