When your hot water suddenly stops working, it can be a stressful surprise—especially when you rely on a Tempra Plus water heater. These German-engineered tankless units from Stiebel Eltron are known for reliability, but like any appliance, they can experience issues.
Understanding how to troubleshoot your Tempra Plus water heater can save you time, money, and cold showers. This guide will walk you through the most common problems, clear step-by-step troubleshooting, and expert tips to keep your water heater running smoothly.
Understanding The Tempra Plus Water Heater
The Tempra Plus series uses advanced flow control technology to keep water temperature constant, even if demand changes. Unlike traditional water heaters with tanks, Tempra Plus heats water only when you need it. This means more energy efficiency and endless hot water—if everything works correctly.
Each model in the Tempra Plus line has a digital display, easy-to-use dials, and electronic safety features. The most popular models are Tempra 12 Plus, 15 Plus, 20 Plus, 24 Plus, 29 Plus, and 36 Plus. All share similar troubleshooting steps, but it’s important to check your user manual for any model-specific details.
Basic Troubleshooting Principles
Before diving into repairs, keep these principles in mind:
- Safety first: Always turn off the circuit breaker before opening your water heater.
- Check the basics: Many problems are simple—like a tripped breaker or closed water valve.
- Observe the display: Error codes or blinking lights often point to the problem.
- Document issues: Write down any error codes, noises, or water conditions you notice.
- Know your limits: If you’re unsure, call a certified technician to avoid making things worse.
Common Tempra Plus Water Heater Problems
Let’s look at the issues Tempra Plus owners face most often. Each section explains symptoms, possible causes, and what steps you should take.
1. No Hot Water
There are few things more frustrating than turning on the tap and getting cold water. Here’s what to check first:
- Power supply: Is the breaker tripped? Is the unit plugged in?
- Water flow: Is the water flow too low to trigger the heater?
- Temperature setting: Is the set temperature too low?
- Error codes: Is the display showing a code?
Troubleshooting Steps:
- Check the circuit breaker in your electrical panel. Reset if needed.
- Inspect the display on your heater for error codes. If blank, power isn’t reaching the unit.
- Turn on a hot water tap fully. Tankless heaters need enough flow to activate. If the flow is too low, the unit won’t fire.
- Adjust the temperature dial higher and test again.
- Examine water valves to ensure both cold in and hot out lines are open.
If these steps don’t work, the problem may be internal—such as a faulty flow sensor, heating element, or control board.
2. Water Not Hot Enough
If your Tempra Plus produces only lukewarm water, consider these causes:
- Incoming water is too cold (common in winter)
- Unit is undersized for your demand (using too many taps/showers at once)
- Temperature limit set too low
- Heating elements not working
Troubleshooting Steps:
- Reduce hot water demand: Run one tap at a time to see if temperature improves.
- Increase the set temperature using the control panel.
- Check for error codes indicating a problem with sensors or heating elements.
- Clean the inlet filter: Sediment can reduce flow and cause lukewarm water.
A non-obvious tip: If you recently installed the unit, check your home’s electrical capacity. Tempra Plus models need high amperage. Undersized wiring can limit heating power.
3. Fluctuating Water Temperature
Does your hot water suddenly turn cold, then hot again? This “temperature swing” is often due to:
- Water pressure changes (such as someone flushing a toilet)
- Clogged filter or flow sensor
- Overloaded unit (too many fixtures at once)
- Inconsistent power supply
Troubleshooting Steps:
- Clean the water filter: Shut off water and remove the inlet filter. Rinse sediment out.
- Test one fixture at a time: If the problem stops, your unit may be undersized.
- Check for voltage drops: If lights dim when hot water is used, have an electrician inspect your wiring.
- Inspect the flow sensor: Mineral buildup can cause erratic temperature changes.
Pro tip: In hard water areas, limescale can coat sensors and elements. Annual descaling helps prevent these issues.
