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Tankless water heaters are highly efficient and reliable, but like any appliance, they can experience malfunctions. Unlike traditional storage water heaters, tankless units rely on electronic components and sensors to regulate performance. When an issue arises, the system generates an error code that helps diagnose the problem.
Understanding tankless water heater error codes is crucial because they offer a direct indication of what might be wrong — whether it’s a gas supply issue, a blocked vent, or a faulty sensor.
What Are the Tankless Water Heater Error Codes?
Error codes provide a structured way to approach troubleshooting. Instead of guessing what’s wrong, you can systematically check components based on the error message. Many minor issues, such as flame failures or ignition problems, can be resolved without professional assistance. However, some complex errors, such as gas valve failures or heat exchanger blockages, require expert intervention.
Additionally, error codes can help prevent costly breakdowns. If you address minor issues promptly, you can extend the lifespan of your tankless water heater and ensure optimal efficiency. Ignoring warning signs can lead to complete system failure, resulting in expensive repairs or replacements.
This guide will cover the most common tankless water heater error codes, their causes, and how to fix them. If your tankless water heater isn’t functioning correctly, refer to this guide before calling a professional.
Common Tankless Water Heater Error Codes and Their Meanings
Below, we have gathered the most common tankless water error codes, categorized by the type of problem they indicate, along with troubleshooting steps.
Ignition and Flame Issues
Code | Issue | Troubleshooting |
|---|---|---|
11
| No Ignition
| Ensure gas supply is on, check gas pressure, bleed air from gas lines, verify igniter operation, inspect wiring harness. |
12
| Flame Failure
| Check gas supply, inspect flue outlet for blockages, verify proper venting materials, clean flame rod, inspect wiring harnesses. |
72
| Flame Sensing Device Fault
| Ensure flame rod is in contact with flame, check for carbon build-up, inspect wiring connections, clean flame rod. |
Airflow and Exhaust Problems
Code | Issue | Troubleshooting |
|---|---|---|
10
| Air Supply or Exhaust Blockage
| Ensure vents are not blocked, check fan for obstructions, verify vent length limits, inspect condensation collar. |
34
| Combustion Air Temperature Sensor Fault
| Check for airflow restrictions, inspect sensor wiring, clean scale buildup, verify fan blade condition. |
61
| Combustion Fan Failure
| Ensure fan turns freely, inspect wiring for loose connections, measure motor resistance. |
Temperature and Heat Exchanger Issues
Code | Issue | Troubleshooting |
|---|---|---|
16
| Over Temperature Warning
| Check for airflow restrictions, inspect heat exchanger for scale buildup, ensure proper water flow. |
32
| Outgoing Water Temperature Sensor Fault
| Inspect sensor wiring, measure resistance, clean or replace sensor. |
33
| Heat Exchanger Outgoing Temperature Sensor Fault
| Inspect sensor wiring, measure resistance, clean or replace sensor. |
14
| Thermal Fuse
| Verify gas type, check air restrictions, inspect combustion chamber for debris, flush heat exchanger. |
LC
| Scale Build-up in Heat Exchanger
| Flush heat exchanger, follow manufacturer’s descaling instructions. |
Water Flow and Valve Issues
Code | Issue | Troubleshooting |
|---|---|---|
65
| Water Flow Control Fault
| Turn off water immediately, check control valve, contact a technician if issue persists. |
No Code
| No Water Flow When Activated
| Clean inlet water filter, verify minimum flow rate, inspect turbine, check for reversed hot/cold lines. |
Electrical and Control System Errors
Code | Issue | Troubleshooting |
|---|---|---|
02
| No Burner Operation During Freeze Protection Mode | Service call required. |
03
| Power Interruption During Bath Fill
| Turn off hot water taps, press ON/OFF twice. |
52
| Modulating Solenoid Valve Signal Abnormal
| Inspect valve wiring harness, measure coil resistance. |
71
| Solenoid Valve Circuit Fault
| Inspect solenoid wiring, measure valve resistance. |
By understanding these error codes and their solutions, you can quickly diagnose issues and determine whether troubleshooting is possible or if professional service is needed.
Curious about the cost of the new tankless water heater installation? Check out our previous guide via the link below.
https://thehvacservice.ca/understanding-tankless-water-heater-installation-costs/
What to Do When There’s No Error Code, but the Unit Isn’t Working
Sometimes, a tankless water heater may fail to operate without displaying an error code. This can be particularly frustrating, but there are a few common culprits to check.
Check Water Flow
Tankless water heaters require a minimum flow rate to activate. If the flow is too low, the unit won’t turn on. Make sure your faucets are fully open and there are no clogged aerators or filters.
Inspect the Inlet Water Filter
Many units have a filter on the cold water inlet to prevent debris from entering the system. If this filter is clogged, it can restrict water flow and cause the heater to shut down.
Verify Electrical Connections
If the unit has no power, check for tripped circuit breakers or blown fuses. Ensure that the power cord is securely connected.
