Stiebel Eltron Tankless Water Heater Troubleshooting [A Complete Guide]

Experiencing issues with your Stiebel Eltron tankless water heater now and then is common and very annoying. Even more annoying is not knowing what’s going on with the heater and how to resolve it.

So, how to perform Stiebel Eltron tankless water heater troubleshooting?

To troubleshoot the problems of Stiebel Eltron tankless water first you have to identify the problem. There can be several problems including – 

  • No power in the water heater
  • The water not getting enough hot
  • Getting fluctuating water temperature from the heater
  • Unusual noises coming up from the heater, and so on. 

However, if you are looking for model-specific problems, you may find some dissimilarities. For example, the Tempra Plus and DHC models can sometimes have different reasons for not heating enough. 

Aside from these, there are more problems which you have to identify. All problems come with different reasons and solutions. To know them all, keep reading…  

stiebel eltron tankless water heater troubleshooting

Stiebel Eltron Tankless Water Heater Troubleshooting

Here are the details of all major Stiebel Eltron tankless water heater problems, explained with the corresponding reasons and effective solutions. Let’s start-

01. Stiebel Eltron Tankless Water Heater No Power

If you are not getting power to your water heater, there can be several reasons behind it. Let’s see them at a glance before going to the discussion. 

Reasons Solutions 
Tripped or Blown FuseReset or replace the fuse
Low Water Flow RateIncrease the water flow rate 

Reason 1: Tripped or Blown Fuse

When a Stiebel Eltron Tankless Water Heater has no power, the most possible reason is a tripped fuse. If the heater draws too much current or there is a short circuit, the fuse can trip and cut off the power supply.

In this case, you will hear an audible click while turning on the heater, but the heater won’t get any power. 

How to Fix It:

Locate the electrical panel in your home and look for the fuse for your Stiebel Eltron water heater. The fuse should be a 40 amp one. 

If the fuse is tripped, turn it back to the “On” position. Also, check if the fuse is blown. Visibly look for cracks or burns. If the fuse is blown, you have to replace it with another 40 amp fuse.

Reason 2: Low Water Flow Rate

If the fuse is in good condition, another reason for a Stiebel Eltron Tankless Water Heater having no power is a low water flow rate. 

Stiebel Eltron tankless water heaters require a minimum flow rate per minute to activate the heating element and start providing hot water. If the flow rate falls below the required threshold (usually around 0.5 to 3 liters per minute depending on the heater size), the heater may not turn on.

How to Fix It:

Check if other faucets in your home have a similar problem with low water flow. You can use a jug with measuring points to measure the water flow. And then match the flow rate with the recommended rate for your heater. The minimum flow rate is given in Stiebel Eltron’s owner’s manual. 

If other faucets also have low flow, the issue is with the overall water supply system. And in this case, you need to call your local plumber to fix the supply problem. 

However, if the other faucets have a higher flow rate, the issue is specific to the tankless water heater. In this case, increase the flow rate by turning the flow adjustment screw clockwise slightly. You will find this screw on the cold water inlet. Make sure not to loosen the screw too much. Otherwise, there will be excessive flow. 

If the water flow is too low, you won’t hear any audible click from the unit even if you start the heater. So, after taking these corrective measures, if you hear an audible click after turning on the heater, you will know the water flow is accurate now. 

02. Stiebel Eltron Tankless Water Heater Not Getting Very Hot 

It is very annoying when the heater is working fine but you are not getting enough hot water. Here are the reasons why this problem is happening. 

Reasons Solutions 
Activated internal anti-scalding protection systemNo need to take corrective measure
Water Flow Too HighDecrease the water flow rate 
Voltage Too LowIncrease the voltage as per the demand

Reason 1: Activated Internal Anti-Scalding Protection System

The anti-scalding is a safety feature that helps to prevent scalding. If this safety feature is activated, you won’t be able to set the high level of water temperature. And the water will not be too hot. 

How to Fix It:

It is possible to adjust the anti-scalding feature to a higher temperature level. But it is usually not recommended. 

And if you really need to do it, I advise against attempting to adjust the internal anti-scalding protection system on your own. It’s best to have a certified technician handle this task for you.

Reason 2: Water Flow Too High

If your Stiebel Eltron Tankless Water Heater is not getting very hot, one possible reason is that the water flow rate is too high. 

Stiebel Eltron tankless water heaters require a specific flow rate to heat the water effectively. If the flow rate exceeds the heater’s capacity, the water will not have enough time to heat up properly. This will result in lower temperatures.

How to Fix It:

Check the owner’s manual of your Stieble Eltron heater and find the maximum flow rate. If the flow rate seems excessive, adjust it by turning the flow adjustment screw counterclockwise. Make sure not to turn too much. 

Reason 3: Voltage Too Low

Another reason why your Stiebel Eltron Tankless Water Heater may not be getting very hot is if the voltage supplied to the heater is too low.

