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Noritz tankless water heater error codes

Noritz tankless water heater codes as Noritz America lists them, each with its meaning and the first safe check.

12, EC12
A flame loss: the unit detects a flame
16, EC16
The outlet water temperature spiked to an abnormally
29, EC29
A problem draining condensate from the unit. This

Exact codeDocumented meaningFirst safe checkVerificationStop condition

Part of Consumer-device error codes by manufacturer and product guide

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Noritz tankless water heater · exact code

Noritz tankless water heater code 11, EC11: meaning and exact next steps

11, EC11 means An ignition failure: the unit recognizes a demand for hot water but cannot ignite, or it ignites and fails to detect the flame with the flame rod. Noritz says it usually means no spark or insufficient gas.

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Noritz tankless water heater code 14, EC14: meaning and exact next steps

14, EC14 means A significant overheat of the heat exchanger tripped the thermal fuse and shut the unit down. Noritz says the thermal fuse is a one-time part that is physically broken once it trips.

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Noritz tankless water heater code 20, EC20: meaning and exact next steps

20, EC20 means The high limit switch has been triggered. It trips if water in or leaving the heat exchanger approaches 176 to 205 degrees Fahrenheit. Combustion stops immediately and the unit closes the water control servo.

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Noritz tankless water heater code 73, EC73: meaning and exact next steps

73, EC73 means A circuit board setting problem, triggered by a jumper or dip switch changed while power was supplied, or an improperly programmed board. It applies to all models.

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Noritz tankless water heater code 93, EC93: meaning and exact next steps

93, EC93 means The built-in condensate neutralizer has reached the end of its effective lifespan. Performance may be reduced until it is replaced. It applies to certain condensing models such as the NRC111 and NCC199.

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Noritz tankless water heater code 94, EC94, EC941, EC942: meaning and exact next steps

94, EC94, EC941, EC942 means The exhaust temperature is too high on a condensing unit. On smaller units with a display window it appears as EC941, a warning when exhaust exceeds 182 degrees Fahrenheit that limits input to 77,000 BTU or less, or EC942, a shutdown when exhaust exceeds 191 degrees Fahrenheit.

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Every code

Every Noritz tankless water heater code: what it means and what to do

12, EC12
16, EC16
29, EC29
45, EC45
67, EC67
71, EC71
760, EC760
90, EC90
903, EC903
91, EC91
92, EC92
C1, C1#

Noritz tankless water heater code 12, EC12

A flame loss: the unit detects a flame but the flame is extinguished during operation (a weak flame).

Confirm the gas is fully on and, if the unit is direct vent, that the exhaust is not being drawn back into the intake.

Noritz says most of the code 11 troubleshooting applies: clean the flame rod and confirm enough gas. Improper venting can also cause it, especially on direct-vent units where the air intake draws in the unit's own exhaust; on the NR83DVC and NR98DVC models only Noritz concentric venting may be used, and missing or damaged o-rings on the 3-inch exhaust pipe can cause 12. Noritz recommends checking inlet gas pressure three ways: static, dynamic and max dynamic, always above the minimum on the rating plate. Gas checks are professional work.

Noritz tankless water heater code 16, EC16

The outlet water temperature spiked to an abnormally high value. The heater restricts its water flow as a precaution.

Unplug the heater, wait 20 seconds and plug it back in once.

Noritz says the code is reset by unplugging the heater for 20 seconds. Its listed common causes are scale in the heat exchanger and water components, improperly adjusted manifold pressures, and the wrong gas type.

Noritz tankless water heater code 29, EC29

A problem draining condensate from the unit. This code applies only to Noritz high-efficiency condensing models with PVC, CPVC or polypropylene venting.

Check that the condensate drain line is not kinked, blocked or frozen.

Noritz says the drain line must be plastic, at least 1/2 inch inside diameter, as short and direct as possible, sloped toward the drain, with no additional trap because the unit has one, and that condensate is acidic and may need a neutralizer. A line run outside can freeze and back up, causing 29.

