Unit shuts down with error code 14; may occur after extended operation or at high temperature setpoints.

Safety first: Turn OFF power and gas. Allow the heater to cool for at least 30 minutes before touching internal components.

Steps to check and correct:

• Check for scale buildup: If the unit has not been descaled in the last 12 months (or more often in hard water areas), perform a full descaling procedure using a pump, hoses, and white vinegar or approved descaling solution through the Noritz service valves. Follow the Noritz service manual for your model.
• Verify water flow: Ensure inlet water filter screen (at the cold water inlet) is clean. Shut off water, remove the filter, rinse debris, and reinstall. Confirm that all hot water shutoff valves are fully open.
• Inspect overheat sensors: Locate the overheat sensors/thermistors on the heat exchanger. Check wiring connections for looseness or damage. Do not bypass sensors. Replace any sensor that appears damaged or tests out of specification.
• Check for restricted exhaust: A partially blocked vent can cause excessive heat. Inspect venting per the steps in error 10 and correct any issues.
• Reset and test: After descaling and checks, restore power and gas. If error 14 persists, the thermal fuse or hi-limit assembly may have opened and will need replacement by a qualified technician.