If your tankless water heater suddenly stops working, don’t panic—resetting it is often the fastest way to get hot water flowing again. Many of today’s tankless units have built-in safety features and electronic controls. When something goes wrong—a power surge, error code, or unexpected shutoff—sometimes all your system needs is a simple reset. Here’s a complete, easy-to-follow guide on how to reset a tankless water heater, when to do it, and what tools can help keep your system running strong for years.
Quick Picks: Best Tools & Accessories for Tankless Water Heater Maintenance
-
Best Overall:
AstroAI Digital Multimeter – Handy for checking voltage, troubleshooting controls, and safely diagnosing issues. -
Best Budget:
Klein Tools Non-Contact Voltage Tester – Fast and affordable for quick power checks before you reset. -
Best Premium:
My PlumbingStuff Tankless Water Heater Flushing Kit – For descaling and regular cleaning after a reset or error code.
Step-by-Step: How to Reset a Tankless Water Heater
Most tankless water heaters make resetting quick and simple. If you’re getting cold water, a flashing error code, or your system just won’t respond, follow these steps:
-
Locate the Power Button or Switch
Many tankless models (like Rinnai, Rheem, Navien, and Noritz) have a visible reset button on the main panel, often marked “Reset” or with a red color. Others may require you to use the main power switch or circuit breaker. -
Turn the Unit Off
Press the power button or turn the power switch to “off.” If there’s no dedicated button, turn off the breaker for your water heater at the main electrical panel. -
Wait at Least 30 Seconds
Give the system a moment to fully power down. This allows any error states to clear from the electronics. -
Restore Power
Turn the unit back on or flip the breaker back to “on.” Watch the display—most heaters will run a brief self-check or show the default temperature setting. -
Check for Error Codes
If you see an error code or warning light, refer to your model’s manual. Many codes clear automatically after a reset, but persistent codes may indicate a deeper problem. -
Test Hot Water
Open a hot tap and wait a moment. Your heater should ignite, and hot water should flow as normal.
If your tankless heater resets and operates normally, you’re done! If not, keep reading for more troubleshooting tips.
Common Reasons You Might Need to Reset
- Power Surges or Outages: After a storm or flicker, the electronics may need a fresh start.
- Error Codes: Sensor issues, ignition failures, or temperature fluctuations can all trigger a safety shutdown.
- Low Water Pressure: Sometimes, a momentary drop in flow will lock out the unit until it’s reset.
- After Maintenance: Resetting after descaling, filter cleaning, or part replacement can clear old warnings and restore function.
- Unresponsive Controls: If buttons or digital controls freeze, a reset brings them back to life.
Troubleshooting: If Resetting Doesn’t Fix the Problem
- No Power: Check your circuit breaker and verify power at the outlet. Use a voltage tester or multimeter to confirm.
- Persistent Error Codes: Look up the code in your manual. Common codes may mean dirty sensors, blocked vents, or scale buildup.
- No Ignition: Listen for clicking, which means the igniter is trying to fire. No click usually means no power or a faulty igniter.
- Poor Flow or Cold Water: Clean the water inlet filter, descale the heat exchanger, or check for kinks in supply hoses.
- Leaks or Drips: Water around the heater will shut it down for safety. Always fix leaks before resetting again.
- Repeated Lockouts: If your system keeps shutting off, there’s likely an underlying issue—a reset is only a temporary fix.
If your heater refuses to reset or constantly triggers shutdowns, call a licensed technician. Professional service is a smart investment for safety and long-term reliability.
Best Replacement Tankless Water Heaters
If your unit is old, unreliable, or repair costs keep climbing, it might be time for a new tankless water heater. Here are top-rated models for easy upgrades:
Rinnai V65iN Natural Gas Tankless Water Heater
- Compact, indoor installation
- Reliable electronic ignition
- Handles multiple fixtures at once
- Proven for long-term durability
EcoSmart ECO 18 Electric Tankless Water Heater
- Great for apartments, condos, and smaller homes
- Easy digital temperature controls
- Self-modulating for efficient power use
- Lifetime warranty for residential use
Rheem RTGH-95DVLN High Efficiency Tankless Water Heater
- High output for large homes
- Advanced self-diagnostics
- Quiet, efficient, and built to last
- Smart digital control panel
Comparison Table
| Name | Key Features | Specs/Capacity | Price Link |
|---|---|---|---|
| Rinnai V65iN | Natural gas, indoor, compact, reliable | 6.5 GPM, 10-year warranty | View |
| EcoSmart ECO 18 | Electric, self-modulating, digital controls | 2-4 GPM, 18kW, lifetime warranty | View |
| Rheem RTGH-95DVLN | Natural gas, high efficiency, smart diagnostics | 9.5 GPM, 12-year warranty | View |
FAQ: Resetting a Tankless Water Heater
- Where is the reset button on my tankless water heater?
It’s often located on the control panel, sometimes marked in red. On some models, you’ll need to use the circuit breaker instead. - How often can I reset my tankless water heater?
Occasional resets are fine, but frequent shutdowns mean there’s an underlying problem that needs attention. - Will resetting erase my temperature settings?
No, most units keep your settings after a reset. If you notice a change, simply re-enter your preferred temperature. - Can I reset the heater after descaling or maintenance?
Yes, this is recommended to clear any lingering warnings and ensure the electronics start fresh. - Why does my heater need resetting so often?
Frequent resets usually mean there’s an electrical, sensor, or water flow issue. It’s best to have the unit checked by a pro if this continues.
Conclusion
Resetting a tankless water heater is a fast, simple fix for many common problems—from power glitches to minor error codes. With a few easy steps and the right tools, you can restore hot water and peace of mind. Remember: if resets don’t solve your problem, regular maintenance, descaling, and professional checks will keep your tankless system running for years. And if your heater is aging out, upgrading to a new, efficient model is a smart move for comfort and energy savings.