How to Fix It:

All the models of Stiebel Eltron tankless water heaters require different voltage levels to operate. Get the specific voltage for your heater from the owner’s manual. And then make sure to provide that much voltage. 

However, if you are facing an issue where when hot water is being used, there is a brief period where cold water initially flows, you don’t have to worry. 

In Stiebel Eltron tankless water heaters, especially in Stiebel DCE Premium models, water requires a few moments to get hot. During that brief period, you will get cold water. You don’t have to take any corrective action, all you have to do is wait patiently. 

03. Stiebel Eltron Tankless Water Heater Fluctuating Water Temperature

The fluctuating water temperature can be risky if suddenly there is a risk of extremely hot water. So, this problem should be immediately fixed. 

This problem is very common, especially in Stiebel Eltron Tempra 24 plus. So, while you do any Stiebel Eltron Tempra 24 plus troubleshooting, this segment will come in handy. 

The common reasons behind this fluctuating problem are given below. 

Reasons Solutions 
Unstable Supply Water TemperatureInstall a thermostatic mixing valve in your heater
Inconsistent Flow RateClean mineral build-ups from the aerators
Malfunctioning Flow SensorRepair or replace the flow sensor 

Reason 1: Unstable Supply Water Temperature

Sometimes, due to the weather of your region, the supply water temperature can fluctuate. The fluctuating water coming through the cold water inlet of the heater can cause the heater to heat water at an inconsistent temperature.

How to Fix It:

If the supply water in your region has a fluctuating temperature, you can install a thermostatic mixing valve in your heater. This will help stabilize the incoming water temperature and will provide a stable water temperature. 

Here’s how to install the thermostatic mixing valve in your heater. 

Step 1: First, turn off the power supply and water supply to the water heater. Drain the hot water by opening a faucet in your home. Wait at least half an hour to let the heater cool down before you work on it.

Step 2: Remove the cap and elbow from the inlet side of the water heater.

Step 3: Now you have to set up the mixing valve. First, install the new valve by inserting it into the opening. Make sure that it sits securely on the lip. Use rubber washers on both sides of the valve for proper sealing.

use rubber washers for the mixing valve of steibel eltron water heater

Step 4: Now, apply pipe joint compound or Teflon tape to the threads of the valve’s connections. Attach the valve connections on both sides using the provided plugs.

Step 5: After that, secure the valve by tightening the connections with a wrench. Make sure that the pipes are fully inserted into the valve before tightening.

Step 6: Use an olive to connect the pipe from the water supply to the valve. Slide the olive onto the pipe and insert it into the valve. Make sure there is a tight fit.

use an olive to connect the pipe

Step 7: Now, apply pipe joint compound or paste on the inside rim of the fitting before screwing it onto the valve.

Step 8: Check the correct orientation of the valve, ensuring that the hot water enters the hot side and the cold water enters the cold side of the valve. And, if necessary, adjust the preset temperature of the thermostatic mixing valve. 

The installation process is done. 

Reason 2: Inconsistent Flow Rate

Another reason for the fluctuating water temperature in your tankless water heater is an inconsistent flow rate. If the water flow rate is not consistent, it can affect the heater’s ability to heat the water at a constant temperature.

How to Fix It:

Check the aerators on the water supply and see if it is clogged with mineral build-up. Remove the cap and elbow from the inlet side of the water heater. And then use compressed air to remove the debris from the water source. 

Reason 3: Malfunctioning Flow Sensor

The flow sensor in your Steibel Eltron water heater detects the water flow rate and signals the heater to adjust the heating power accordingly.

If the flow sensor is not functioning properly, it will not accurately measure the flow rate. This will lead to the water temperature fluctuating.

How to Fix It:

You have to troubleshoot the flow sensor and repair or replace it accordingly. 

To troubleshoot the Stieble Eltron flow sensor, first, you need to identify the symptoms to know if you need troubleshooting. After that, you have to go for these troubleshooting steps. 

  1. Check if the flow sensor is clogged
  2. Check if the O-ring to the flow sensor is damaged
  3. Check if the flow sensor itself is broken. 

To know the symptoms of a malfunctioning flow sensor and the troubleshooting steps in detail, read this guide on Stiebel Eltron Flow Sensor troubleshooting.

04. Stiebel Eltron Tankless Water Heater Red Light On The Heater

If you notice the red light is On in your Stiebel Eltron tankless water heater, then you have to check and address two issues. Let’s discuss those.

Reasons Solutions 
Faulty Heating ElementReplace the heating element 
Faulty Temperature SensorReplace the temperature sensor

Reason 1: Faulty Heating Element

The heating element is responsible for heating the water as it flows through the heater. When the heater detects a faulty heating element, it illuminates the red light to indicate the problem.

How to Fix It:

Here’s how to test and replace the heating element in the Stiebel Eltron water heater. 