4. Error Codes And What They Mean
The Tempra Plus digital display shows error codes when something is wrong. These codes are your best troubleshooting tool. Here are the most common ones:
| Error Code | Meaning | Action |
|---|---|---|
| E1 | Temperature sensor error | Call for service |
| E2 | Output temperature too high | Check flow rate/filter |
| E3 | Safety cutoff activated | Inspect wiring, call technician |
| E4 | Electronic fault | Reset power, call service if persists |
If you see an error code, always write it down before resetting your unit. In some cases, simply turning the power off and on will clear the code, but if it returns, don’t ignore it.
5. Leaking Water
A leak from your Tempra Plus is rare but serious. Even a small drip can damage electronics.
Common leak sources:
- Inlet/outlet connections: Loose fittings or worn washers
- Internal heat exchanger: Corrosion or freeze damage
- Pressure relief valve: Opening due to high pressure
Troubleshooting Steps:
- Turn off power and water to the unit immediately.
- Inspect connections: Tighten or reseal as needed.
- Check the relief valve: If water is hot, the system may be over-pressurized.
- Look for corrosion: If you see rust or mineral buildup inside, call a professional.
Expert insight: Never operate the unit with a leak. Water can short-circuit electronics and void your warranty.
6. Unit Will Not Power On
If the digital display is blank, the heater may not be getting power.
Possible causes:
- Tripped breaker
- Loose wiring
- Faulty control board
Troubleshooting Steps:
- Check your home’s breaker panel. Reset the breaker for your water heater.
- Inspect the power supply cable for damage.
- Open the unit cover (power off first!) And check all wire connections. Look for burnt or loose wires.
- Test with a multimeter: If you’re comfortable, confirm voltage at the terminal block.
If you find damage inside, stop and call a qualified electrician or service tech.
7. Strange Noises
Tankless water heaters are usually quiet. If you hear clicking, hissing, or banging, there may be an issue.
- Clicking: Normal relay operation or mineral buildup on flow sensor
- Hissing: Scale buildup on heating elements
- Banging: Water hammer (sudden pressure changes)
Troubleshooting Steps:
- Clean the inlet filter to remove debris.
- Flush the heat exchanger with vinegar to remove limescale.
- Install a water hammer arrestor if you hear loud bangs after shutting off taps.
Non-obvious tip: Even small amounts of air in the lines can cause noise. Bleed your plumbing system if you’ve done recent repairs.
Routine Maintenance For Tempra Plus Heaters
Preventative maintenance keeps your water heater running longer and more efficiently. Here’s what you should do:
- Clean the inlet filter every 6-12 months, more often in areas with sediment.
- Descale the heat exchanger annually, especially in hard water regions.
- Inspect for leaks and tighten connections as needed.
- Check the display for error codes during regular use.
If you’re comfortable, you can perform these steps yourself. Otherwise, schedule a yearly checkup with a professional.
When To Call A Professional
While many issues are easy to fix, some require a trained technician. Call for help if:
- You see persistent error codes (E1, E3, E4).
- There’s water leaking inside the unit.
- The heater trips the breaker repeatedly.
- You smell burning or see scorch marks.
- You aren’t sure about any electrical work.
Attempting advanced repairs without proper skills can be dangerous and may void your warranty.
Tempra Plus Vs. Other Tankless Water Heaters
To help you understand where Tempra Plus stands, here’s a comparison with two other popular brands:
| Feature | Tempra Plus | Rheem | EcoSmart |
|---|---|---|---|
| Flow Control Technology | Advanced digital | Basic | Basic |
| Max Temperature Rise (°F at 2 GPM) | 65-80 | 65 | 60 |
| Display Type | Digital | Digital/Analog | Digital |
| Warranty | 7 years leakage/3 years parts | 5 years | Lifetime (limited) |
| Country of Origin | Germany | USA | China |
The Tempra Plus offers better temperature stability and build quality, but does cost more upfront.
Practical Tips For Owners
Many Tempra Plus issues come down to installation or use. Here are some real-world tips:
- Match the unit size to your hot water needs. Oversizing won’t save money; undersizing leads to cold showers.
- Avoid running too many fixtures at once. Even high-powered units have limits.
- Know your water quality. Hard water shortens heater life—consider a softener if your area is known for scale.
- Keep your manual handy. It often has quick answers for common codes and settings.
- Register your warranty after purchase for faster service.
