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May 03, 2023

How to Descale Tankless Water Heaters | Navien

Unlike conventional tank water heaters, tankless water heaters heat the water on demand… every time you turn on a hot water faucet. Today’s tankless units can supply endless hot water during use, and not waste energy heating water when it is not needed. Manufacturers like Navien build tankless units that meet the demands of most applications, and plumbing contractors, builders, building owners, homeowners and engineers are adopting them as the standard in residential, commercial and multifamily projects.

What You Need to Know About Descaling a Tankless Water Heater

Although Navien tankless water heaters normally provide many more years of reliable service compared to a conventional tank water heater, like all water heating products they do require some routine maintenance. It’s important to follow through with an annual maintenance regimen, which should include “descaling”. Descaling is needed, because much like removing the lime and minerals from a coffee maker, the waterways of a tankless water heater will build up similar mineral deposits. Removing excess mineral deposits is important, because they can erode and clog the walls inside your heat exchanger, reducing efficiency, reducing flow, lowering the overall performance, and potentially causing premature failures.


How Often to Descale a Tankless Water Heater

The higher the level of mineral content in your water, the higher the set water temperature, and the more hot water your home uses, the more often you will need to have your tankless water heater descaled. This can be done by a professional or by yourself, if you possess the right equipment, materials and skills. Navien recommends descaling a tankless water heater at least once a year, but that frequency can vary based on the previous factors.


DIY Descaling

Descaling a tankless water heater requires the following equipment and materials:

  • An approved tankless water heater descaling solution, or household white vinegar*
  • Drain hoses (double ended wash machine hose)
  • A submersible pump
  • A 5-gallon collection bucket

Some descaling chemical companies sell the above components as a kit, or individual items may be purchased separately.

Note: *You can use an approved chemical or vinegar to flush and clean your tankless water heater.  Follow all safety requirements and manufacturer directions with chemicals, and after cleaning always flush with fresh water for a minimum of 10 minutes.

You can also get our written instructions on the Navien product downloads page located here.


plumber descaling a tankless water heater

Pros & Cons of Descaling Your Own Tankless Water Heater

For some individuals, there are a few advantages to descaling your tankless water heater on your own (cost savings, convenience) but be sure to weigh the downsides as well. Descaling a tankless water heater requires someone with at least cursory experience with plumbing tools and equipment. Plumbing professionals will be able to descale, along with performing any other required tankless water heater maintenance or service. Professionals have all the tools, test equipment, and experience to perform service in less time than most end users. Also, if service is done incorrectly and the water heater is damaged, you could void the warranty. It’s for these reasons that Navien recommends hiring a professional to descale your heater.


Professional Descaling

The cost of descaling (flushing) a tankless water heater can vary depending on many factors. To get a quote from a Navien service provider in your area, visit the find a service provider page.


What Happens if You Never Descale Your Tankless Water Heater?

Neglecting the descaling routine with your Navien tankless water heater can lead to serious problems over time. Buildup of mineral deposits can cause damage to your heat exchanger and may interfere with normal heating. Also, your heat exchanger could malfunction and overheat the water in your system and cause damage and premature failure to your tankless water heater.


Prevent Scaling with PeakFlow

Navien’s PeakFlow scale prevention system is an advanced, chemical-free water treatment system that prevents scaling before it starts.

Learn more about tankless water heater maintenance or find a service provider to get started.

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