Step 1: Before starting the testing and replacing process, make sure that the power supply to the water heater is turned off. And let the heater cool down for a bit. 

Step 2: Locate the heating elements in your Stiebel Eltron Tankless Water Heater. The number and location of the elements vary depending on the model of your water heater. You have to remove a cover or access panel to reach them. Unscrew the bolts of the cover and remove the cover. 

stiebel eltron tankless water heater heating element

Step 3: Once you have reached the heating elements, you have to test them one by one with an ohm meter.

Step 4: Touch the meter’s probes to the terminals of the heating element. If the meter shows continuity (beeping sound), the element is functioning properly. If there is no continuity (no sound), it indicates a bad heating element. The bad elements need to be replaced. 

test the stiebel eltron tankless water heater heating element with ohm meter

Step 5: With a star-headed screwdriver, remove the nuts securing the wirings to the faulty element. 

Step 6: Use an element wrench to take out the element from the heater. 

Step 7: Place the new element on the housing and use the element wrench to tighten the element back in place. 

Step 8: Connect the wiring and replace the cover.

You can follow this video for a more detailed explanation of the whole process of tankless water heater heating element replacement.

Reason 2: Faulty Temperature Sensor

If the heating element is working fine, another reason for the red light on the heater is a faulty temperature sensor. It can be either the inlet temperature sensor or the outer one. 

How to Fix It:

You need to replace the temperature sensor in your water heater. This is a complicated process and should be done by a certified dealer. The compatibility matching of the sensor with the specific brand is also important.

05. Stiebel Eltron Tankless Water Heater Leaking

You may sometimes notice water around the tankless water heater. You should immediately take action as it can further damage the heater. Here are the reasons behind this water leak.

Reasons Solutions 
Loose Flow Adjustment ScrewTighten the flow adjustment screw
Damaged Seals Or GasketsReplace the seals or gaskets
Internal Component FailureConsult a qualified technician 

Reason 1: Loose Flow Adjustment Screw

If you notice that your Stiebel Eltron electric tankless water heater is leaking from the flow adjustment screw, it is due to a loose or damaged screw.

While you are doing Tempra tankless water heater troubleshooting, focus on this problem more, as many users of this model complain about it. 

How to Fix It:

Here’s how to fix the leaking from the flow adjustment screw. 

Step 1: First of all, switch off the power supply to the water heater. 

Step 2: Now you have to locate the flow adjustment screw. The screw in the Stiebel Eltron tankless water heater is usually located near the inlet or outlet pipes of the water heater.

Step 3: Visually inspect the screen for any corrosion or damage. If it is corroded or damaged, replace the screw with a new one. 

Step 4: Use a screwdriver to gently tighten the flow adjustment screw. Be cautious not to over-tighten it, as this may cause additional damage.

Step 5: Turn the power back on to the water heater and observe for leakages. 

Reason 2: Damaged Seals Or Gaskets

Another reason for a leaking Stiebel Eltron Tankless Water Heater could be damaged seals or gaskets. 

Carefully inspect all fittings, connections, and areas around the water heater to determine the exact location from where the water is leaking. It could be around pipes, valves, or other components. 

How to Fix It:

Now that you have found the leaking components, here’s what you have to do. 

  1. Turn off the power supply to the heater.
  2. Disassemble the leaking fittings or connections to access them.
  3. Carefully remove the damaged seals or gaskets using an adjustable tool including a wrench or screwdriver. Be gentle to avoid causing further damage to surrounding components.
  4. Install the new seals or gaskets in the same location where the old ones were removed. 
  5. Once the new seals or gaskets are in place, reassemble the fittings or connections. Make sure that all connections are tightened securely but avoid over-tightening.

Reason 3: Internal Component Failure

Internal component failure can also result in a water leak in a Stiebel Eltron Tankless Water Heater. 

Various internal components, including valves, pressure relief valves, or heat exchangers, can experience wear and tear over time. If any of these components fail or malfunction, it can cause water to leak from the heater.

How to Fix It:

In the case of internal component failure, it is best to contact the manufacturer’s customer support or a qualified technician. They can efficiently diagnose and repair the specific component causing the leak without doing further damage to the heater. 

06. Stiebel Eltron Tankless Water Heater Unusual Noises

If you often hear unusual noises from your tankless water heater, the following reasons can be the culprit behind it. Whether you are doing a Tempra Plus water heater troubleshooting or any other tankless model, these reasons are common. 

Reasons Solutions 
Scale BuildupDescale the heater
Damaged Or Loose ComponentsTighten or replace components 
Fluctuating Water PressureInstall a water hammer arrestor 
The Heater Is Not Vented ProperlyProperly vent the heater

Reason 1: Scale Buildup

One reason for unusual noises in a Stiebel Eltron Tankless Water Heater is scale buildup. Scale refers to mineral deposits that accumulate over time on the internal components of the water heater. 

