USA Water quality is supported by its audience. If you buy something through our links, we may earn money from our affiliate partners. Learn more

How to Reset a Rinnai Tankless Water Heater in 5 Steps

Fact checked by Stephen Conklin

how to reset a rinnai tankless water heater

Rinnai is one of the world’s most trusted tankless water heater brands. You’ll never go wrong with their reliable and efficient on-demand heating systems. However, errors can occur. Hence, you must know how to reset a Rinnai tankless water heater to restore its functionality.

We prepared a simplified guide to help you reset your Rinnai unit when the water is not getting hot enough or you experience other tankless water heater problems (i.e., no hot water).

Let’s start.

Table of Contents

Step-by-step to Reset a Rinnai Tankless Water Heater

Step 1. What to prepare


Resetting a Rinnai water heater doesn’t require any tool or material.

However, we recommend preparing the owner’s manual specific to your Rinnai model. For example, you can check the appliance reset instructions on a Rinnai RL75, RL94i, or other designs.

Step 2. Read the Rinnai tankless water heater user guide.


Rinnai provides detailed instructions on managing its appliances. You can start by reading the Rinnai troubleshooting guide specific to your model series.

  • Rinnai typically has no reset button. Users must press other controls to access this function.
  • Understand the control panel’s location and the digital display screen. Some reset the unit by pressing the on/off button, not the dedicated A and B buttons behind the panel.
  • Differentiate between a factory reset and a power cycle. Some technicians call the latter a hard reset.

Step 3. Understand Rinnai’s error code system.


Rinnai has several “error codes” you might see on the digital display. The error code numbers range between 02 and 79. You might even see No Error Code (which indicates a number of potential problems like dirty inlet filter and problematic flow control sensor), or Code LC and Code LC0-LC 9 (meaning heat exchanger’s scale buildup).

But let’s look at the more common ones.

  • 02 – The burner doesn’t operate while in freeze-protection mode.
  • 03 – This code often shows up after a power outage or any electrical supply interruption.
  • 10 – There’s an obstruction in the water heater’s combustion or exhaust.
  • 11 – This error code signifies a potential issue with the tankless water heater’s ignition system, including the pilot light.
  • 12 – There is a potential issue with the gas supply, leading to flame failure.
  • 14 – Airflow obstruction, low water flow, and excessive carbon deposits in the heat exchanger can produce this error code.
  • 16 – The water heater is overheating.
  • 32 – There is a problem with the device monitoring the water temperature.
  • 33 – An issue with the heat exchanger sensor can lead to this error code.
  • 34 – This code indicates a problem with the temperature sensor in the combustion chamber.
  • 00 – Limescale covers and interferes with optimum heat exchanger function.

Step 4. Open the Rinnai tankless water heater front cover.


As stated above, Rinnai tankless water heaters don’t have a dedicated reset button. Instead, you must access the control panel and press the correct buttons while noting the indicator light.

  • Remove the panel cover’s edging.
  • Loosen and remove any hardware you might see on the cover.
  • Open the water heater panel cover.

Step 5. Reset the Rinnai tankless water heater.


With the control panel cover open, you can observe the following steps.

  • If your Rinnai tankless water heater features the Control-R 1.0 system, reset it to its factory settings by pressing and holding the control module’s Connect button. Don’t release the button until the indicator light blinks white.
  • For units with Control-R 2.0, the procedure is nearly identical. However, the LED must blink white and red before you release the Connect button. You must also quickly tap the Connect button three times afterward.
  • You can observe the following procedure to reset error code.
    • Locate the A and B buttons on the control panel and press and hold them for ten seconds until you see “P” in the display.
    • Continue pressing and holding the two buttons for another ten seconds until “PLC” displays on the screen.
    • Wait for the tankless water heater to turn off.
    • Press the Rinnai tankless water heater’s power button to restore function.
  • For error code 55, you can just press the on/off button for five seconds—no need to remove the panel.

Rinnai America Corporation created an instructional video for resetting its tankless water heaters with the Control-R system. Please check it out.


Learning how to reset a Rinnai tankless water heater might seem daunting. However, it’s a skill that every owner of a Rinnai unit must develop and master by heart. We cannot help but overemphasize the owner’s manual’s importance in addressing error codes.

Although this guide offered directions for resetting a Rinnai tankless water heater, nothing can replace the official troubleshooting manual. If you already lost it, please secure another copy.

5/5 - (2 votes)