Tankless Water Heater Cleaning

12February 2024


The Ultimate Guide to Tankless Water Heater Cleaning

Tankless water heaters are an efficient alternative to traditional tank-style heaters, providing hot water on demand and reducing energy consumption. However, to maintain their efficiency and prolong their lifespan, regular cleaning and maintenance are essential. This guide delves into the importance of tankless water heater cleaning, the signs that it’s time for a cleaning, and a step-by-step process to clean your unit effectively.

Why Clean Your Tankless Water Heater?

Over time, minerals from hard water can build up inside the tankless water heater’s heat exchanger, leading to inefficiency, reduced water flow, and even premature failure of the unit. Regular cleaning helps to:

  • Remove mineral deposits, ensuring optimal efficiency
  • Prevent corrosion and damage to internal components
  • Extend the lifespan of the unit
  • Maintain water quality and flow rate

Signs Your Tankless Water Heater Needs Cleaning

  • Reduced Water Flow: A noticeable decrease in water pressure or flow rate can indicate mineral buildup inside the heater.
  • Temperature Fluctuations: Inconsistent water temperatures or difficulty maintaining a steady hot water supply are common signs that cleaning is needed.
  • Error Codes: Many modern tankless heaters display error codes to alert you to potential issues, including the need for descaling or cleaning.
  • Noisy Operation: Unusual sounds coming from the unit can be caused by sediment rattling around inside.

How Often Should You Clean Your Tankless Water Heater?

The frequency of cleaning depends on several factors, including the hardness of your water, the amount of hot water you use, and the manufacturer’s recommendations. As a general rule, it’s advisable to clean your tankless water heater at least once a year. However, if you have very hard water or heavy usage, more frequent cleaning may be necessary.

Step-by-Step Guide to Cleaning Your Tankless Water Heater

Materials Needed:

  • White vinegar (approximately 4 gallons)
  • Submersible pump
  • Hoses to connect the pump to the water heater
  • A bucket

Cleaning Process:

  1. Turn Off the Power: Safety first. Turn off the power to your tankless water heater, whether it’s electric or gas.
  2. Close Water Valves: Close the cold water inlet and hot water outlet valves on the unit.
  3. Prepare Cleaning Solution: Fill a bucket with white vinegar. Do not use chemical descalers or cleaners unless recommended by the manufacturer.
  4. Connect the Pump: Use hoses to connect the submersible pump to the cold water inlet and another hose from the hot water outlet back into the bucket to create a closed loop.
  5. Circulate Vinegar: Turn on the pump and allow the vinegar to circulate through the unit for at least 60 to 90 minutes to dissolve and flush out mineral deposits.
  6. Flush the System: After descaling, disconnect the pump and flush the system with fresh cold water to remove any remaining vinegar and loosened deposits.
  7. Turn the Power Back On: Once the system is thoroughly flushed, you can turn the power back on.


Regular cleaning of your tankless water heater is crucial for ensuring efficient operation, prolonging the unit’s lifespan, and providing your home with a reliable hot water supply. By following the steps outlined in this guide, you can effectively clean your tankless water heater and enjoy the benefits of this efficient and convenient water heating system.

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