Step-by-Step Guide to Installing Your Flow Sensor

Servicing your electric tankless water heater doesn’t have to be intimidating. With this detailed guide tailored for 18-36 KW models, you’ll learn how to replace the flow sensor, clear debris from the screen and impeller, and replace the flow meter impeller—keeping your heater running efficiently for years. Let’s dive into these essential maintenance tasks with clear instructions and helpful visuals.

Tools You’ll Need for Tankless Water Heater Maintenance

Before you begin, gather these tools to make the process smooth and safe:

• Phillips-head screwdriver
• Wire cutters
• Needle nose pliers
• Rag or paper towel (for cleaning)

How to Safely Decommission Your Tankless Water Heater

Safety comes first! Decommissioning your heater is a critical step before any maintenance. Here’s how to do it properly:

1. Disconnect power from the heater by turning off the circuit breaker.
2. Close the inlet water pipe valve to stop water flow.
3. Disconnect the outlet of the heater and let the water drain into a bucket.

Replacing the Flow Sensor in Your Tankless Water Heater

The flow sensor monitors water flow, ensuring your heater operates correctly. A faulty sensor can lead to performance issues. Follow these steps to replace it (Note: The document mentions "temperature sensor," but the steps describe the "flow sensor," so we’ve corrected this for accuracy):

1. Remove the cover from the heater by unscrewing the 2 screws on the top and bottom.

       2.Locate the flow sensor and its connection to the control board.

Removing & Replacing the Flow Sensor

1. Use a Phillips-head screwdriver to remove the flow sensor from the flow meter housing.
2. Disconnect the flow sensor from the board.
3. Use wire cutters to remove any zip ties securing the flow sensor wire.
4. Replace the old flow sensor with a new one, plugging it into the board.
5. Use a Phillips-head screwdriver to secure the new flow sensor to the flow meter housing.
6. Reattach any zip ties you removed earlier.
7. Recheck all electrical connections before recommissioning the heater.
8. Purge air from the system before turning the unit back on to avoid damage.

Clearing Debris from the Screen and Impeller

Debris buildup can clog the screen and impeller, reducing water flow and efficiency. Regular cleaning keeps your heater in top shape. Here’s how:

1. Remove any hoses or connections from the inlet fitting of the heater.
2. Use needle nose pliers to remove the inlet screen by grabbing the rubber edge.

: Extracting the inlet screen with needle nose pliers.

1. Clean the screen under running water with a rag or paper towel, then set it aside.
2. Use needle nose pliers to remove the retaining wire from the inlet fitting.
3. Use needle nose pliers to remove the flow meter turbine from the inlet fitting. (Note its orientation for reinstallation.)

: Removing the turbine with needle nose pliers.

1. Gently pull apart the flow meter turbine and clean it with water and a rag. (Be careful not to lose the small propeller inside.)
2. Reassemble by inserting components back into the inlet in this order: turbine (in its original orientation), retaining wire, inlet screen.
3. Recheck all electrical connections before recommissioning the heater.
4. Purge air from the system before turning the unit on.

Replacing the Flow Meter Impeller in Your Tankless Water Heater

A damaged impeller can disrupt water flow measurement, affecting heater performance. Replace it with these steps:

1. Remove any hoses or connections from the inlet fitting of the heater.
2. Use needle nose pliers to remove the inlet screen by grabbing the rubber edge.
3. Use needle nose pliers to remove the retaining wire through the inlet fitting.
4. Use needle nose pliers to remove the flow meter turbine through the inlet fitting. (Note its orientation for reinstallation.)

 Extracting the turbine to access the impeller.

1. Remove the damaged impeller and replace it with a new one. Reassemble by inserting components back in this order: turbine, retaining wire, inlet screen.
2. Recheck all electrical connections before recommissioning the heater.
3. Purge air from the system before turning the unit on.

Keep Your Tankless Water Heater Running Smoothly

By following this guide, you’ve mastered the key maintenance tasks for your 18-36 KW electric tankless water heater. Regular upkeep, like flow sensor replacement and debris clearing, ensures efficiency and longevity. Always prioritize safety—double-check connections and consult a professional if needed. Enjoy the benefits of a well-maintained heater!