How to Reset a Rinnai Tankless Water Heater

Quick Answer

Rinnai tankless water heaters support three levels of reset. A soft reset is done by pressing the power button on the controller to turn the unit off, then pressing it again to turn it back on. A hard reset cuts power at the circuit breaker for 30 seconds. A factory reset on the MC-91-2 or similar controllers is performed by pressing and holding the Mode and Set buttons simultaneously for 5 seconds.

Look, a reset is basically a diagnostic tool, not a permanent fix. If you've had a recent power surge or the gas company was messing with lines in your neighborhood, a quick restart usually clears transient faults like Code 11 or 12. But if that code pops back up the second the burners try to kick in, you're probably dealing with real hardware, not a software hiccup. Don't keep mashing that power button.

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How to Reset Your Rinnai Waterheater

Most Rinnai owners go hunting for a dedicated reset button and can't find one. That's because there isn't one. These units reset through the controller interface or the main power supply, and honestly that trips people up constantly. I always tell folks to try the power button first before touching the breaker. It's the gentlest approach and it won't wipe your temperature settings or any stored history.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Error code appears after a transient gas pressure fluctuation40%

Code triggered by a brief power surge or outage24%

Unit needs reset after a repair is completed14%

User wants to verify whether a code was persistent or one-time12%

Error code from an isolated event that has self-resolved10%

Symptoms You May Notice

There's a two-digit error code sitting on the controller display and the water just runs cold no matter what you do.
Hot water cut out completely right after the power flickered for a second, and the unit won't fire even though the breaker looks totally fine.
Gas company shut off your street for a few hours and the heater still won't start even though gas is clearly back on at every other appliance.
A tech just swapped out a component and now the unit sits there powered but not responding to any demand for hot water.
Code showed up once, hasn't come back, but you want to clear it from the display to confirm it was a one-time thing.

Tools Required for Diagnosis

Phone or notepad to photograph and record the error code before resetPhillips #2 screwdriver (only if your breaker panel requires a tool to access)Flashlight if the water heater is in a dark utility closet or crawlspace

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Did the reset not work?

If the problem comes back after following these steps, a component has permanently failed and needs replacement. Check the specific error code your waterheater is showing:

HUB Error →11 Error →12 Error →10 Error →

Frequently Asked Questions

Where is the reset button on a Rinnai tankless water heater?

I get this one on basically every service call. Rinnai doesn't use a physical reset button like you'd find on a garbage disposal or a GFCI outlet. Instead, the computer resets by cycling the power button on the wall controller or by cutting main power at the breaker. It's all handled through the digital interface. There's no panel to pop off and no hidden button behind the unit. If you're used to tank water heaters, the whole setup feels different.

How many times can I reset a Rinnai before I need to call a technician?

If you've had to reset more than twice in a single day, something's actually wrong. Stop after the second attempt. Constantly resetting a unit with a blocked vent or a failing gas valve can cause internal damage or create an unsafe condition. The unit's throwing that code because it's trying to protect itself and your home. At that point you need a tech who can pull the full error history and actually diagnose the root cause instead of just clearing it and hoping.

Will a factory reset delete my temperature settings on a Rinnai?

A standard soft or hard reset keeps your settings safe because they're stored in non-volatile memory, the kind that survives a power cut. But if you do the Mode and Set button combo for a full factory reset, the unit wipes back to the factory default of 120 degrees. You'll need to manually set it back to your preferred temp after. Most people run them at 120 anyway for scalding prevention, so it might not even matter for you.

Can I reset a Rinnai remotely using the app?

The Control-R module is great for changing temps from your phone but Rinnai intentionally limits remote error clearing for safety reasons. You can't clear a hard lockout or a major fault code through the app. You've got to be physically at the unit. That's actually the right call, because you should be standing there to make sure everything looks and smells normal before you restart a gas appliance. Clearing a fault remotely and then leaving for work is not a good idea.

My Rinnai reset itself during the night and lost my temperature setting. Is this normal?

If your display's blank or the clock resets every morning, you've probably got dirty power or a loose connection. I had a job last fall where a failing surge protector was causing the PCB to drop out around 2am every night and the homeowner thought the unit was dying. Took three visits to nail it down. Check that the outlet or hardwire connection is solid and snug. Put a dedicated surge protector on these units. They're sensitive boards and they really don't love noisy or unstable power.

My Rinnai reset but the same code came back within a few minutes. What now?

OK so that means the underlying problem is still there. A reset just clears the fault log, it doesn't fix hardware. If Code 11 keeps coming back, you're probably looking at an igniter, a flame rod, or a gas valve issue. Code 12 means the flame lit but isn't sustaining. Code 31 or 32 usually points to a temperature sensor going bad. Write down the code, stop resetting, and call a tech. At that point resetting is just delaying the inevitable and potentially masking a real safety issue.

Related Rinnai Waterheater Error Codes

Code: HUBRinnai Tankless Water Heater Error Codes: Complete Guide Code: 11Rinnai Code 11: No Ignition Fix for RU and V Series Tankless Heaters Code: 12Rinnai Code 12: Flame Failure During Operation Code: 10Rinnai Code 10: No Gas Supply or Gas Valve Failure

Same Fix on Other Brands

Navien waterheaterHow to Reset a Navien Tankless Water Heater and Clear Error Codes

Models Known to Experience RESET Errors

This repair applies to most Rinnai waterheaters with this error code. Common model numbers include:

RUR98iN, RU199iN, RU98eN, V65iN, RL75iN, RU160iP, RU199iP, RSC199iN

Written by

Raj Patel

HVAC & Water Systems Specialist · 15 years experience

Last verified for technical accuracy on March 14, 2026