As the water passes through the heater, these minerals can settle and harden on the heating elements or other surfaces and cause unusual noises from the heater. 

How to Fix It:

The manufacturers of the Stiebel Eltron water heater recommend descaling the heater every six months. So, if you haven’t done descaling in the last six months, do it immediately. 

Here’s how to descale Stiebel Eltron tankless water heater with vinegar solution. 

Step 1: First, turn the hot water and cold water valves connected to the water heater.

Step 2: Then, open the drain valve on the heater and drain any remaining water from the unit.

Step 3: Connect two hoses to the inlet and outlet ports of the water heater. Place the other ends of the hoses into a bucket containing a solution of white vinegar.

Step 4: Start a pump or initiate water flow to circulate the vinegar solution through the water heater. The vinegar helps dissolve and remove mineral deposits or scales that have accumulated inside the unit.

Step 5: Allow the vinegar solution to circulate through the water heater for approximately one to one and a half hours. This time frame may vary depending on the severity of the scale buildup. For example, if you have descaled before 6 months, the buildup will be lesser. 

descaling the stiebel eltron tankless water heater

Step 6: After the desired time has passed, disconnect the hoses from the water heater. Close the drain valve and remove the hoses used for draining. 

Step 7: Turn on the cold water valve and let water flow through the heater to flush out any remaining vinegar and loosened scale. Continue flushing until the water runs clear.

Step 8: Once the water runs clear, reconnect the hot water and cold water valves to restore the water supply to the heater.

Reason 2: Damaged Or Loose Components

Another reason for unusual noises is damaged or loose components within the water heater. 

Over time, components including valves, pipes, or fittings can wear out or become loose. As water flows through the system, these damaged or loose components vibrate, rattle, or produce other unusual sounds.

How to Fix It:

Inspect the water heater for any damaged or loose components. Tighten or replace any loose or faulty parts as needed. If you can’t figure out which part is loose, consult a professional technician for help.

Reason 3: Fluctuating Water Pressure

Fluctuating water pressure can also contribute to unusual noises in a tankless water heater. If the water pressure in the plumbing system is not stable, it can cause vibrations or water hammering. 

How to Fix It:

You can install a water hammer arrestor in the inlet part of your water heater. This will help stabilize the water flow and cancel out the noise. 

Reason 4: The Heater Is Not Vented Properly

If you are getting a boiling noise from the heater, that means the heater isn’t vented properly. 

How to Fix it:

To prevent boiling noises in the water heater, make sure it is vented properly.

When starting the water heater for the first time, remember to activate the AE3 safety switch before supplying power to the unit. Otherwise, it won’t turn on until the safety switch is engaged.

During the initial start-up, open and close all connected draw-off valves for at least 15 minutes. This will help in the proper functioning of the water heater. Also, let the water run for about 3 minutes to remove any air from the pipes and the water heater.

Check the supply pressure and ensure it is at least 26.1 PSI for the water heater to work. But don’t let it exceed 145 PSI to avoid any potential issues.

07. Stiebel Eltron Water Heater Not Turning On

If your Steibel Eltron water heater is not turning on, there can be several reasons behind it. 

Those reasons are, 

  1. Lack of power in the unit. If this is the reason, even though the DHW (Domestic Hot Water) valve is fully open, the unit will not start.
  2. Improper wiring connections
  3. The safety thermal cut-off is tripped or closed
  4. The thermostat is broken or old

How to Fix it:

If there is okay from the power connection to your unit but the Stiebel Eltron water heater won’t turn on, be sure there are any faulty wiring connections in the system. In this instance, inspect your entire water heater and recognize the faulty connection. Fix those. 

Then head over to the safety thermal cut-off to see whether it gets tripped or closed. If so, simply open it by pressing the red reset button on the thermal cut-out. Next, inspect the thermostat as well as the possibility that the element is broken and leads to turning off your unit. Test the terminals of the thermostat for continuity and replace if faulty. 

Lastly, check whether you’re experiencing system overload in your unit. Too much load in the system shuts off the heater immediately. In this instance, turn off a few of the hot water fixtures and see if your heater is back to normal operation. 

08. Stiebel Eltron Water Heater Keeps Tripping

There are several reasons behind this annoying tripping problem of the Stiebel Eltron Water Heater. Here are the reasons-

  1. Obstruction or blockage in the heat exchanger
  2. Damage or burning of the heating element
  3. Inaccurate or dysfunctional flow sensor
  4. Degradation or wear of the heating element
  5. Faulty operation of the thermostat
  6. Dysfunction or failure of the control board

How To Fix it:

In case your tankless water heater is failing to stay on, verify the circuit breaker first to check whether it is in the recommended size. Replace any breaker that is larger than the manufacturer recommended. 

Unplug your heater and disassemble it to check the condition of the flow sensor. Replace the bad sensor. After that, don’t forget to verify the heating element as well. The best chances are the heating element is fried out and turns off the unit randomly.

