Are Tankless Water Heaters Loud? The Real Answer Explained

If you’re thinking about going tankless, you’ve probably wondered: are tankless water heaters loud?

Tankless models have a lot going for them over traditional tank-style units. They’re more energy-efficient, take up less space, and you don’t have to worry about a tank leaking all over your basement. Check out our guide to the best electric tankless water heaters for top-rated quiet models.

But here’s what some people get wrong: tankless heaters aren’t silent. They do make noise, and over time, that noise can change. If things start sounding different, there might be a technical issue behind it.

The smart move is to get it checked early before a small problem turns into an expensive repair. If your unit keeps turning off, unusual noise could be pointing to the same root cause.

Are Tankless Water Heaters Loud?

Gas tankless water heaters can be as loud as 90 decibels when starting up and heating water. Once your tankless water heater has finished the initial ignition and reached a stable temperature, it’s generally not very loud.

A decibel meter is recommended to find out just how loud your water heater is. Let’s get into the details of the noise behind tankless water heaters.

What Is The Average Level Noise Of Tankless Water Heaters?

If you’re going to buy a tankless water heater, you must be wondering what level of noise you should expect from its regular operation. The most obvious comparison is with a traditional tank-style model.

When a tankless heater starts heating water, it makes some noises. It’s not something you should worry about because it’s very reasonable for a tankless water heater to start its operation with that type of loudness.

It has burner and blower motor features, and the same elements are present in tank-style heaters as well.

Tank-style heaters maintain the same level of noise throughout, whereas tankless heaters become less noisy once the constant temperature is reached. Most people with experience using both types don’t report any significant difference in noise levels.

As per reviews, tankless water heaters don’t get louder than your refrigerator during normal operation. They only reach the noise level of a refrigerator for a couple of seconds when the flue-purge is working at maximum speed.

A little noise from the shower in the next room can easily overwhelm the sound of your tankless water heater. This means you’ll only hear it working by paying close attention when no other appliances are running and no water is flowing.

Some manufacturers praise their products for how silent they’re, claiming noise levels won’t exceed 49 dB. The best products most commonly used produce noise between 45 dB to 65 dB, which is perfectly reasonable for a home appliance.

Common Causes Of Noise

When sophisticated machinery operates, it makes various types of noises, and the same is true for tankless water heaters. You shouldn’t get worried whenever you hear sounds from your unit because, as discussed above, all of them make sounds while working.

Even if your heater isn’t actively working, it can make noise due to the vacuum siphoning water, which causes a little vibration and sound. If you want to keep your unit working correctly, you should call a plumber periodically to check water line valves and prevent potential problems.

A widespread problem that can cause noise is a dirty flow sensor. Its job is to control the gas amount that the unit needs, and when it gets dirty, the unit may make unusual sounds.

If the ventilation is improper or somehow blocked, it can easily cause unusual loudness. If the pressure isn’t set to the right amount or the sensor is defective, you’ll likely hear a different type of noise.

You can check it yourself by using a decibel meter, and if the sound exceeds 90 decibels, you need to get it checked by a professional. If the sound is less than 90 dB, there’s nothing to worry about, though you can still get it inspected for your peace of mind.

You don’t need a special decibel meter if you’ve a smartphone, as you can easily download a free decibel meter app. Another common mistake people make is improper installation, which can cause noise when the heater touches the wall or other objects while vibrating.

Normal And Abnormal Noises That A Tankless Water Heater Can Make

If you’re not familiar with machinery, you might hear many types of noises from your tankless water heater and not know what they mean. Here is a breakdown of normal versus abnormal sounds to help you identify potential issues.

Tankless water heaters reduce the consumption of gas and electricity to keep a large amount of water warm in a tank, which eventually saves you money. However, the biggest concern about tankless water heaters is that they’re often installed inside bathrooms rather than in crawl spaces or basements.

On top of that, they’re noisy, and people are usually concerned about it, which brings them to the question: are tankless water heaters loud? Below are some of the noises you shouldn’t worry about.

Normal Noises

Clicking

If you hear your tankless water heater clicking on and off briefly, this is a typical sound that all units generate. It mainly occurs when the unit starts or stops working because of the installed flow switch that controls water flow.

