Troubleshooting Noritz
Tankless Water Heaters 
and Error Codes

This article answers the question, what to do if you see an error code on the panel display of the Noritz NRC111 water heater and its remote controller. See how Noritz error codes can help you fix the water heating problem.

Noritz error codes explained

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Most of the Noritz water heaters come with advanced technology and intelligent electronics, which is a great help in troubleshooting heating problems.

The LCD display found on the control panel or remote controller provides a visual contact when the failure occurs. The numerical error code will appear, and it will flash on display.

Problems such as no hot water, not enough hot water, flame loss, water too hot or cold, temperature fluctuation are just some of the issues identified through the error codes.

Before attempting to solve the problem, it will be assumed that the Noritz model was correctly installed, per codes and manufacturer instructions. The gas type that is used is natural gas.

Below is the list of the most common error codes, where Noritz NRC111 was taken as an example and where some codes apply to other models.

Error code 10

Problem: Power drops or gas combustion continues even after the unit is turned off.

Action: If the water heating system has recirculation, try to keep the temperature with a difference of 10 degrees. If the combustion continues, check if any foreign body, such as oil/grease, is on the burner. To reset the code, turn the unit off and on.

Error code 11

Problem: The error code 11 is related to ignition failure.

Action: The gas pressure should be checked for the correct values. Check for any obstructions in the vents as the unit might not be removing the products of combustion properly, or the fresh air supply is blocked. If the ignition rod is dirty, remove any accumulated debris; also, check for loose wiring in the ignition.

Error code 12

Problem: The flame was detected, but it becomes very low, or it gets extinguished.

Action: Check that there is enough air coming, so the proper gas combustion is established. Ensure that the flame rod/sensor is not covered with the debris, and if it is, clean it or replace it if necessary.

Error code 14

Problem: The problem is with the thermal fuse. This is a safety element and must be replaced if broken.

Action: If there is an obstructed airflow in the vent system, the water heater will operate with poor combustion. Also, check for the clogged heat exchanger due to the limescale or other impurities from the poor water quality. Eliminate the cause of the problem by cleaning or replacing the heat exchanger.

Error code 16

Problem: The outgoing hot water temperature is too high.

Action: Check the gas pressure and adjust it if it is needed. The heat exchanger has to be cleaned from the limescale. Reset the error code by unplugging the power and plugging it back in after approximately 20 seconds.

Error code 20

Problem: The high limit switch activates due to overheating.

Action: This problem is usually resolved by descaling the heat exchanger, but first check if the problem is with the high limit switch, and replace it if broken.

Error code 29

Problem: The neutralizer does not drain the condensate properly, so the water level exceeds the correct level.

Action: Ensure proper draining of the neutralizer (clean it if it is blocked) or clean the water level sensor from the moist. Also, check that the condensate piping is sized correctly and with the right slope.

Error codes 31 and 32

Problem: Problem with the inlet (cold water side) or outlet (hot water side) thermistor.

Action: Check the elements for the proper work.

Error code 33

Problem: Another problem with the thermistor, but this time on the heat exchanger.

Action: Replace if broken.

Error code 59

Problem: Problem with the combustion due to the low gas BTU input.

Action: Check the gas pressure and make the necessary adjustments if needed. If the unit is installed above the recommended elevation, make sure to make the proper adjustments. Make sure there is no blockage in the venting system or debris on the burner.

Error code 61

Problem: Fan failure

Action: Use the voltmeter to check the voltage on the fan. If the voltage is OK and per specs, check the fan operation and circuit board.

Error code 65

Problem: Main flow control valve

Action: Check the main servo on the valve for blockage, failure and replace it if needed.

Error code 66

Problem: Bypass flow control valve

Action: The same solution as for the above error code, except checking the main valve servo, check the bypass servo.

Error code 70

Problem: Circuit board failure

Action: Replace it if faulty

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Error code 71

Problem: Gas valve drive circuit

Action: Use the voltmeter to check the voltage on the circuit board and replace it if there is a failure. The error code 71 is often seen when the battery backup or generator is used, so there is a different voltage supply.

Error code 72

Problem: Flame rod detection abnormality

Action: Check for the correct grounding and flame detection circuit on the circuit board.

Error code 73

Problem: Issues with the settings on the circuit board

Action: The circuit board needs proper programming, or the dip switch was changed when the power was supplied to the water heater. You can reset the error code by disconnecting the power for 30 seconds and plugging it back in.

Error code 76

Problem: No communication in multi-system setup

Action: Check the quick connect cord and reset the unit by disconnecting the power.

Error code 760

Problem: Remote controller functionality

Action: Reset the unit. Check the wiring connection and that only one remote is used.

Error code 90 and 99

Problem: Problem with the gas combustion

Action: Check for the obstructed venting, improper gas burning (flame shape and color change). Ensure the water heater gets the recommended gas pressure and a proper mixture of fuel and air (per specs). After fixing the problem, reset the error code by disconnecting the unit.

Error code 92 and 93

Problem: Neutralizer life cycle is at the end of its life cycle

Action: Replace the neutralizer and reset the burner timer.

If any of the Noritz error codes appear on the screen or the unit doesn't show any but has problems, it is recommended to contact the technical service from Noritz or a licensed technician. The above list of the error codes and presented solutions of the issues are just for reference.

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