Flushing a Tankless Water Heater to Remove Hard Water Scale

Stiebel Eltron Flow-Aide Water Heater De-Scaling Kit (#540000)

If you have hard water and are using a water heater you have two options when it comes to mineral scale. You can either prevent it from building up with an ecoTAC Protector Tankless Water Heater Filter, or follow the instructions below for flushing your tankless water heater. Aside from the benefit of requiring less work, using an ecoTAC filter to prevent mineral scale also ensures optimal performance of your heating elements / heat exchanger. Our ecoTAC filters reduce the risk of pre-mature equipment failure and maintain optimal flow performance.

Required Equipment

How to Flush / Descale a Tankless Water Heater

These instructions assume you have the Isolation Valve Kit Installed

  1. Disconnect the power to your tankless water heater.
  2. Close the hot and cold isolation and service valves and remove service caps.
  3. Pour approximately 1.5 gallons of water into the bucket and place it under water heater.
  4. Add contents of 1 quart bottle of Flow-aide into the bucket (bucket should be filled approximately half full).
  5. Connect the hose to the pump, and other end of the hose to the cold service valve. Place the pump into the bucket.
  6. Connect the second hose to hot service valve. Place other end in bucket. (effectively creating a loop from the bucket through the tankless water heater
  7. Open both hot and cold service valves.
  8. Plug the pump into grounded receptacle.
  9. Allow the pump to circulate Flow-aide solution through heater for 30-45 minutes. Unplug pump to stop it.
  10. Close cold service valve. Remove the hose from cold service valve, and replace service cap.
  11. Disconnect the hose from the pump and remove pump from bucket. Discard Flow-aide solution.
  12. Flush your tankless water heater for 3-5 minutes or until water flows clear by opening the cold isolation valve and allowing water to exit through the hot service valve into a drain or bucket. If using a bucket, empty as necessary.
  13. Close hot service valve. Remove hose from service valve and replace service cap.
  14. Open hot isolation valve.
  15. Connect power to water heater and return appliance to service.

If you have any questions please call our tankless experts toll free at 1-877-374-2696 and they would be happy to help.