Non-obvious insight: Some users install their Tempra Plus far from the main water line, causing long wait times for hot water at distant taps. Placing the unit closer to bathrooms or kitchens reduces this delay.
Understanding Flow Rate And Sizing
One reason for troubleshooting is improper sizing. The Tempra Plus must be sized for your climate (incoming water temperature) and simultaneous hot water use.
Example Sizing Table
| Model | Power (kW) | Max Flow (GPM at 50°F Rise) | Recommended Use |
|---|---|---|---|
| Tempra 12 Plus | 12 | 1.5 | 1 sink, 1 shower (warm climates) |
| Tempra 24 Plus | 24 | 3.0 | 2 showers, 1 sink |
| Tempra 36 Plus | 36 | 4.0 | 3 showers, 1 sink |
If your water is colder, flow rates decrease. Always choose a model that can handle your peak demand.
Electrical Requirements
Tempra Plus heaters are powerful machines. They require:
- 240V power supply
- Dedicated double-pole breakers (2 per unit for larger models)
- Heavy gauge wiring (usually #6 or #8 AWG)
Improper wiring is a frequent cause of trouble. If you’re not sure, have a licensed electrician check your installation.
Resetting Your Tempra Plus
Sometimes, a simple reset fixes many problems. Here’s how:
- Turn off the breaker to cut power.
- Wait 30 seconds.
- Turn the breaker back on.
- Test the unit by opening a hot tap.
If the problem returns, further troubleshooting is needed.
Water Quality Issues And Their Effects
Poor water quality can damage any tankless heater. Common problems:
- Sediment: Blocks the inlet filter, causes low flow.
- Limescale: Coats heating elements, reduces efficiency.
- Corrosion: Damages internal components.
In hard water areas, install a pre-filter or water softener. Descale the unit at least once a year to keep it running smoothly.
Winter And Freezing Concerns
Tempra Plus units are not freeze-proof. If installed in a cold location (like a garage), freezing can split the heat exchanger.
- Insulate pipes leading to and from the unit.
- Never turn off power in winter—internal sensors and relays help protect against freeze damage.
- Drain the unit if you’ll be away for an extended period in cold weather.
Advanced Troubleshooting: Inside The Unit
If you’re comfortable and have turned off all power, you can check inside for these issues:
- Loose connectors: Wiggling wires can cause intermittent operation.
- Burn marks or melted insulation: Indicates overheating or short circuit.
- Mineral buildup: White chalky deposits signal a need for descaling.
Caution: Never touch the circuit board or heating elements without proper knowledge.
Warranty And Support
Stiebel Eltron offers strong warranties, but only if you follow installation guidelines and maintenance schedules. Keep your receipts and register your product online for easy support. For detailed technical info, the official Stiebel Eltron website offers manuals and troubleshooting guides.
Frequently Asked Questions
Why Does My Tempra Plus Water Heater Show Error Code E1?
The E1 code means there’s a problem with the temperature sensor. This often happens if the sensor becomes disconnected or fails. Turn off power, wait, and restart the unit. If the code returns, call a technician to replace the sensor.
How Often Should I Clean The Inlet Filter?
Clean the inlet filter every 6 to 12 months. If you have hard water or notice reduced hot water flow, check it more frequently. Regular cleaning prevents sediment buildup, which can cause performance issues.
Can I Install A Tempra Plus Heater Myself?
Tempra Plus installation involves high-voltage wiring and plumbing. If you’re not experienced with electrical work, hire a licensed professional. DIY mistakes can be dangerous and may void your warranty.
Why Is My Water Temperature Unstable?
Unstable temperature is usually caused by water flow changes, clogged filters, or mineral buildup. Try cleaning the inlet filter and descaling the unit. Make sure you’re not running too many hot water fixtures at once.
Is The Tempra Plus Water Heater Energy Efficient?
Yes, Tempra Plus heaters are highly energy efficient because they heat water only when needed. The advanced flow control keeps temperatures steady and reduces wasted energy compared to tank models.
A well-maintained Tempra Plus water heater can provide years of reliable hot water. By understanding how to troubleshoot common issues and when to call for help, you’ll enjoy more comfort and peace of mind. Remember—regular maintenance and proper installation are the best ways to avoid problems in the first place.
