Stiebel Eltron Flow Sensor Troubleshooting

You will get no hot water from your Stiebel Eltron tankless unit if its flow sensor is defective. And this guide on Stiebel Eltron Flow Sensor Troubleshooting will disclose everything behind this issue. 

Turns out, I will walk you through a step-by-step procedure to replace the flow sensor like a pro. 

As a result, you can’t only replace the flow sensor by yourself but also enjoy the warmth of hot water on the ice-cold days of winter. On top of this, it will save you money as you don’t need to hire a professional. 

So, let’s get started. 

Table of Contents

• Stiebel Eltron Flow Sensor Troubleshooting [The Ultimate Guide]
  • 1. Flow Sensor Gets Clogged 
  • 2. O-ring Gets Damaged 
  • 3. Broken Flow Sensor
• How To Replace Flow Sensor On Stiebel Eltron Tankless Water Heater?
• How Do I Reset My Stiebel Eltron
• End-Note

Stiebel Eltron Flow Sensor Troubleshooting [The Ultimate Guide]

Here, I will explain three common problems of the flow sensor and provide their solutions as well.

1. Flow Sensor Gets Clogged

Over time, the flow sensor of the unit gets restricted by scale or lime buildup. When the flow sensor becomes clogged, it doesn’t sense the presence of water flow. 

In other words, the scale or debris buildup in the flow sensor hinders the workflow of the sensor. As a result, it doesn’t sense the water flow and prevents the unit from heating. 

How To Fix: 

Freeing the build up from the flow sensor might fix this issue. In order to do this, follow the below step-by-step procedure: 

To begin with, turn the water going to the unit off. Also, shut the power off to it at the circuit breaker.

Then, take the electrical piece or the wire connector off from here at the top: 

Also, lift up this little pin from the top of the flow sensor using a flat blade screwdriver: 

Now, loosen up the nut from the bottom part of the flow sensor that keeps that sensor in place. 

After that, wiggle up the flow sensor and remove it from its place. 

It’s time to blow away the dirt buildup from the flame sensor. Just get an air compressor and blow the buildup away. 

Finally, rinse the flame sensor. 

2. O-ring Gets Damaged

The O-ring between the flow sensor and the nut can also wear out over time, which can cause the flow sensor to malfunction. 

To fix this issue, what you need to do is just remove the flow sensor from its place and inspect the O-ring. 

If it gets damaged, replace it with a new one. 

3. Broken Flow Sensor

If cleaning the flow sensor or replacing its O-ring don’t bring any luck, I bet the flow sensor is at fault. 

In this case, you don’t have any option- except replacing the flow sensor. And the next chapter will take you through the step-by-step procedure to replace the flow sensor. 

How To Replace Flow Sensor On Stiebel Eltron Tankless Water Heater?

Replacing the flow sensor on Stiebel Eltron is not rocket science. To get the flow sensor replaced, go along with the following steps: 

1. Turn the water supply to the water heater off by moving the cold water supply valve counterclockwise. 

2. Shut the electric supply off to the unit at the circuit breaker. 

3. Drain the water heater by turning the hot water faucet.

4. Open the access panel to get the flow sensor. And this is how the flow sensor looks like: 

5. Disconnect the wire connector from here at the top: 

6. Use a screwdriver to lift up the tiny pin from the top of the flow sensor. 

7. Unscrew the nut that holds the flow sensor in place by using an adjustable wrench. 

8. Raise up this whole thing while the flow sensor will also raise up at the same time. 

9. Wiggle the flow sensor and take it out from its place. 

10. Install the new flow sensor by wiggling it a bit. Don’t forget to put on an O-ring that goes on the underneath part of the sensor. Then, tighten up the nut to secure the flow sensor.

How Do I Reset My Stiebel Eltron

If you get lukewarm water out of the unit, a tripped thermal safety cut-out switch is the possible reason behind this issue. 

In this case, resetting that switch or button will help you resolve the problem. 

Here below, I will describe the step-by-step procedure to reset the Stiebel Eltron Tankless Water Heater correctly. 

1. Turn off and lock out all the circuit breakers to the water heater. 

2. Take the screw out on the right side of the unit to open the face of your water heater.

3. Locate the thermal safety reset buttons. You can find these buttons on the top of each copper heating vessel. 

4. Now, take a pencil with eraser (if you don’t have an insulated tool) and press those two reset buttons. If the button clicks when depressed, understand the unit has been reset. 

5. Close the front cover and reinsert the screw on the right side. 

6. Remove the circuit breaker locks and turn on all the circuit breakers connected to the water heater.

End-Note

Defective flow sensor on Stiebel Eltron or other tankless water heaters means you will get no hot water out of the unit. 

Either you need to clean the flow sensor or replace it if you want to get hot water out of your Stiebel Eltron. 

Luckily, I described how to clean or replace the flow sensor to resolve this issue. So, follow the guidelines I mentioned and fix the problem.