Multiple troubleshooting videos dedicated entirely to resetting Rheem tankless units suggest this is one of the most searched-for fixes in the entire product category, and for good reason: a simple reset resolves a meaningful share of error codes without requiring any parts replacement or professional visit.
Resetting a Rheem RTEX-24 typically involves cutting power to the unit at the breaker, waiting a short period, and restoring power, which clears many temporary sensor faults and error codes without requiring parts replacement. If a reset doesn’t resolve the underlying issue, it usually indicates a persistent problem, like insufficient flow, a genuinely faulty sensor, or inadequate electrical capacity, that needs further troubleshooting.
The Basic Reset Procedure
Based on manufacturer guidance and multiple verified troubleshooting resources, the standard reset process for RTEX units generally follows these steps:
Turn off the water supply to the unit first, as a safety precaution before working near any electrical components.
Switch off all three double-pole breakers dedicated to the unit at your electrical panel, cutting power completely rather than just using any on-unit control.
Wait several minutes before restoring power, giving the unit’s internal electronics time to fully discharge and reset.
Switch the breakers back on and restore water supply, then check the digital display for normal operation and confirm the error code has cleared.
When a Reset Actually Works
A reset is most effective for temporary glitches, a sensor momentarily misreading a condition, a brief power fluctuation causing the control board to enter a fault state, or a one-time flow spike triggering an error that doesn’t reflect an ongoing problem. In these cases, cutting power and restarting the unit clears the fault code and normal operation resumes.
When a Reset Won’t Fix the Real Problem
If an error code returns immediately or repeatedly after a reset, that’s a signal the underlying condition causing the fault is still present, not that the reset failed. Based on patterns across verified troubleshooting discussions, recurring errors after a reset commonly point to ongoing issues like insufficient electrical capacity for current demand, a genuinely failing sensor or heating element, mineral buildup interfering with flow sensing, or water flow rate that’s persistently outside the unit’s supported range.
In these cases, repeating the reset procedure over and over won’t resolve anything, the next step is addressing the specific underlying cause, whether that’s cleaning a sensor, adjusting water pressure, or bringing in a professional to properly diagnose the issue.
A Note on Safety During Reset
Because the RTEX-24 operates on 240V circuits with significant amperage, always cut power at the breaker rather than attempting to work on the unit while it’s live. If you’re not fully comfortable working near your electrical panel, this is a reasonable moment to call an electrician rather than risk injury, especially if you’re already dealing with an error that suggests something beyond a simple temporary glitch.
For a full breakdown of what the E5 and other error codes actually mean before you decide whether a reset is even the right first step, see our error codes guide.
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The Bottom Line
Resetting a Rheem RTEX-24 by cutting power at the breaker, waiting, and restoring it resolves many temporary error codes without further intervention. If the same error returns after a reset, that’s your signal to investigate the specific underlying cause rather than repeating the reset process indefinitely.
Frequently Asked Questions
How do I reset my Rheem RTEX-24? Turn off the water supply, switch off all three dedicated double-pole breakers at your panel, wait several minutes, then restore power and water and check for normal operation.
Will resetting my Rheem RTEX-24 fix an error code? It often resolves temporary glitches and sensor misreads, but if the same error returns immediately after a reset, the underlying cause needs to be addressed directly rather than repeating the reset.
How long should I wait before turning the breakers back on? Several minutes is generally sufficient to allow the unit’s internal electronics to fully discharge and reset, though specific manufacturer guidance may vary.
Is it safe to reset my Rheem RTEX-24 myself? Yes, as long as you cut power at the breaker rather than working on the unit while it’s live. If you’re uncomfortable working near your electrical panel, consider having an electrician assist.
What should I do if the error code comes back after resetting? This indicates the underlying issue (insufficient flow, a genuine sensor fault, inadequate electrical capacity, or mineral buildup) hasn’t been resolved and needs specific troubleshooting rather than another reset attempt.
Does resetting the unit clear stored error history? Typically yes, a full power cycle clears the currently displayed error, though this doesn’t fix an underlying issue that will simply trigger the code again if unaddressed.
Can I reset the unit without turning off the water supply? It’s a good safety practice to shut off water before working near the unit’s electrical connections, even though the water supply itself isn’t directly part of the electrical reset process.
How often should I need to reset my Rheem RTEX-24? Under normal operation, resets should be rare. Frequent resets suggest an underlying issue that needs proper diagnosis rather than repeated resetting as a workaround.
Does a reset fix heating element problems? No, a reset addresses temporary electronic faults, not physical component failures like a burned-out heating element, which requires actual part replacement.
Should I call Rheem support before or after attempting a reset? Attempting a basic reset first is reasonable for a first-time error code, but if it doesn’t resolve the issue or the code returns quickly, contacting Rheem support or a licensed professional is the appropriate next step.
References
- Manufacturer and verified troubleshooting guidance for Rheem tankless water heater reset procedures, accessed July 2026
- Verified customer discussions of Rheem RTEX-24 error code and reset experiences, Amazon.com, accessed July 2026: https://www.amazon.com/dp/B01MS9DVEE