How to Flush a Tankless Water Heater: StepbyStep Guide for Optimal Performance

How to Flush a Tankless Water Heater?

To flush a tankless water heater, you will need the following items: isolation valves, channel locks, one gallon of food-grade white vinegar, a submersible sump pump, two hoses, and a bucket (optional gear includes rubber gloves and old clothes).

Start by turning off the power supply and closing the shut-off valves on the water lines.

Drain the hot water from the tankless water heater by turning on the small red drain valve.

Clean the prefilter by unscrewing it and checking for scale buildup.

Attach hoses to the cold and hot drains, making sure they are screwed tightly.

Submerge the sump pump in vinegar and let it run for an hour.

Remove the hoses from the bucket, screw the drain caps back on, and turn the water lines and gas back on.

Dispose of the vinegar and scale mixture properly.

Finally, let the cold and hot water run for 5 minutes to flush out the vinegar completely.

Flushing a tankless water heater should be done at least once a year to maintain optimal efficiency and extend the lifespan of the unit.

Key Points:

  • Gather materials:
  • isolation valves
  • channel locks
  • one gallon of food-grade white vinegar
  • submersible sump pump
  • two hoses
  • optional gear such as rubber gloves and old clothes
  • Turn off power supply and shut-off valves on water lines
  • Drain hot water from the tankless water heater by opening small red drain valve
  • Clean prefilter by unscrewing it and checking for scale buildup
  • Attach hoses to cold and hot drains tightly
  • Submerge sump pump in vinegar and let it run for an hour


Did You Know?

1. Did you know that tankless water heaters were first developed in Europe in the 1920s but only gained popularity in the United States much later?
2. A little-known fact is that tankless water heaters are typically more energy-efficient than traditional tank-style heaters, as they only heat water on-demand instead of continuously heating a large storage tank.
3. Tankless water heaters can last up to 20 years, which is significantly longer than the average lifespan of traditional water heaters. This durability is due to their design and the absence of a storage tank, which eliminates the risk of corrosion and leakage.
4. An interesting feature of tankless water heaters is their ability to provide a continuous supply of hot water, without the risk of running out. This is because they heat water as it passes through the unit, ensuring a constant flow of hot water for as long as needed.
5. Tankless water heaters are known for their compact size, which allows for flexibility in installation. However, it is crucial to consider factors such as the gas or electric requirements and the right capacity for your household needs.

Importance of Flushing a Tankless Water Heater

Flushing a tankless water heater is crucial maintenance that should not be overlooked. Over time, harmful scale buildup can accumulate inside the tankless water heater, leading to various issues. Flushing helps remove this scale buildup, ensuring optimal performance and preventing early breakdowns.

When scale builds up inside the tankless water heater, it can cause problems such as:

  • No hot water
  • Long wait times for hot water
  • Decreased water pressure
  • Fixtures acting up
  • Error codes on the tankless status screen
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These issues can disrupt the normal functioning of the water heater and inconvenience the household. Flushing is an effective solution to avoid these problems and maintain a reliable supply of hot water.

Performing a thorough flushing at least once a year is highly recommended. However, households with hard water may need to flush their tankless water heaters more frequently, as hard water contains higher mineral content that can contribute to scale buildup.

Internal and External Maintenance for Tankless Water Heaters

When it comes to maintaining a tankless water heater, it is essential to understand the difference between internal and external maintenance.

Internal maintenance involves cleaning the parts of the tankless water heater that come into contact with water, such as the pipes and heat exchanger. Flushing the tankless water heater is an important process that should be carried out to remove any scale buildup that can accumulate over time. This helps improve the efficiency and longevity of the water heater.

On the other hand, external maintenance should be left to a professional plumber. It involves inspecting and maintaining external components, such as the venting system, gas connections, and seals. By having a qualified plumber perform these tasks, you can ensure that all external components are in good condition and functioning properly, reducing the risk of any potential damage or malfunction.

Remember, regular maintenance of both internal and external components is crucial for the proper operation of your tankless water heater.

Necessary Tools for Flushing a Tankless Water Heater

Before beginning the flushing process for your tankless water heater, it is important to gather the necessary tools and equipment. These items will not only make the flushing process more efficient but also help you achieve optimal results.

Here are the tools and items you will need:

  1. Isolation valves: These valves are essential as they allow you to isolate the water heater from the water supply. This makes the flushing process easier and safer.

  2. Channel locks: These adjustable pliers are a must-have tool for loosening and tightening connections during the flushing process.

  3. One gallon of food-grade white vinegar: Vinegar is an effective cleaning solution that helps in removing scale buildup inside the tankless water heater.

  4. Submersible sump pump: A sump pump is required to circulate the vinegar through the tankless water heater, ensuring thorough cleaning of the internal parts.

  5. Two hoses: These hoses are necessary to connect the water heater to the sump pump and direct the vinegar solution throughout the flushing process.

  6. Bucket: A bucket is needed to contain the vinegar solution while flushing the tankless water heater.

For your convenience and safety, it is also recommended to have optional gear such as rubber gloves and old clothes to protect yourself from any potential splashes or spills.

  • Isolation valves
  • Channel locks
  • One gallon of food-grade white vinegar
  • Submersible sump pump
  • Two hoses
  • Bucket

Tip: Ensure you have all the required tools and equipment before starting the flushing process for your tankless water heater.

