How Noisy Is a Tankless Water Heater

How Noisy Is a Tankless Water Heater

Tankless water heaters are loaded with benefits, but being the quietest appliances in your home isn’t one of them. It doesn’t mean that tankless water heaters are loud; it just means that some noises are going to be heard when the tankless water heater is running.

What’s to say about the average level of noise for tankless water heaters?

Many customers wonder about the level of noise to expect from a tankless water heater. It counts a lot when comparing to traditional water heaters with tanks before choosing between the two.

We should start by noting that tankless water heaters are making a noise when starting and heating water. It’s not a noise to worry, but one that it’s reasonable and expected.

First of all, a tankless water heater features a blower motor and a burner, and nothing else could make a noise. The power vented traditional tank-style water heaters present the same elements, just that you know. Customers of both tankless and tank-style water heaters didn’t report significant differences between the two styles, in terms of noise.

An excellent tankless water heater isn’t louder than your refrigerator nor a snoring mouse in the other room. As a matter of fact, a shower in the next room may easily cover the sound of your tankless unit.

However, tankless water heaters can get noisy if the flue-purge at the end of the burn as the blower is working on maximum speed for a couple of seconds. Only then, your tankless water heater can get as loud as the refrigerator in the next room. For example, if you installed your gas tankless water heater in the basement, close to the master bedroom, and with the vent 5′ from the window, you will be able to hear the unit from your bedroom only if it’s dead-quiet in your home. No water is running, and no other appliances are making any sound, and only if you’re really paying attention to the unit. Even so, you may only notice the slight sound of the flue purge cycle that comes through the window.

Most of the time, a tankless water heater is as loud as an electric can opener or a computer fan. Some manufacturers really praise their products for being quiet, with a noise level of 49db for most models. You can also find tankless water heaters that present a range of 45 to 65db for the noise level. It’s perfectly honest to say that a direct-vent blower on the tankless unit will be less loud when running the minimum 19,900BTUs, as opposed to when it’s burning the maximum 199,000BTUs.

If you’re only checking the numbers from the manufacturers, you should take the info with a grain of salt. A 49db noise rating may be just another marketing strategy, reflecting the noise level at the lowest setting for the unit.

What are the common causes of noise coming out of your tankless water heater?

Anytime the noise happens when the tankless water heater isn’t running should be a reason for concern. Sometimes, it may be a vacuum siphoning water away from the unit and leading to a big noise and even vibration. Most of the time, you should give the plumber a call to check the water heater. A valve in the water line could be an easy fix when plumbing fixtures alter the water flow to the tankless water heater.

A messy flow sensor (controlling the amount of gas sent to the tankless unit) can also cause a loud noise. Blocked or inadequate ventilation and even defective/poorly set pressure valve can make your tankless water heater get loud.

As you can see, there are many possible causes for the noise, which is why you should check with a plumber for the diagnose and fixing of the problem.

Many aspects affect the level of noise for your tankless water heater, with the installation being one of them. It counts a lot if you mounted the unit right on the wall or enclosed in a protective box. If your water heater is installed close to a window, the chance of hearing it when it ignites is higher.

You need to see if the noise happens when the unit is heating the water, or if it’s the vibrations of the water heater against the wall/echoes within the box. One solution for absorbing the sound and lower the vibrations/echoes is to put some rubber mat or foam between your tankless unit and the wall. When the unit is enclosed in a box, you may very well insulate the inside of the box with materials used in the auto industry for audio insulation.

What noises should worry about you?

A noisy water heater isn’t something you never see. But you need to make the difference between the standard and abnormal noises for your tankless water heater.

Here are some noises that require your attention:

  • Popping

When your tankless unit makes a popping sound, the sediment build-up is the leading cause. Even if the water only goes through the tankless system and doesn’t have time to affect it, it still contains minerals that can lead to corrosion. It’s only a matter of time until sediment will build-up along with the system.

When the water gets blocked under the sediment, the popping sound will be heard. Mineral deposit build-up (mainly made of magnesium and calcium) is a constant problem in areas with hard water. Apart from the annoying noise, the mineral deposit will also affect the performance of your tankless water heater. The unit will struggle more, which can only alter its performance and durability.

You need to flush the unit at least once a year, but also to install a water softener if the hardness of water is high.

  • Sizzling, hissing, crackling

It’s the sediment build-up that may bury the heating elements inside the electric tankless water heater. In this case, you need to detach the heating element, using a wire brush and vinegar for cleaning and eliminating the build-up.

  • Sizzling

The unit may present some sort of blockage for the water flow. Take a look at the pressure relief and temperature valve and see if it’s too much pressure.

  • Ticking

Pressure fluctuations may lead to a ticking sound, and you should check the elements of the system for solving the problem.

You can never know too much about a tankless water heater!

Tankless water heaters aren’t very loud nor very quiet, but you do need to learn the difference between regular and abnormal noises. If you’re not good with words, you can always record your tankless water heater so that the plumber hears for himself the sound you’ve been talking about.

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