If your Noritz Takless hot water system keeps tripping the mains, it may indicate an electrical fault or overload; consult a professional for diagnosis and repair.
If your Noritz tankless water heater keeps tripping the mains, you’re not alone. This frustrating issue can leave you without hot water and wondering what’s wrong. The good news? Most causes are fixable with some troubleshooting or professional help.
Why Your Noritz Tankless Heater Trips the Mains
Several issues can cause your Noritz tankless system to trip the electrical supply:
- Overheating (Error Code 20) – The high limit switch activates when water temperature approaches dangerous levels (176°F-205°F)
- Scale buildup – Mineral deposits reduce heat transfer efficiency
- Electrical faults – Loose wiring or component failures
- Venting problems – Blocked exhaust prevents proper combustion
- Gas supply issues – Insufficient gas pressure or flow
Overheating and Error Code 20
The most common reason for tripping is overheating, indicated by Error Code 20. This safety feature activates when:
- Water temperature reaches 176°F-205°F
- The heat exchanger can’t transfer heat properly
- Combustion stops immediately to prevent scalding
As Randy Oshiro from Noritz explains, “These codes diagnose problems that might otherwise go unnoticed until unit failure.”
Scale Buildup: The Silent Killer
Hard water causes scale to accumulate in the heat exchanger. This buildup:
| Problem | Result |
|---|---|
| Reduced heat transfer | Components overheat |
| Restricted water flow | Higher operating temperatures |
| Insulation effect | Heat stays in exchanger |
Regular descaling prevents this issue. For hard water areas, consider a water filtration system.
Electrical Causes
Other electrical issues that may cause tripping include:
- Faulty high limit switch
- Loose wiring connections
- Power surges
- Circuit overload
If resetting the unit doesn’t help, the problem might be electrical. Consider using a surge protector for your system.
Step-by-Step Troubleshooting
Try these steps before calling a professional:
- Reset the unit – Unplug for 30 seconds then reconnect
- Check error codes – Note any displayed codes
- Inspect vents – Ensure exhaust isn’t blocked
- Verify gas supply – Confirm gas valve is open
- Check water flow – Make sure filters aren’t clogged
When to Call a Professional
Contact a licensed contractor if:
- Error codes persist after reset
- You suspect gas supply issues
- The unit needs descaling
- There are combustion abnormalities (Code 90)
As noted in Noritz documentation, “Some resolutions are simpler than others, but you should always err on the side of caution.”
Preventing Future Problems
Keep your Noritz tankless system running smoothly with these tips:
- Annual maintenance – Schedule professional servicing
- Regular descaling – Follow manufacturer guidelines
- Water treatment – Install softener if needed
- Proper venting – Keep exhaust clear
- Monitor performance – Watch for changes in operation
For more information on maintaining your system, check Noritz’s official website or consult their technical support at 866-766-7489.
Remember that persistent tripping could indicate serious issues. As one HVAC expert notes, “If you repeatedly reset without fixing the root cause, you risk permanent damage.” For complex electrical issues, consider consulting resources like HVAC multimeter guides to understand proper testing procedures.
