How to Reduce Noise From a Tankless Water Heater

Regardless of what you may have heard, tankless water heaters can get noisy. Even though those noises don’t always indicate a problem with the heater, you should determine the cause of the sound and address any underlying issues.

To reduce noise from a tankless water heater, it typically requires flushing the system with vinegar, tightening any loose parts, or making sure that inlet and outlet valves are fully open. Fortunately, you can perform these maintenance services on your own, eliminating the need for a plumber.

Reduce Noise From a Tankless Water Heater

This article will detail the three steps required to reduce the noise from a tankless water heater, followed by a discussion regarding solutions to other common problems associated with these units. 

For reducing noise from regular water heaters, read my guide.

Identify the Source of the Noise

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The first thing you are going to want to do is to identify the source of the noise. Identifying the sound’s location will help you determine the next step to take to reduce or eliminate the problem.

Typically, your tankless water heater makes noise for one of five reasons, or a combination thereof. Those reasons include loose parts, restricted water flow, sediment buildup, water pressure fluctuations, or vibrations.

The symptoms for each problem include:

  • Loose parts: Humming or rattling noises from your tankless water heater usually indicate your system has loose parts.
  • Restricted water flow: Screeching sounds are a tell-tale sign that your unit’s water flow has become blocked.
  • Sediment buildup: You will typically hear cracking or hissing noises when you have sediment buildup in your systems. Additionally, in extreme cases, you can hear popping sounds as the sediment begins to break from the heat.
  • Water pressure fluctuations: A ticking sound is the most common noise caused by changing water pressure.
  • Vibrations: A ticking sound is the most common noise caused by changing water pressure.

Each of these problems has its unique solution, as we will discuss below. 

Apply the Proper Corrective Action

Depending on the source of the noise, you will want to employ one of the following corrective actions:

  • Noises caused by loose parts: Tighten any loose pieces you discovered in step one using an appropriate wrench or socket. It is crucial that you accurately identify all loose parts as your system can sustain permanent damage depending on the particular parts affected.
  • Noises caused by restricted water flow: Check to ensure the water inlet and outlet valves are in the fully opened position. If not, rotate the taps counterclockwise until fully engaged. If the sound continues, you may need to have a plumber inspect your water lines and the temperature and pressure relief valve.
  • Noises caused by sediment buildup: Sediment doesn’t go away on its own. You will need to flush the system using vinegar to remove any sediment buildup. In extreme cases, the sediment buildup can bury the heating element inside electric tankless water heating systems. In that instance, you will need to detach the heating element from the unit and clean it using a wire brush and vinegar.
  • Noises caused by water pressure fluctuations: Try to trace the sound’s source and tighten any loose straps holding down your pipes. You can also install spacers between the pipes and the walls to muffle any noises.
  • Noises caused by vibrations: If the system is mounted directly to the wall, you can install a rubber or foam mat between the system and the wall. If the unit is in an enclosed case, you can insulate the inside of the case using audio insulation designed for automobiles. 

Take Preventative Measures to Prevent Future Noises

  • Noises caused by loose parts: Periodically check your tankless water heating system for any parts that may have worked loose over time.
  • Noises caused by restricted water flow: Make sure the inlet and outlet valves are fully opened at all times.
  • Noises caused by sediment buildup: You should flush your water heating system once a year. However, if your local water supply is hard, you might need to flush your system more frequently. A second, more costly option is to install a water softener system between your water supply and the water heater. You still might need to flush your system periodically, but using this makes that task a whole lot easier.
  • Noises caused by water pressure fluctuations: Periodically check for any loose straps on pipes connected to your tankless water heating system. Additionally, you might consider going ahead and installing spacers to the pipes before noise becomes an issue.
  • Noises caused by vibrations: You should consider installing a mat or audio insulation when installing your water heating system instead of waiting until the sound becomes an issue. 

Solutions to Other Tankless Water Heater Problems

Water Heater

You may experience issues with your tankless water heater not related to noise that will need to be addressed as they arise. Some common problems you might encounter with your tankless water heating system include exhaust blockage, ignition failure, overheating, and system overload. 

Exhaust Blockage

If our unit’s control panel displays an error code indicating an obstruction, your unit is experiencing a problem with its venting. Fortunately, fixing this problem is relatively simple.

To begin, you need to check all the vent pipes to make sure they are appropriately connected. Additionally, check to make sure nothing is blocking the exterior vents that aren’t blocked by bird nests, tree branches, or other obstructions. If so, remove those obstructions, making sure nothing falls down the vent pipes. 

Ignition Failure

If your system fails to ignite, make sure your gas and water valves are fully open. If not, rotate the tap handles all the way counterclockwise. Additionally, if your unit uses propane, make sure your tank isn’t empty. Likewise, if your system uses natural gas, make sure that your home’s gas hasn’t been turned off by your provider.

Likewise, if the system is electric, make sure the unit didn’t accidentally become unplugged. If not, check to see if the cord has become disconnected from the heating unit. Likewise, check for any kinks in the electric cable that might indicate internal breakage.

If those steps fail to correct the issue, you may have a problem with the unit’s ignition pack. In that instance, you will probably need to contact a licensed plumber to fix the problem.

Likewise, if you suspect there is a problem with your unit’s gas supply, it is best to contact a licensed professional. Gas is incredibly dangerous, particularly if you don’t have the proper equipment to test the system after making any repairs. 


Tankless water heaters are prone to overheating, particularly if multiple hot water sources are used simultaneously. If your system overheats and shuts down, check the temperature setting. Tankless water heaters operate best at 120°F (48.9°C) If it continues overheating, you should contact a licensed plumber to check the system for mechanical problems. 

System Overload

Depending on your unit’s capacity, you may experience a system overload if you are using too many hot water applications at the same time. For example, washing dishes while someone is taking a shower can put too much of a burden on your water heater.

If this happens, you should either reduce the number of simultaneous applications or install a larger unit. Likewise, you might consider installing additional units throughout your home to decrease the load on any single unit. 

The Wrap Up

Tankless water heating systems are an excellent investment for your home. They are energy efficient, save space, and provide a near-endless supply of on-demand hot water.

If you have a tankless water heating system or are considering installing one, you might consider bookmarking this article for future reference. 

Also read: Boiler Making Noise? Here’s what to do

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