Tankless Water Heater Maintenance Tips

Routine Appliance Care Saves Money and Extends Service Life

Photo of Kelly R. Smith   by Kelly R. Smith

Typical tankless water heater anatomy
Typical tankless water heater anatomy
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This article was updated on 04/15/21.

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Tankless water heaters have long been a staple in Europe and Asia and are becoming more common in the US. There are many good reasons for this; the primary one is economic. Unlike a typical tank water heater, it only delivers hot water upon demand. Why store it in a bulky tank when you don’t have to? It’s one more way to increase your home’s energy efficiency.

It’s not a complete panacea though. Like any other appliance it requires periodic maintenance to operate effectively. Here are the top tankless water heater maintenance tips that the homeowner can do; make it a periodic DIY project. These generic instructions will work for most units but be sure to check your manual for any proprietary details.

Clean the Air Filter

  • Turn off and unplug the heater or isolate power by flipping the circuit breaker.
  • Find the air filter; remove it.
  • Inspect it carefully; a dirty filter will reduce performance.
  • Clean it with a soft-bristled brush using a mild solution of dish soap and warm water.
  • Rinse it well with clean water and dry it using a lint-free towel, and reinstall.

Clean the In-Line Water Filter

  • Find the in-line water filter at the cold-water inlet.
  • Close the cold-water supply valve to turn off the water supply to the unit.
  • Remove the filter.
  • Clean the filter by tapping it to dislodge sediment, run it under clean, clear water, and wipe it with a cotton swab.
  • Reinstall the filter.
  • Reopen the cold-water supply valve.
  • Check for leaks; tighten as needed.

Flush the Heater

  • Close the shutoff valves on both the hot and cold water lines.
  • Connect a hose from the outlet of a circulation pump to the cold-water service valve. Connect a drain hose to the hot-water service valve.
  • Pour 4 gallons of undiluted food-grade white vinegar into a clean 5-gallon bucket. Place both the drain hose from the hot water service valve and the pump supply hose (connected to the pump’s inlet) into the vinegar bucket.
  • Open the service valves on the hot and cold-water lines.
  • Turn on your pump allowing the vinegar to circulate throughout the heater at a rate of 4 gallons per minute.
  • Let it run an hour and then flush the system with clean, cold water to remove the vinegar and any loose minerals. To do this step, first remove the free end of your drain hose from your bucket, and then run it either to a convenient drain or to the outside. Next, close the cold-water service valve, open the cold-water supply valve, and then let the water flow through your heater for a minimum of five minutes. Next, close the cold-water supply valve, and clean the in-line water filter at the cold-water inlet on the heater to remove any loose deposits the filter picked up during the above process. Again, clean the filter by tapping it, running it under clean water and wiping it with a cotton swab. Finally, replace the filter.
  • Close your hot-water service valve, and then open both the cold and hot-water supply valves.
  • Disconnect all of the hoses, restore power to the heater, and turn it on.

These steps for tankless water heater maintenance should help you to keep your unit running efficiently and save you money by not having to hire a contractor. If you agree, please share with your friends and social media.

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About the Author:

Photo of Kelly R. SmithKelly R. Smith is an Air Force veteran and was a commercial carpenter for 20 years before returning to night school at the University of Houston where he earned a Bachelor’s Degree in Computer Science. After working at NASA for a few years, he went on to develop software for the transportation, financial, and energy-trading industries. He has been writing, in one capacity or another, since he could hold a pencil. As a freelance writer now, he specializes in producing articles and blog content for a variety of clients. His personal blog is at Considered Opinions Blog where he muses on many different topics.

4 Replies to “Tankless Water Heater Maintenance Tips”

  1. These heaters really make a lot of sense for someone like me that travels a lot. Why keep the fire burning with no one using it?

  2. When mine was installed the tech put an additional filter on the supply side since there are so many minerals in our water. An ounce of prevention I always say.

  3. I might add that if you get an on-demand water heater installed, you may need an electrician to beef up your circuits to handle the added electrical load.

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