Look for Plumbing Crossovers
In some cases, hot and cold water lines may be incorrectly installed or there may be a “bleed-over” issue within the plumbing system. To check for this, turn off the cold water supply to the heater and open a hot water tap. If water still flows, there is likely a plumbing crossover issue that needs to be addressed.
When to Call a Professional for Tankless Water Heater Repairs
While many error codes can be resolved with basic troubleshooting, there are some situations where professional tankless water heater repair is required.
- Gas Supply Issues: If you suspect a gas leak, turn off the gas supply immediately and call a licensed technician. Gas leaks are dangerous and should only be handled by professionals.
- Heat Exchanger Problems: If your unit repeatedly displays an LC (scale buildup) error, flushing the heat exchanger might not be enough. Severe scaling can lead to permanent damage, requiring a replacement.
- Electrical Failures: Issues such as short circuits, faulty PC boards, or damaged wiring should be diagnosed and repaired by a trained electrician or technician.
Persistent Error Codes: If an error code keeps appearing despite following troubleshooting steps, the underlying issue may be more serious. Continuing to operate the unit in this state could lead to further damage.
Conclusion
No matter what issue you’re facing with your tankless water heater, our expert team specializes in diagnosing and repairing all types of tankless water heater problems quickly and professionally. Contact us today through the link below, and let us help you get your hot water back on track!
FAQs
1. Why isn’t my tankless water heater igniting?
If your water heater isn’t turning on, the issue might be with the gas supply, low water pressure, or a malfunction in the ignition system. Check if the gas valve is open and ensure the gas pressure meets the manufacturer’s requirements. If you have an electric water heater, check if the circuit breaker has tripped. It’s also worth checking the cold water inlet filter—if it’s clogged, the flow may be insufficient to trigger heating.
2. What to do if my water heater shows error "11" (no ignition)?
Error 11 indicates an issue with the burner ignition. Check if the gas is supplied and the valve is open. Ensure there is no air in the gas line, as this can prevent proper ignition. If the gas supply is fine, inspect the spark electrode for soot or damage. If the issue persists, contact a professional.
3. Why does my water heater show error "LC" (scale buildup in the heat exchanger)?
The LC code means there is mineral buildup in the heat exchanger. This reduces heating efficiency and can lead to overheating. It’s recommended to clean the heat exchanger using a solution of vinegar or citric acid (depending on the manufacturer’s instructions). If the error reappears shortly after cleaning, the water may have high hardness, and installing a filtration system is advised.
4. How to fix error "10" (air intake or exhaust issues)?
Error 10 indicates a disruption in air circulation. Check for blockages in the chimney or intake pipe. Make sure the ventilation pipes are properly connected and free of bends. If your water heater is installed in an enclosed space, ensure there is adequate fresh air intake.
5. Why does my water heater suddenly shut off while operating?
This could be due to overheating, insufficient water flow, or issues with the gas supply. If error code 16 (overheating) is displayed, check the heat exchanger for scale buildup. Also, ensure the water pressure meets the water heater’s requirements, as low flow can cause the unit to shut off. If the problem persists, check the water temperature sensor.
6. What to do if error "32" (temperature sensor failure) appears on the display?
Error 32 indicates a problem with the temperature sensor at the output. Check the sensor connection—make sure the contacts are securely attached. If the issue persists, measure the sensor’s resistance with a multimeter and compare it with the rated values in the user manual. If there is a discrepancy, replace the sensor.
7. Why is my water heater showing error "61" (fan malfunction)?
Error 61 means the fan is not working properly. It might be clogged or blocked by foreign objects. Turn off the unit and inspect the fan for blockages. Check if it spins freely. If the fan is in good condition but the error persists, measure the motor’s resistance and ensure the voltage at its contacts is normal.
8. How to fix error "14" (overheating or burnt thermal fuse)?
Error 14 indicates system overheating. This could be caused by insufficient ventilation, dust accumulation in the combustion chamber, or the wrong type of gas. Check the heat exchanger for blockages, clean the filters, and ensure the water heater is installed according to the manufacturer’s specifications. If the thermal fuse is blown, it needs to be replaced.
9. What to do if my water heater shows no errors but isn’t heating water?
If the unit isn’t showing an error code but is not heating water, check several factors:
- Is the gas valve open?
- Is the water flow sufficient to activate heating?
- Is the water inlet filter clogged?
- Are the electrical connections intact?
If everything seems normal, the temperature sensor may be faulty, or the heat exchanger may be clogged with scale.
10. When should I call a tankless water heater repair professional?
You should contact a professional if:
- Errors persist even after addressing potential causes.
- There are signs of a gas leak or a suspicious odor.
- The water heater doesn’t turn on despite proper water and gas supply.
- There’s a failure in the electronic system (errors related to the control board).
Regular maintenance will help avoid major breakdowns and extend the lifespan of your device.
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