In such a case, you will need to replace the bad heating element. Seek professional help if you’re technically inclined. 

Finally, inspect your water heater for the clogged heat exchanger. In this instance, you’ll need to descale and flush your water heater using the proper method. Wondering how to do so?  

Give a read to our article on why Stiebel Eltron water heater keeps tripping covering all needed step-by-step procedures. 

09. Stiebel Eltron Water Heater Not Heating

If your Steibel Eltron water heater is not heating the water at all, here are some culprits behind this problem. 

  1. Fixtures located far from the water heater or using multiple appliances simultaneously
  2. Having a water heater that is too small to meet the hot water demand.
  3. Not having enough electrical power provided to the water heater.
  4. Incorrect or faulty connection between the water heater and the plumbing system.
  5. Insufficient water flow to trigger the operation of the water heater.
  6. Blockage or malfunction of the flow sensor
  7. Accumulation of dirt or debris in the aerator
  8. Tripped safety thermal cut-out

How To Fix it:

Here is all to deal with if your Stiebel Eltron tankless water heater not producing hot water at all:

First up, check if too many hot water fixtures are running simultaneously for your tankless unit. If so, turn off some of the faucets to let the remaining water get hot. 

In case you suspect that the heater is undersized that your hot water demand, consider upgrading to a higher capacity one.

Check and switch on the circuit breakers. Fix the loose wiring connection and replace the bad breaker. If there is no hot water at all and you don’t hear any audible click when you turn on the heater, this is likely the reason.

Next, inspect the plumbing connection of your house and figure out the faulty connection. Fix it with the help of a professional.

Inspect your water heater and clean out the clogged filter screens, faucet aerators, or shower heads. Clean out the clogged flow sensor and replace the bad one. 

Finally, check out the thermal cut-out switch. If it is tripped, simply resetting the red reset button on the switch will be enough to get your heater back to normal heating operation. 

How To Fix Temperature Sensor Failure Water Heater 

If the temperature sensor in your Stiebel Eltron Tempra Plus water heater is faulty, you will get error code 2 or error code 3 from the heater. 2 means the inlet sensor is faulty, and 3 means the outlet sensor is faulty. 

If you face a temperature sensor failure in your Stiebel Eltron water heater, you need to replace the faulty sensor. Here’s how you do it. 

Step 1: First, disconnect the power source to turn off the power supply to avoid any electrical hazards. 

Step 2: Now you have to remove the access panel of your Stiebel Eltron water heater to reach the temperature sensor. 

Step 3: Once you have removed the access panel, locate the temperature sensor. The temperature sensor in a Stiebel Eltron water heater is attached to the bottom of the heater cylinder. 

locate the temperature sensor of stiebel eltron water heater

Step 4: Carefully disconnect the electrical wires attached to the temperature sensor. And then, gently pull out the temperature sensor from its mounting point.

Step 5: Insert the new temperature sensor into the same location where you removed the faulty sensor. Make sure to buy the new sensor from Stiebel Eltron manufacturer or an authorized dealer. Also, make sure the new sensor matches the specifications of the original one.

Step 6: Reconnect the electrical wires to the appropriate terminals on the new sensor. Make sure the connection is properly tightened and secured. 

Step 7: Replace the access panel cover and turn on the power supply. 

Now the temperature sensor problem is fixed. 

So far I’ve discussed the general problems of Stiebel Eltron. However, below I’ll cover the model-wise issues, So, keep reading. 

Stiebel Eltron Tempra Plus Troubleshooting

If you’re using the Stiebel Eltron Tempra Plus, then you may face different issues. Below I’m discussing all the problems and solutions. Here in the case of problem one, the solution is different for different model users. But for the rest of the problems, the solution is the same. So, Let’s check out…

Problem 1: No Hot Water

If you’re not getting any hot water from your Stiebel Eltron Tempra, there could be a few reasons why:

  1. The circuit breakers for the water heater are switched off.
  2. The water flow is too weak to start the unit.
  3. The flow sensor may be blocked or not moving freely.
  4. There might be a mistake in how the water heater was connected.

How to Fix It:

To solve this, first, make sure the circuit breakers for the water heater are on. The water heater needs power to work, after all.

Next, tankless water heaters need a certain amount of water flowing through them to start heating. If the water isn’t flowing fast enough, the heater won’t turn on. For your convenience here I am providing the minimum water flow required to initiate the respective units:

  • Tempra 12 Trend: 0.37 gpm
  • Tempra 15 Trend: 0.5 gpm
  • Tempra 20 Trend: 0.5 gpm
  • Tempra 24 Trend Plus: 0.5 gpm
  • Tempra 29 Trend Plus: 0.77 gpm
  • Tempra 36 Trend Plus: 0.77 gpm

Also, check the flow sensor. If it’s clogged or stuck, the heater won’t work properly.

