Noritz water heater error code 99

Remove the bird's nest in the flue.

The 10, 59, 90 and 99 error codes indicate that a Noritz heater has experienced a combustion abnormality. In most cases, it is the result of an obstruction in the heater's flue. Examine the flue to see if it is blocked by debris and clean if necessary.

How To Resolve The Seven Most Common Noritz Tankless ...

Noritz https://www.noritz.com > Blog
Nov 16, 2015 - This error code involves a breakdown in communication between two tankless water heaters using the Quick Connect Cord. It can occur when more ...

Troubleshooting Noritz Tankless Water Heaters and Error Codes

home-water-heater.com https://www.home-water-heater.com > noritz-error-co...
Error code 90 and 99 ... Action: Check for the obstructed venting, improper gas burning (flame shape and color change). Ensure the water heater gets the ...

Error Codes for a Noritz Water Heater - Waterheatertimer.org

..

Error Code 20 on a Noritz tankless water heater (model EZ98DV) is typically associated with an issue with the "priority" function, which is a feature that allows the water heater to prioritize certain uses of hot water over others.
When the "priority" light is flashing and error code 20 is displayed, it typically means that there is a problem with the priority function and it needs to be reset.
To fix this issue, you can try the following steps:

1. Turn off the power to the water heater by turning off the circuit breaker or removing the fuse.
2. Wait for about 10 seconds and then turn the power back on.
3. Press and hold the "priority" button for about 5 seconds, until the "priority" light turns off.
4. Turn the water heater back on and check to see if the error code has cleared and the "priority" light is no longer flashing.

If the error code 20 still appears and the priority light is flashing, it's best to consult the manual or a professional technician to diagnose the problem.
It's important to note that the error code 20 can also be caused by other issues such as, faulty thermistor, faulty thermistor harness, faulty PCB, etc. So, it's best to get it checked by a professional.

I am having the same error code. Did you ever get an answer?

EC 71 usually means you are using a battery backup that doesn't produce a pure sine wave. OR you recently had a power outage and it shorted the circuit board. if you have a battery backup try unplugging that and see if it works okay. If not, just call Noritz for a replacement c/b.

There are many reasons a tankless heater will stop heating water. The first thing I would look for is a flashing red light on the burner indicator. The flash break down goes as follows

continuous blinking - typically means ignition failure or the unit is overheating; look for visible water inside the unit, have your gas pressure checked, or check the flame rod/igniter for buildup of debris

three blinks - typically indicates 16 error code; typically resolved by performing a descale

4 or 5 blinks - exotic error codes; for these you should definitely contact Noritz tech support

If there is no flashing light, first check your filter for debris. If the filter is clean, your flow sensor is probably stuck. Again I'd recommend contacting Noritz tech support to help you clean the flow sensor.

F76 is a communication error between two quick connected heaters. To clear the code, disconnect power from both heaters, wait 20 seconds, then reconnect power.

you probably had debris get into the filter or flow sensor when the water was turned back on. I'd recommend checking the filter first and if that doesn't work, call Noritz Tech support to help you with the flow sensor.

the filter is a black plug located on the cold water line (labeled cold on the bottom of the unit). It points torwards the left.

You have a 16 error code, abnormal output temperature. I recommend performing a descale to remove hard water deposits in the heat exchanger. This should resolve your issue.

I called Noritz error code 16 is a overheat problem. Noritz say's to flush your coil with vinegar or CLR.
Use a small pump to recirculate the CLR or vinegar through the system for 45 minutes and flush with fresh water. This worked for me.