If the clicking sound is continuous even without demand for hot water, the flow switch is likely damaged and needs replacement.

Rumbling

Whenever you turn the hot water tap on, the initial ignition sequence is usually very loud. Many models can reach 90 decibels at that moment, which is comparable to a jackhammer 50 to 60 feet away.

If you install your tankless water heater inside an insulated box, this sound reduces dramatically. However, if your unit makes rumbling noise constantly, you should get it checked by a professional.

Abnormal Noises

Groaning

If you’ve noticed your tankless water heater making groaning or moaning noise whenever you try to draw cold water by using an appliance near it, then probably your check valve is broken. If the check valve is broken, then your unit will make groaning noise because it creates a vacuum problem with the plumbing.

You need to keep in mind that cold water machines shouldn’t draw water from the water heater, but it’s entirely possible if the check valve is broken or not working correctly. A broken check valve can also contribute to low water pressure from your water heater.

Knocking

If you feel like there’s something inside your tankless water heater making a noise like knocking on the heater’s wall, the most probable cause is that the pipes are banging against the outer body. If the knocking sound comes whenever you start your heater and stops when it shuts down, then it’s probably the same reason described above, also called water hammering.

The knocking sound travels through water and pipes and echoes through the entire structure of the heater. You can fix it with a device that absorbs the shocks causing the water hammer, or you can use straps as stabilizers for the pipes.

Humming

If any component of your tankless water heater is loose, it will vibrate during operation and cause a humming noise. The heating unit is placed on one side, and if any part or element isn’t secured, you’ll hear the humming.

Although there’s nothing concerning or dangerous that you should worry about regarding this sound, it can be irritating and annoying. If you want to get rid of it, you just need to tighten up any loose component and that’s about it.

Sediment Buildup

One of the most common and concerning noises that tankless water heaters make is caused by sediment within the unit’s operational system. Water that we usually use for our heaters contains many agents such as magnesium, calcium, and more, and even though water doesn’t stay long in the system, these materials can still cause sediment deposits.

As a result, you can hear several types of noises like hissing, popping, and cracking, and that can be dangerous for your tankless water heater. When hot water contacts the sediment, it generates a popping sound, which happens because of the residue’s breaking.

Sediment isn’t something that will go away with the flow of water. All manufacturers and experts advise that you flush your tankless water heater every once in a while with a regular cycle.

The average should be twice or thrice a year, which is more than a healthy practice that will boost the life of your unit.

If you live in a region where the water is hard and contains higher mineral content, you should flush your heater monthly for better performance. Another option is adding a water softener to your system.

While a softener won’t eliminate all minerals permanently, it will improve performance and extend the time between sediment buildup issues. You can also try adding hydrogen peroxide to your water heater to break down deposits and reduce noise.

Understand The Workflow Of A Tankless Water Heater

We’re mentioning it again as a reminder that you should keep in mind that all tankless water heaters, whether brand new or older, make some noises, and you shouldn’t get worried about all of them.

The workflow of the tankless water heater is effortless, and you need to go through the basics of how tankless water heaters work to know all the usual sounds that your heater generates. The first step is to turn on the water tap connected to the heater for hot water.

The preinstalled flow sensor will detect the water flow and send its signals to the radiator to begin heating.

If your unit is gas-fired, the control panel will turn the fan on after receiving the signal from the flow sensor. It opens the gas valve and draws air in, which ignites the burner. Some homeowners wonder whether gas water heaters use electricity at all, and the answer is yes, for components like these.

From those flames, the heat exchanger heats the water that flows through its tubes. The water is then tempered by a mixing valve before you receive it at the faucet.

The water heats up according to the setting you’ve given the control panel. If the temperature falls short of or exceeds your desired setting, the panel automatically adjusts the mixing valve, gas valve, and water flow regulating valve.

If you understand this process, you’ll be able to identify each type of noise your working heater makes. You’ll also understand when a noise is abnormal and requires attention.

Groundwater Temperature Matters For Better Performance

There are several vital points to keep in mind while adjusting the temperature settings of your tankless water heater, and there are various aspects that affect your product’s life. The most important consideration is to know the temperature of groundwater where you live because it can have a significant impact on keeping the ideal temperature settings.