Lastly, double-check the water heater’s installation. If it’s not plumbed correctly, that could be causing the problem.

Problem 2: Restricted Water Flow

Sometimes, the hot water may not come out of the faucet properly. This can happen if the filter screen or the heating parts have stuff blocking them.

How to Fix It:

To make the hot water flow better, you should look at and clean both the filter screen and the heating parts.

Caution: When you remove the scale from the heating parts, it’s a good idea to ask a pro for help.

Problem 3: Not Enough Hot Water

If your Tempra Tankless Unit isn’t heating the water enough, it could be due to a few reasons:

  1. The water flow rate is too high.
  2. The unit isn’t getting enough voltage.
  3. The thermal safety cutout has been activated.

How to Fix It:

Here I’m adding a simple guide to fix the problem. 

  1. First, if the water is flowing too quickly, you need to slow it down. Keep adjusting the water flow until the blinking power light on the front cover stops.
  2. Next, make sure the unit is getting the right amount of voltage. The Tempra unit needs between 208V and 240V to work properly.
  3. Lastly, check the thermal safety switches. These are located on top of the copper heating canisters under the front cover. Use something non-conductive, like a pencil with an eraser, to press the switches. If they click when you press them, you’ve reset them correctly.

Problem 4: Stiebel Eltron Tempra Plus Power Light Off 

Stiebel Eltron Tempra Plus water heaters have several safety features designed to protect the unit and prevent potential hazards. If the power light is off, it could be due to various reasons which are given below. 

Whether you are performing a Stiebel Eltron Tempra 29 plus troubleshooting, or any other model, these reasons are common. 

Power Source ProblemCheck and make sure the heater is getting the proper power supply
Tripped Reset ButtonReset the tripped button
Faulty ThermostatReplace the thermostat 

i) Power Source Problem

If there is an issue with the electrical power source supplying the water heater, the power light will be off. This could be caused by a blown fuse, a tripped circuit breaker, or a loose electrical connection. Without a stable power supply, the water heater cannot function and will shut off to avoid damage or unsafe operation. 

How to Fix it:

Here is what you need to check.

  • Check the Circuit Breaker or Fuse. Make sure the circuit breaker is in the “ON” position. Inspect it for signs of damage or being blown and replace it if necessary.
  • Check all electrical connections, including those at the circuit breaker, water heater terminals, and any junction boxes. If there are any loose connections, tighten them.

If the heater is getting power but still there is no power light, go to the next reason. 

ii) Tripped Reset Button

If the safety trips, the power to the heating elements will be cut off. As a result, even if you provide power to the unit, the power light will remain off.

How to Fix it:

Check the reset button and if the button is tripped, you have to reset it in the similar way mentioned later in this article. 

iii) Faulty Thermostat

If the thermostat malfunctions or fails, it can remain in the off position. And, If the thermostat is stuck in the “off” position, the heating elements won’t receive power. As a result, the water heater won’t heat the water. Consequently, the power light will be off.

How to Fix it:

In this case, you have to replace the thermostat in your Stiebel Eltron Tempra Plus. Replacing the thermostat in a water heater is a sensitive task as it controls the temperature of the heated water. The task is complicated as well. So, it is best to get the job done by a professional.  

Tempra Plus Error Code Reporting 

Now let’s check the error codes of Tempra Plus water heater. 

Error CodePossible IssueRecommended Action
2Problem/Failure with inlet temperature sensorCheck the inlet temperature sensor and consider a replacement if necessary. Alternatively, consult a certified technician.
3Failure or issue with outlet temperature sensorCheck and ensure proper connection of the outlet temperature sensor cable to the main control board. Replace the sensor if needed.

Stiebel Eltron DHC Tankless Water Heater Troubleshooting

Now if you’re using the Stiebel Eltron DHC Tankless Water Heater you can also face some common issues. Let’s see why they occur and how to fix them. Also mentioning one thing, this guide is for all DHC water heater models-

ReasonPossible CausesSolutions
No Hot Water and Audible Click# The circuit breaker is off
# Safety thermal cut-out tripped.
# Undersized heater
# Turn on the circuit breaker.
# Reset thermal cut-out.
# Consider replacing the undersized heater.
No Hot Water and No Audible Click# Low water flow to activate the switch.
# The faucet aerator is clogged.
# Partially open the shut-off valve.
# Adjust the flow setting.
# Clean the faucet aerator.
# Fully open shut-off valve.
Water Not Warm Enough# Excessive water flow
# Insufficient voltage
# Reduce water flow.
# Ensure proper voltage

Problem 1: No Hot Water and Audible Click

If you’re experiencing a situation where there is no hot water, but you can hear an audible click when you turn on the water, there are a few potential causes to consider. If the circuit breaker is switched off it can happen. 

Another possibility is that the safety thermal cut-out has been triggered. Finally, it can occur due to an undersized heater. 

