How To Descale A Tankless Water Heater?

Tankless water heaters are a great investment for homeowners to get hot water on demand. They are known for their efficiency and longevity. 

However, a tankless water heater requires regular maintenance to keep its efficiency for years. If you don’t flush the tankless water heater, mineral deposits will restrict the heat exchanger. 

As a result, you will experience tankless water heater problems like fluctuating water temperature.

To avoid such operational problems, flushing the tankless water heater is a must. 

And this guide will walk you through a step-by-step guideline to learn how to descale a tankless water heater like a pro. 

Without further ado, let’s dive in.

Table of Contents

• What Are  TheTools & Equipment You Need To Descale A Tankless Water Heater?
• How To Descale A Tankless Water Heater?
  • 1. Preparation:
  • 2. Drain Excess Water:
  • 3. Set Up the Pump:
  • 4. Add Descaling Solution:
  • 5. Start the Pump:
  • 6. Flush the Heat Exchanger:
  • 7. Final Steps:
• How To Clean A Tankless Water Heater Filter?
• How Often To Descale A Tankless Water Heater? 
• How Much Does It Cost To Descale A Tankless Water Heater? 
  • DIY Descaling Cost
  • Professional Descaling Cost
  • Frequency of Descaling
• FAQs
• Conclusion

What Are TheTools & Equipment You Need To Descale A Tankless Water Heater?

To descale a tankless water heater, you will need the following tools and equipment:

• Five-gallon bucket
• Three to four gallons of distilled, food-grade white vinegar (or an approved descaling solution)
• Two ¾ inch connection drain hoses
• Submersible pump
• Safety equipment (rubber gloves, face mask, eye protection)

The key items are:

• Descaling solution: You can use a commercial descaling product or a DIY solution like distilled white vinegar.

• Hoses: You’ll need two drain hoses, often double-ended washing machine hoses, to connect the pump and circulate the descaling solution.

• Submersible pump: This pump will circulate the descaling solution through the tankless water heater.

• Five-gallon bucket: To hold the descaling solution and collect the drained water.

.Some descaling chemical companies sell these components as a kit, but you can also purchase the individual items separately.

I recommend you check out this article if you want to buy tankless water heater flush kits, instead of purchasing items separately. 

How To Descale A Tankless Water Heater?

Here are the seven easy-to-follow procedures to descale a tankless water heater like a pro

1. Preparation:

• Turn Off Gas: Switch off the gas supply to the unit but keep the power on.

• Shut Off Water Supply: Close both the hot (red) and cold (blue) water valves.

2. Drain Excess Water:

• Remove Drain Caps: Take off the drain caps on both the hot and cold valves.

• Drain Water: Place a bucket under the hot water side and open the red drain valve to let any excess water drain out. Repeat this for the cold water side.

3. Set Up the Pump:

• Connect the Pump: Attach one hose to the submersible pump and place the pump in the bucket.

• Attach Hoses: Connect the pump outlet hose to the cold water drain valve and a second drain hose to the hot water drain valve, placing the other end in the bucket.

4. Add Descaling Solution:

• Pour Vinegar: Fill the bucket with 3-4 gallons of vinegar, ensuring the pump is submerged.

5. Start the Pump:

• Open Drain Valves: Open both drain valve handles.

• Turn On the Pump: Activate the pump to circulate the descaling solution through the heater. Let it run for at least 30 minutes to an hour. For best results, consider changing the vinegar solution after 30 minutes.

6. Flush the Heat Exchanger:

• Turn Off Pump: After the descaling period, turn off the pump and close the cold water drain valve.

• Remove Hoses: Disconnect the hose from the cold water drain valve and replace the cap.

• Flush with Fresh Water: Place the hot water drain hose back into the bucket and open the cold water main valve to flush the heater with fresh water for at least five minutes.

7. Final Steps:

• Drain Residual Solution: For condensing units, open the drain cock to remove any leftover descaling solution.

• Clean Water Filter: If applicable, unscrew and clean the water filter under running water, then replace it.

• Reassemble: Close the drain valve, remove the drain hose, and secure the drain cap tightly.

• Restore Gas and Power: Turn the hot and cold valves back to the “ON” position and restore the gas supply. Reset the unit by turning it off and then back on to clear any error codes.

How To Clean A Tankless Water Heater Filter?

