Descaling a tankless water heater is a crucial maintenance task that helps ensure its efficient operation and longevity. Over time, mineral deposits, particularly calcium and magnesium, can accumulate inside the heat exchanger of a tankless water heater, hindering heat transfer and reducing its overall performance. Descaling involves removing these deposits to restore the heater’s efficiency and maintain a steady flow of hot water. Here’s a guide on how to descale a tankless water heater.

  1. Turn Off Power and Gas Supply: Before starting any maintenance on your tankless water heater, it’s essential to turn off the power and gas supply. This ensures safety during the descaling process. For electric units, locate the circuit breaker connected to the water heater and switch it off. For gas units, turn off the gas supply valve.
  2. Gather Supplies: You’ll need some essential supplies for descaling, including a bucket, a submersible pump (or a compatible descaling pump kit), white vinegar or a descaling solution, hoses, and a wrench. Check your water heater’s manual for specific recommendations on descaling solutions.
  3. Connect Hoses and Pump: Connect one end of a hose to the cold water valve on the water heater and the other end to the pump’s inlet. Connect a second hose from the pump’s outlet to the hot water valve on the water heater. Ensure that the hoses are securely attached to prevent leaks.
  4. Add Descaling Solution: If you’re using a commercial descaling solution, follow the manufacturer’s instructions for dilution. If you’re using white vinegar, you can use it undiluted. Pour the descaling solution into a bucket and place the submersible pump into the bucket.
  5. Circulate the Descaling Solution: Start the pump to circulate the descaling solution through the water heater. Allow the solution to flow through the system for at least 45-60 minutes. This time frame ensures that the solution has sufficient contact with the mineral deposits inside the heat exchanger.
  6. Flush the System: After the descaling solution has circulated, turn off the pump and disconnect the hoses. Open both the hot water and cold water valves on the water heater to flush out any remaining descaling solution. Connect a hose to the cold water valve and place the other end in a drain or bucket. Open the cold water valve to flush the system thoroughly.
  7. Check for Residue: Inspect the water that comes out during the flushing process. If you notice any residue or sediment, repeat the descaling process until the water runs clear. This ensures that all mineral deposits are effectively removed.
  8. Reconnect and Restore: Once the flushing is complete, reconnect the water heater to the power and gas supply. Turn on the water heater and let it run for a few minutes to ensure proper functioning. Check for any leaks around the connections.
  9. Regular Maintenance: To prevent excessive buildup of mineral deposits in the future, consider installing a water softener or a whole-house water filter. Regularly descale your tankless water heater based on the manufacturer’s recommendations or at least once a year, depending on the water hardness in your area.
  10. Consult the Manual: Always refer to your specific water heater’s manual for manufacturer recommendations and any specific descaling instructions or precautions. Following the manufacturer’s guidelines helps maintain your warranty and ensures safe and effective descaling.

Regular descaling of your tankless water heater is a simple yet essential task that can significantly extend its lifespan and maintain its efficiency. Taking the time to perform this maintenance routine ensures a reliable supply of hot water for your household.