How to Fix it:

First, check if the circuit breaker for the water heater is switched off, and if it is, simply turn it on. Now if the problem is with the thermal cut-out, you can reset the thermal cut-out to restore normal operation. Finally, if the problem isn’t any one of them consider replacing the heater with the right one in size.  

Problem 2: No Hot Water and No Audible Click

This problem can occur when the water flow falls below the threshold required to activate the flow switch.

In most cases, insufficient water flow is attributed to a faucet aerator that is obstructed, not fully opening the shut-off valve, or setting the flow rate too low.

How to Fix it:

To fix this problem start by checking the faucet aerator to identify any restrictions. Also, if necessary, clean it to restore unrestricted water flow.

Next, ensure the shut-off valve is fully open.

Lastly, confirm that the flow rate is set optimally. If you need to enhance the flow rate, adjust the flow adjustment screw counterclockwise.

Problem 3: Water Not Warm Enough

When your water heater doesn’t provide enough heated water, it might be due to setting the water flow too high or insufficient voltage reaching the unit.

How to Fix it:

If the water flow exceeds the recommended level or you’ve set it too high, consider reducing it to an appropriate range.

To achieve this, turn the flow adjustment screw clockwise, It’ll help to produce hot water moderating water volume.

Furthermore, ensure that the water heater receives an adequate supply of electricity to function effectively.

In situations where the unit does not receive the necessary minimum voltage to activate, contact a certified electrician to solve the issue. 

Stiebel Eltron DCE Premium Tankless Water Heater Troubleshooting

If you’re facing issues with the Stiebel Eltron DCE Premium water heater then check the below guide. However, before I start let me clarify for you, whatever DCE premium model you use you can apply the basic solution I’ve provided to solve the problem. 

Problem 1: Unit Fails to Start Despite Fully Open DHW Valve

This issue can arise due to 3 reasons. Here are the following reasons:

  1. Lack of power reaching the unit.
  2. Accumulation of dirt or clogs in the tap’s aerator or the shower head.
  3. Interruptions in the water supply can occur if the unit is not vented properly or if the cold water inlet line is not properly connected

How to Fix it:

Now let’s check how you can fix it. 

  1. Ensure there is sufficient power by checking the circuit breakers connected to the unit. If they are off, turn them on in the circuit breaker panel to provide power to the water heater.
  2. In the case of the Stiebel Eltron DCE Premium tankless unit, it may not start if the aerator in the tap or shower head becomes scaled or clogged. To address this, inspect the aerator and clean it if necessary.
  3. Ensure proper venting of the unit and verify the correct connection of the cold water inlet line. 

Problem 2: When You’re Using Hot Water, You Might Briefly Get a Bit of Cold Water.

When using the DCE Premium Tankless Water Heater, you may notice a brief flow of cold water while drawing off hot water. This happens due to the air detector sensing air in the water. It generally causes a temporary pause in heating output.

How to Fix it:

No worries, though. The unit will start again on its own in just 1 minute. You don’t need to do anything to fix it.

Problem 3: Boiling Sounds During Operation

If you hear boiling noises from the unit while it’s working, it might be due to improper venting or low supply pressure.

How to Fix it:

The first thing you’ll have to do is to ensure proper venting to stop the boiling sounds.

When starting the unit, make sure to activate the AE3 safety switch before giving power. The unit won’t turn on without it.

During initial setup, open and close all connected draw-off valves for at least 15 minutes. Also, clear air from pipes and the water heater by running water for 3 minutes.

Lastly, check supply pressure; if needed, increase it. The unit needs at least 26.1 PSI but not more than 145 PSI.

Problem 4: Can’t Set the Required Temperature

The Stiebel Eltron DCE Premium Tankless Water Heater has a safety feature inside to prevent burns. When this safety feature is on, you can’t change the temperature setting.

How to Fix it:

There is no particular fix. It’s better not to try to change this safety feature yourself. It’s better to get help from a professional technician.

Stiebel Eltron DCE Premium Diagnostic Light Codes

If you’re also trying to figure out the meaning of the diagnostic light code then check the below chart. 

