Noritz f 76 error blinking f 76 and on off light blinking at the same time. Everything works fine turned on and off hot h20 it goes to burner on 120 and then goes back to blinking f 76 after burner turns off.

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.

MAke sure your flu is not making any 90degree turns. Use 45degree turns only. Error 99 is a combustion error. Usually referring to a blocked/obstructed flu. That said, a flu wit a lot of 90degree turns can act like restrictions to tankless heaters. If the flu i straight and clear, then you have a burner problem. Somethign you want Noritz to deal with.

error code 123 is a flame rod sensor problem. Chances are the flame rod is sending a weak signal to the control unit. Check for a loose flame rod electrical connector. Peek in the flame inspection windows to ensure there is a proper flame on that side of the burner. If non of the above then try removing the flame rod and cleaning with 400 grit sandpaper or replace it with part order # SKC7448 (called an Ignition plug ELV & Packing EHK SETV)

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.

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.

Here are a couple things to look for:

1) flashing burner light - a flashing burner light indicates the unit is getting an error code
common error codes:
A. continuous flashing - ignition failure or abnormal combustion; look for visible water in the machine indicating a leak, check gas pressure, debris or buildup on flame rod/igniter plug, or clean unit with compressed air
B. 3 flashes - error 16, abnormal outlet water temperature; typically this code indicates you'll need to descale you unit
C. 4 or 5 flashes - exotic error codes; you should contact Noritz technical support to deal with these codes

2. If there is no flashing code, try increasing the hot water flow. In the summer time you typically use less hot water; this can result in intermittent operation of your tankless heater. Increase water flow by either: A. cleaning your showerhead and removing scale deposits B. widening your flow restrictor C. Remove your flow restrictor in the showerhead

3.If none of these resolves your problem, you probably have debris in your flow sensor. Contact Noritz technical support for a walkthrough on removing debris from a flow sensor.

what the error code on the unit? if you hold the up and down arrow keys and scroll to the number 90-99 it will give you the codes, or call nortiz and they will walk you through the diagnostics

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.

How many faucets do you have on when this happens? Turn on more than 1 and if it still does the samt thing than I would check to see if the inlet water screen has debris in it. Valve off the unit and look at the inlet water side and theres a screeen that you should be able to remove and clean undeneith some running water and then replace. Good Luck

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.