Noritz tankless water heater code 45, EC45

An internal water leak. This code is specific to the NRCP and CB models: a leak sensor at the bottom behind the circuit board tripped.

Turn off the water to the unit and look for water or dampness at the base.

Noritz says to dry out the well and sensor and look for signs of a leak; a leaking part must be replaced. With no obvious water source it may be condensation, but if EC45 keeps returning there is an internal leak to fix.

Noritz tankless water heater code 67, EC67

An AGM (air gas mixer) abnormality. It applies to the NRCP982-DV, NRCP1112-DV, CB180-DV and CB199-DV models.

Cut electrical power to the unit for 20 seconds and restore it once.

Noritz says the AGM may be stuck, and that after power is restored it attempts to recalibrate by rotating through its range. Check that the wiring to the AGM is complete, undamaged and fully seated. A common cause is heavy build-up in the AGM housing.

Noritz tankless water heater code 71, EC71

A gas valve abnormality: the circuit board cannot properly operate the gas valve and solenoids.

Note whether the unit runs from a battery backup, solar inverter or a shared circuit.

Noritz says it is common on newer installations powered by a battery backup or solar inverter that does not produce a pure sine wave, or on a circuit shared with an appliance such as an old refrigerator. Try another outlet on a different circuit; on an existing installation inspect the board for damage and test the voltage to the gas valve and solenoids.

Noritz tankless water heater code 760, EC760

A remote controller transmission abnormality: a communication problem between the unit and the remote control.

Make sure the remote control and cord are securely connected from the unit to the remote.

Noritz's guidance is to check that connection along its full length.

Noritz tankless water heater code 90, EC90

A combustion abnormality: the fuel and air mix is off specification. The unit is either struggling to move air in or out, or cannot reach the set temperature.

Clean the visible intake filter, front cover intake and any intake screen on top of the unit.

Noritz says on a new install the usual causes are low gas pressure, incorrect or poorly installed venting, or dip switches not set for elevation, pipe size or length; on an older install it is most often a dirty unit. Using the maintenance monitors from the remote, the outlet temperature (MM31) should be within 2 degrees of the set temperature and the fan speed (MM49) should read 100; a higher fan-speed number means the unit is struggling to breathe. Internal cleaning and gas work are for a professional.

Noritz tankless water heater code 903, EC903

A combustion abnormality similar to 90, specifically about the unit's ability to pull in combustion air or remove exhaust.

Check the air inlet and the exhaust for blockage or obstruction.

Noritz's checkpoints: the air inlet, the exhaust, and the fan motor for clogged blades, and sudden environmental changes such as a storm. If all are normal, the unit may need a fan-motor adjustment, which needs an external remote control and a call to Noritz customer care.

Noritz tankless water heater code 91, EC91

Incorrect gas type.

Verify the unit is supplied the gas type printed on its rating plate.

Noritz says to verify the correct gas type and that the unit is installed per the installation manual. On an existing installation also have a service representative confirm the manifold gas pressures per the service manual, and clean the fan, burner and heat exchanger fins if there is dust or lint.

Noritz tankless water heater code 92, EC92

The first warning that the built-in condensate neutralizer is near the end of its effective life. It applies to certain condensing models such as the NRC111 and NCC199.

Note the model number against the list in Noritz's article.

Noritz says the neutralizer must be replaced and its timer reset; the replacement part number is SKD7466.

Noritz tankless water heater code C1, C1#

Scale build-up in the heat exchanger on a premix model. The alarm code C1# flashes, where # is 1 to 9. Noritz notes that damage from scale build-up is not covered by the warranty.

Note whether the water is hard and when the heater was last flushed.

Noritz says the heat exchanger must be flushed to clear the code, that the procedure is only for a qualified service professional or authorized Noritz representative, and that unauthorized work may not be covered by the warranty. Contact Noritz America if the code shows.