Diagnostic LightsMeaningCausesCorrective Actions
No LED is litWater heater fails to heat up# No power reaching the unit
# Faulty PCB
# Ensure all circuit breakers for the unit are turned on.
# Replace the PCB
Green flashing, yellow off, red offNo Domestic Hot Water (DHW)# Clogged aerator in tap/shower head
# Dirty filter screen in cold water inlet
# Unplugged flow meter
# Defective flow meter
# Faulty PCB
# Clean or replace the aerator.
# Clean the filter screen.
# Connect the flow meter wiring to the PCB.
# Replace the flow meter.
# Replace the faulty PCB.
Green flashing, yellow on, red offProgramming unit display off# Loose cable between PCB and programming unit
# Defective cable
# Faulty programming unit PCB
# Faulty PCB
# Check and securely plug in the cable to the programming unit or PCB.
# Replace the cable or the programming unit PCB.
# Replace the PCB.
Green flashing, yellow on, red offOutlet temperature mismatch# Programming unit not plugged in before power on
# Faulty outlet sensor
# Faulty tap
# Defective heating system
# Bad PCB
# Faulty motorized valve
# Perform a reset by turning off the power to the unit.
# Replace the outlet sensor.
# Replace the faulty tap with a new one.
# Replace the heating system.
# Replace the PCB.
# Replace the motorized valve.
Green flashing, yellow off, red onNo DHWAir detectedProlonged draw-off exceeding a minute
Green flashing, yellow off, red onWrench symbol flashing (displays E1 and wrench in fault code display)AE3 safety switch not engaged during initial setupActivate the AE3 Safety Switch by pressing the reset button.
Green flashing, yellow off, red onWrench symbol flashing (displays E2 and wrench in fault code display)AE3 safety switch triggeredCheck and activate the high-limit safety cut-out switch and AE3 Safety Switch.
Green flashing, yellow off, red onSame as before# Defective high-limit safety cut-out switch
# Faulty PCB
# Short circuit in outlet sensor
# Replace the faulty high-limit safety cut-out switch.
# Replace the PCB.
# Inspect and replace the outlet sensor if needed.

How To Maintain Stiebel Eltron Tankless Water Heater For Optimal Performance 

Although Stieble Eltron tankless water heaters don’t require much maintenance, some maintenance is essential to ensure optimal performance, energy efficiency, and longevity. Here are those:

  1. Descale the tankless heater every 6 months to 1 year depending on the mineral buildup intensity. 
  2. If you live in an area with hard water that causes scale buildup, you may need to descale the entire unit. The frequency of descaling will depend on the severity of the scale. Stiebel Eltron recommends using their Flow-Aide System (part # 540000) for this process.
  3. You can install a filter to prevent scale buildup on the cold water supply to the water heater, especially in hard water areas. Stiebel Eltron suggests using the House Pure® WI-HPSECURE-.75 filter (part # 581331) for this purpose.
  4. Using a damp cloth, clean the exterior of the tankless water heater’s housing. Whenever it gets dirty. Avoid using abrasive or corrosive cleaning agents.
  5. Regularly check the filter screen located in the cold water inlet connection. If it’s clogged or damaged, replace it as needed. Make sure to always turn off the power and water supply to the unit before performing this service.

By following these simple maintenance tips, you can ensure optimal performance from your Stiebel Eltron tankless water heater. 

How Do You Reset A Stiebel Eltron Tankless Water Heater

After performing any repair or a power breakage, sometimes you have to reset the Stiebel Eltron water tankless water heater. It is true for both Stiebel Eltron Tempra Plus and Stiebel DCE Premium. 

To reset the Stiebel Eltron tankless water heater, follow these steps. 

Step #1: First, turn off the power to the water heater. 

Step #2: Then locate the black or gray reset button which is on top of each heating vessel. 

Step #3: Press the button firmly and your tankless water heater will be reset. 

Now the water heater should work in a stable condition. 


How to adjust the temperature on a Stiebel Eltron tankless water heater?

Adjusting the temperature on the Stiebel Eltron tankless water heater will differ from model to model. Generally, find out the temperature knob and rotate it right and left to increase and decrease the temperature. 

Does my Stiebel Eltron tankless electric water heater need to be vented?

No, Stiebel Eltron tankless electric water heaters do not need to be vented. They do not use combustion to heat water like gas heaters do. Instead, they use electricity to heat a metal element.

Can I install my own Stiebel Eltron tankless electric water heater?

Yes, you can install your own Stiebel Eltron tankless electric water heater by using the owner’s manual. However, it is not recommended unless you are experienced in working with electrical and plumbing systems. It’s better to consult a certified dealer.

Why is my tankless water heater not firing?

If your tankless water heater is not firing, check the breaker for electric units or ensure the gas valve is fully open for gas-powered units. It’s usually easy to spot these issues while trying to reopen the fuel delivery system.

How many hours a day does a tankless water heater run?

In an average home, new tankless water heaters run about 1-2 hours. On the other hand, older tank-style heaters run 5+ hours daily as they need longer time to heat water. If the heater isn’t running constantly, nothing to be concerned about. 


Here is the complete Stiebel Eltron tankless water heater troubleshooting guide. Hopefully, the article was helpful enough to fix your heater-related issue.

Don’t forget to flush and descale the heater regularly. If you have hard water in your area, the descaling interval should be frequent. 

Also, remember that you may have to act differently when the problem comes with different models. I’ve already mentioned the problems for different models such as Tempra Plus, DHC, and DCE Premium.

Well, you can also check out our complete troubleshooting guide on Camplux Water Heater if you have a Camplux water heater. We’ll be happy to see you there.

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