Descaling a Tankless Water Heater

How to Descale a Tankless Water Heater

If descaling a conventional or tankless water heater isn’t already on your maintenance checklist, then you could be at risk of spending more money on your utility bill and shortening the lifespan of your heater.

What Is Descaling & Why Is It Important?

Your water heater accumulates hard mineral deposits over time, including lime, calcium, magnesium, and sand. “Hard water” is used to refer to high amounts of this mineral content. These particles stacked up on the water heater’s surface are called “scales.” The “scale build-up” will then precipitate and harden, creating a thick and chalky white coating that’s difficult to get rid of.

Descaling – also known as flushing – is the process of removing hard water from the inside of your conventional or tankless water heater, helping it to run smoothly and efficiently. Not taking care of this build-up at least once a year can lead to clogged pipes, drains, and faucets. Even worse it can overheat, create strange popping noises, or cause erosion. When it’s visible, it’s also not a pretty sight for you or your guests.

Do you have a household emergency? Contact CJ Plumbing & Heating to schedule service today.

What You Need to Descale Your Tankless Water Heater

If you take matters into your own hands, you’ll first need to get a water heating descaling kit and an isolation valve kit. That entails rubber gloves, a descaling solution, submersible pump, re-circulation bucket, connection hoses, lead-free inlet and outlet isolation valves, and a pressure relief valve. Retail value, these will run you at least $450 before taxes.

Fair warning: One slip-up can break your heater and cost more in the process to repair it. You can instead save time, money, and effort by hiring an award-winning plumbing company to descale your water heater.

How to Descale Your Tankless Water Heater

Descaling a tankless water heater requires more hands-on work than a conventional tank water heater. Tankless water heaters have a complex system of heat exchangers and burners that can be easily damaged if not handled with care and precision.

Below are the steps to safely flushing or descaling your tankless heater water. If ever in doubt, refer to the owner’s manual as this process can vary depending on the make and model.

  1. Turn off the power supply to your water heater via circuit breaker. Do this to prevent the risk of electrocuting yourself or others.
  2. Turn off the gas supply to your water heater.
  3. Turn off the main water supply to your water heater.
  4. Put on rubber gloves. Protective face gear is optional.
  5. Unscrew the pressure relief valve after the water has cooled down. It’s normal if you hear any hissing sounds.
  6. Pour the descaling solution and 1.5 gallons of water into the bucket. It should be half full. Then place it under the water heater.
  7. Connect the first hose to the inlet pipe. Connect the other end of the hose to the cold service outlet pipe.
  8. Connect the second hose to the hot service valve. Place the other end of the hose in the bucket. This will create a loop from the bucket through the tankless water heater.
  9. Open both the hot and cold service valves. Allow it to flow anywhere from 30 minutes to several hours, depending on the severity of the scale build-up.
  10. Close the cold service valve. Remove the hose from the cold service valve, then replace the service cap.
  11. Disconnect the first hose from the inlet pipe.
  12. Remove the hose from the bucket.
  13. Dump the solution down a drain. Alternatively, you can put the remaining solution in a hot water kettle. This will descale the kettle, improving the quality of water for your coffee and tea.
  14. Flush the tankless water heater with clean water for 5 minutes to remove any lingering descaling solution.
  15. Close the hot service valve. Disconnect the second hose and replace the service cap.
  16. Open the hot isolation valve.
  17. Turn on the gas, water, and power supply.
  18. Perform a test run to ensure that your tankless water heater is working properly.

For conventional water heaters, read our blog on how to flush a water heater.

Hire CJ Plumbing & Heating for Your Water Heater Maintenance

Water heater repair, replacement, maintenance – we do it all at CJ Plumbing & Heating.

Since 1992, Chicago homeowners have trusted us for our highly-reviewed, award-winning services while saving money in the process. Our friendly team of professional plumbers and technicians are licensed, bonded, insured, and trained to use state-of-the-art equipment that delivers red-carpet satisfaction every time.

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