The reset button on a Rheem tankless water heater is a safety feature designed to restore normal operation after an error or temporary fault. Understanding when to use the reset function, how to perform it correctly, and what to do if issues persist can prevent water heater downtime and costly service calls. This guide explains the reset button’s role, common fault indicators, and step-by-step reset procedures tailored to Rheem tankless models used in American homes.

What Is The Reset Button On A Rheem Tankless Water Heater

Rheem tankless water heaters use a diagnostic reset feature to clear minor faults and reinitialize the control board. The reset button, sometimes labeled “Reset” or represented by a recessed button, is part of the unit’s safety system. Its purpose is to interrupt power to the electronics momentarily, allowing the system to recalibrate after a fault such as an error code related to flame detection, high/low water temperature, or ignition failure. If a fault persists after a reset, it indicates a deeper issue that requires further inspection.

Common Signals That Trigger A Reset

Typical fault indicators that prompt homeowners to consider a reset include erratic temperature readings, intermittent hot water, or an error code displayed on the unit’s panel. Some models show codes like “A6,” “E1,” or other fault identifiers, which guide troubleshooting steps in the owner’s manual. Before initiating a reset, users should note the displayed code and assess accompanying symptoms such as unusual noises, water leaks, or a sudden drop in hot water supply. A reset should be a first step for minor glitches, not a substitute for professional diagnosis when problems persist.

When To Use The Reset Button

The reset button is appropriate for temporary or non-recurring faults that do not indicate a persistent mechanical problem. If the unit powers off unexpectedly or an error code appears without a pattern, a reset can restore normal operation. However, if the issue reoccurs after a reset—especially within 24 hours—it signals a more serious issue such as gas supply problems, venting obstructions, mineral buildup, or a failing flame sensor. In such cases, shut off power to the unit and consult a licensed technician promptly.

Step‑By‑Step: How To Reset A Rheem Tankless Water Heater

Note: Procedures may vary slightly by model. Always consult the user manual for model-specific instructions. The following steps cover a common reset method used on many Rheem tankless units.

Turn off the hot water outlet from the unit and switch off the electrical supply to the heater at the service panel or disconnect switch.
Wait 30 seconds to 1 minute to ensure the electrical circuit fully discharges.
Restore power to the unit while ensuring the gas supply remains on and venting is unobstructed.
Attempt to operate the unit by selecting a hot water setting. If an error code appears, observe the code for reference.
Press and hold the reset button (or press the button once, depending on the model) for 3–5 seconds if the button is accessible. Release and wait for the unit to reinitialize.
Observe the display for a normal operating status and confirm hot water temperature behavior returns to expected levels.

Important considerations: do not reset the unit repeatedly in a short period; repeated resets may mask ongoing issues and can cause mineral buildup or safety concerns. If a reset does not clear the fault or the unit shuts down again, contact a professional technician for further inspection.

What To Do If Reset Doesn’t Solve The Problem

If the reset button resolves the fault temporarily but the problem returns, the underlying cause may involve mineral buildup, gas supply, venting, or faulty sensors. Potential checks include:

Inspect the water supply lines for pressure or flow issues; ensure there is adequate incoming water temperature and flow rate required by the model.
Examine venting for obstructions, kinks, or improper termination that could impair combustion or exhaust.
Check gas supply valve and regulator for consistent pressure, especially for gas-fired models.
Consider mineral scale buildup; sediment filters and occasional flushing may be necessary in hard-water regions.
Inspect electrical connections, fuses, and the circuit breaker to rule out intermittent power problems.

For persistent problems, record the error codes, environmental conditions, and recent changes (water temperature settings, new fixtures, or recent power outages) and share them with a licensed technician. Maintaining a written log helps technicians diagnose faults faster and reduces downtime.

Maintenance Tips To Prevent Frequent Faults

Schedule annual professional inspections of Rheem tankless units to verify venting, gas pressure, and combustion air adequacy.
Flush the system per the manufacturer’s recommendations, typically every 12–24 months, to remove mineral buildup.
Use a quality water conditioner in hard-water areas if recommended by the manufacturer to minimize scale formation.
Keep the surrounding area clear of dust, debris, and flammable materials to prevent heat-related or ignition-related faults.
Record model number, serial, and service history for quick reference in future diagnostics or warranty claims.

Safety Considerations When Working With Rheem Tankless Water Heaters

Working with gas-fired or electric boilers involves safety risks. Always shut off electrical power and gas supply before performing resets or any maintenance. If there is any sign of gas odor, unusual flame color, or potential carbon monoxide risk, evacuate and contact emergency services and the utility provider. Do not bypass safety devices or attempt makeshift repairs; rely on qualified technicians for complex issues.

Frequently Asked Questions

What does a reset do on a Rheem tankless water heater? It clears temporary faults and reinitializes the control board after an error, potentially restoring normal operation.
Can I reset the Rheem unit when it’s leaking? No. Water leaks indicate a separate fault that requires addressing before attempting a reset.
Is it normal to hear popping or clanking sounds after a reset? Occasional sounds can occur during ignition or cooling, but persistent or loud noises warrant inspection by a professional.
How often should I reset the unit? Only when a fault code or abnormal operation justifies it. Frequent resets suggest an underlying issue.
Does a reset fix mineral buildup? A reset does not remove mineral buildup; regular flushing and descaling are needed for hard-water conditions.

Key Takeaway: The reset button on a Rheem tankless water heater is a safe first-step diagnostic tool for temporary faults. Use it judiciously, follow model-specific instructions, and seek professional help if faults persist or reappear after resets. Regular maintenance and proper installation are essential to maximize reliability and avoid unnecessary downtime.