Here are the steps to clean the water filter on a tankless water heater:

1. Turn off the gas and power to the unit.

2. Shut off the water supply to the heater by turning the hot and cold water valves to the closed position.

3. Remove the drain caps on the hot and cold water valves.

4. Place a bucket under the hot water drain valve and open it to drain any excess water. Repeat for the cold water side.

5. Locate the water filter, usually found near the water inlet. It may be secured with a single screw.

6. Remove the filter by unscrewing the screw, pulling it slightly towards you, and sliding it to the left to angle it over the motor.

7. Take the filter to an outdoor water spigot and rinse it thoroughly with a strong water stream to remove any debris.

8. Dry the filter as best as possible using paper towels.

9. Reinstall the clean filter by reversing the removal process.

10. Close the drain valves, turn the water supply back on, and check for any leaks.

11. Restore power and gas to the unit.

How Often To Descale A Tankless Water Heater?

Flush your tankless water heater one or two times a year, depending on the hardness of the water.

Here’s a summary of the recommended descaling schedule:

Descaling Frequency

• Once a Year: For areas with soft water. This interval helps prevent scale buildup and maintains the efficiency of your tankless water heater.

• Every 6 Months: If you live in a moderate water hardness area, flush your tankless water heater every six months.

• Every 3 Months: Hard water contains high levels of minerals like calcium and magnesium, which can lead to significant scale buildup. More frequent descaling (flushing the tankless unit every three months) is necessary to ensure optimal performance and longevity of the heater.

Additional Considerations

• Always check the user manual for recommendations for your specific model, as some may have different guidelines or provide descaling kits.

• Regular descaling prevents scale buildup. It also helps maintain the efficiency of the heating elements. This ensures a consistent hot water supply and extends the lifespan of the tankless water heater.

By adhering to these guidelines, you can ensure your tankless water heater operates efficiently and reliably.

How Much Does It Cost To Descale A Tankless Water Heater?

The cost of flushing a tankless water heater is typically between $105 and $180. However, the cost to descale a tankless water heater can vary, depending on whether you do it yourself or hire a professional plumber.

Here’s a breakdown of the costs:

DIY Descaling Cost

If you do it yourself, the total cost for the necessary equipment and materials is around $100-$120 for the first time, and only $30 for subsequent descalings. The required items include:

• Submersible pump ($30-$50)
• Hoses ($10-$20)
• Descaling solution (3-4 gallons of white vinegar or a commercial product like J.C. Whitlam Flow-Aide or Urnex Dezcal, costing $20-$70)
• Bucket (already owned)

Professional Descaling Cost

If you hire a professional plumber, the cost to descale a tankless water heater ranges from $180 to $350 per flush. Some key factors that affect the cost include:

• Labor rates of the plumber
• Complexity of the unit
• Accessibility of the heater
• Additional services included (e.g. filter cleaning)

Frequency of Descaling

Manufacturers recommend descaling tankless water heaters at least once a year, or every 6-9 months if you have hard water. 

Regular descaling helps maintain efficiency and prevent mineral buildup that can damage components like the heat exchanger over time. 

In summary, while hiring a professional is more convenient, descaling a tankless water heater yourself can save you $50-$320 per flush. With the right tools and a little time, it’s a cost-effective way to keep your tankless heater running smoothly.

FAQs

What are the signs that my tankless water heater needs descaling?

Here are the key signs that indicate your tankless water heater needs descaling:

• Reduced hot water flow
• The unit makes unusual noises or vibrations
• Fluctuating water temperatures
• Increased energy consumption

If you notice any of the signs mentioned above, take prompt action and descale your tankless water he

How long does it typically take to descale a tankless water heater?

Descaling a tankless water heater takes 1 to 2 hours in total. It includes the time needed for setup, running & circulating the descaling solution, and flushing the heat exchanger afterward.

Are there any safety precautions I should take when descaling a tankless water heater?

Yes, you should follow and maintain some safety precautions like turning off the power, ensuring proper ventilation, and wearing protective goggles and gloves are essential when descaling a tankless water heater. 

Conclusion

Regular maintenance and descaling of your tankless water heater has numerous advantages, including:

• It prevents scale buildup
• Improve energy efficiency
• Ensure consistent hot water supply
• Prolong the lifespan of your tankless water heater
• Reduce the risk of costly repairs

Fortunately, I described how to descale a tankless water heater like a pro. Follow the instructions and flush your tankless water heater without hiring a professional.