Noritz water heater priority light blinking. 20 on display red light on heater blinking. What's wrong?

SOURCE: Noritz tankless water heater not producing hot water

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.

SOURCE: Water Heater Won't Fire up

does the fan come on? this has to happen before it will even try to start if it doesn't your problem goes farther into the unit,, normal pracess if the fan then the ignitor then the flame, It could be in the circuit board most people that have gone with the tankless don't clearly ask the question but that is normal, but if you could clearify the procedure of what it is doing to this point i could be more helpful to you---- e-mail me what is happeing diffrent then what it use to do [email protected]

SOURCE: I have a noritz water tankless heater and hot

Three flashes typically indicates the unit is overheating due to scale. I'd try a descale initially and see if that remedies the problem.

SOURCE: I have a Noritz tankless

you need to recirculate cleaner through the unit for the lime build up.