Step-By-Step Guide for Flushing a Tankless Water Heater

To ensure a successful flushing process and maintain optimal performance of your tankless water heater, follow these step-by-step instructions:

  1. Turn off the power supply to the tankless water heater and close the shut-off valves on the water lines. This will prevent any accidents or water flow during the flushing process.

  2. To drain the hot water from the tankless water heater, locate the small red drain valve and turn it on. Allow the water to drain completely.

  3. While the water is draining, take the opportunity to clean the prefilter. Locate the prefilter on the bottom of the tankless unit, unscrew it, and check for any scale buildup. Clean the prefilter using a brush if necessary.

  4. Attach the hoses to the cold and hot drains, making sure they are securely screwed in place to avoid any vinegar spraying out during the flushing process.

  5. Place the submersible sump pump into the bucket and pour the one gallon of food-grade white vinegar into the bucket until the pump is submerged.

  6. Turn on the sump pump and let it run for about an hour, allowing the vinegar to circulate through the tankless water heater and clean the internal components.

  7. After an hour, remove the hoses from the bucket, screw the drain caps back on the cold and hot drains, and turn the water lines and gas back on.

  8. Dispose of the vinegar and scale mixture properly, following any local guidelines or regulations for chemical disposal.

  9. To remove any vinegar residue from the tankless water heater, let the cold and hot water run for approximately 5 minutes. This will flush out any remaining vinegar and ensure that your water heater is back to normal operation.

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Benefits of Regular Flushing for Tankless Water Heaters

Regular flushing of a tankless water heater offers several benefits that contribute to its optimal performance and extended lifespan. Here are some key advantages of regular flushing:

  • Prevents mineral and sediment buildup: Flushing helps remove the scale buildup caused by minerals and sediment in the water. By eliminating this buildup, the water heater can operate more efficiently, delivering hot water faster and at a more consistent temperature.

  • Maintains optimal efficiency: Removing scale buildup allows the tankless water heater to maintain its maximum efficiency, helping you save on energy costs over time.

  • Extends the lifespan of the unit: Flushing a tankless water heater regularly can significantly extend its lifespan. By preventing the accumulation of scale and other deposits, the water heater is less prone to breakdowns and malfunctions.

  • Ensures a reliable supply of hot water: Flushing helps avoid common issues such as no hot water, decreased water pressure, and fixtures acting up. By maintaining a clean and properly functioning tankless water heater, you can count on a consistent supply of hot water whenever you need it.

6. Professional Assistance and Additional Considerations for Tankless Water Heater Flushing

While the flushing process for a tankless water heater can be done as a DIY project, it is important to consider professional assistance if the problem persists even after flushing. A qualified plumber can diagnose any underlying issues and provide appropriate solutions.

It is worth noting that lack of maintenance in a tankless water heater may lead to potential damage during the flushing process. If the water heater has not been regularly maintained, it is recommended to seek assistance from a professional to avoid any further complications.

Flushing a tankless water heater is a crucial maintenance task that helps remove harmful scale buildup and ensures the optimal performance of the unit.

By following a step-by-step guide and using the necessary tools, you can extend the lifespan of your tankless water heater and enjoy a reliable supply of hot water for years to come.

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Regular flushing is essential to:

  • Prevent mineral and sediment buildup
  • Maintain efficient operation
  • Avoid potential malfunctions

Don’t forget to consult a professional if needed and always prioritize safety during the flushing process.

Frequently Asked Questions

Can I flush my tankless water heater myself?

Flushing your tankless water heater can be done by yourself if you follow the proper instructions and take necessary precautions. However, it is crucial to be aware that the internal process of flushing deals with delicate parts such as pipes and heat exchangers within the unit. Therefore, if you are not confident in your ability to handle these components, it would be best to consult a professional plumber for the task. They possess the expertise to perform external maintenance on your tankless water heater, ensuring the intricate parts are cleaned appropriately and maintaining the longevity of your system.

Do tankless water heaters need to be flushed?

Yes, tankless water heaters do require regular flushing as part of their maintenance. Similar to tank units, tankless water heaters should be flushed at least once a year to remove any sediment buildup and ensure optimal performance. However, homeowners residing in areas with hard water should consider more frequent flushing, potentially every six to nine months. This is necessary due to the higher concentration of minerals like magnesium and calcium present in hard water supplies, which can accumulate more rapidly in the unit and impair its efficiency if not addressed regularly.

How long does it take to flush a tankless water heater?

The process of flushing a tankless water heater typically takes approximately 1-2 hours to complete. Although it may seem like a time-consuming task, it plays a crucial role in maintaining the efficiency and effectiveness of the system. By periodically flushing the tankless heater, you can prevent the buildup of scale and ensure its longevity.

What happens if you don’t flush your tankless water heater?

If you neglect to flush your tankless water heater, mineral deposits can accumulate over time. These deposits can lead to a potential obstruction within the unit, hindering the heating process. Furthermore, this build-up can also cause fluctuations in your hot water supply and lead to the overheating of the system, thereby impacting its overall efficiency. It is crucial to regularly flush your tankless water heater to avoid these issues and maintain its optimal performance.

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