If you increase the temperature settings to the maximum level, it will decrease your heater’s lifespan. You can ask experts, or you can search online to know the temperature of your area’s groundwater before setting the thermostat.

If the groundwater temperature is moderate or warm, you won’t have issues with performance. But if the groundwater is cold, it will be harder for your unit to perform at its best.

Your heater will have to use more energy to reach the desired temperature. The higher the temperature setting, the shorter the lifespan of the unit.

It has been observed that tankless water heaters make less noise in areas where the groundwater temperature is moderate. If you live in an area with cold groundwater, consider boring deeper to reach a more moderate temperature level for improved heater performance and longevity.

What Is The Standard Temperature Setting?

If we talk about the ideal hot water temperature, there’s no such universal ideal because it varies from person to person and ultimately depends on your desire. As each person is unique, their physical structure and reaction to cold and warm are also unique.

Children and elderly individuals often prefer more heated water than younger ones.

What you can do is set a temperature that works as a standard according to your household requirements, which in normal conditions is typically 140 degrees Fahrenheit. That’s why most tankless water heaters also come with the same thermostat settings, also known as a universal standard.

If you’re more concerned about energy consumption and saving money, you should decrease that setting to 120 degrees Fahrenheit. Not only is 120F a safe temperature where you won’t feel much difference, but it also saves significant money and energy compared to 140F.

A reduced temperature also helps prevent sediment buildup, as more minerals pass through with the water flow. It reduces the chance of corrosion and lowers the likelihood of abnormal noises.

On top of all that, less temperature also reduces the chance of all types of abnormal noises. It can also save your money that you might spend on maintenance, which will be mandatory if you keep your heater at a higher temperature.

Just so you know, whenever you decrease the temperature of your tankless water heater’s thermostat by 10 degrees Fahrenheit, it saves you 5% on energy bills. Although most water heaters come with the thermostat settings at 140F, it’s not necessary to keep it at the same settings.

Advantages Of Tankless Water Heaters

There are many advantages of tankless water heaters, but the most prominent and famous one is that they’re compact and don’t take up too much space. On the other hand, traditional water heaters with tanks are getting bigger because, as per international standards, they must have thicker bodies and insulation.

If your house has an old construction, new traditional heaters won’t be able to fit where the same capacity old heater could. Even compact units like a 30-gallon gas water heater may struggle to fit in older spaces.

If you own a vacation home and go there once a year to spend your leisure time with your family, you must know how hard it’s to drain water from the heater with tanks before leaving. Not only does it take a lot of time in draining, but it’s also a massive water wastage.

On the other hand, you just need to unplug the tankless water heater and that’s about it.

Another fantastic feature of tankless water heaters is that they’re efficient and safe. For smaller applications, point of use water heaters are highly efficient and even quieter. If there’s a leakage, they don’t spill a massive amount of water as tank-type heaters do.

Plus, the exhaust and the air supply vents are sealed adequately in tankless heaters, so carbon monoxide can’t leak to harm anyone in your house because of back drafting. If you experience too much pressure in your water heater, that can also create unusual sounds and safety concerns.

There are a few things that you should keep in mind to get long-lasting and most efficient performance from your tankless water heater and avoid any unusual and abnormal noises. If you do a little maintenance like cleaning up the sediment buildup, then the life and performance of your unit will automatically increase.

The buildup can reduce the flow of water to approximately 0.3 GPM, and your unit will shut off.

What’s Special About Tankless Water Heaters

It’s easy to maintain tankless water heaters because they don’t require a lot of maintenance to keep from harmful noises, which can also harm your product. Besides, tankless water heaters don’t keep the water hot in the tank because they’re tankless, and you get the hot water instantly.

It takes about 10 to 20 seconds to heat water to your desired temperature. That’s much faster than how long a traditional hot water heater takes to heat up. Some of the latest tankless models even come with WiFi capability, allowing you to adjust temperature settings from your smartphone.

The most key feature that WiFi enables is that your unit can even identify the problem. If it’s related to some unusual noise, then you can fix it yourself or call a professional plumber to handle it.