My noritz n-069m is blinking code 90

SOURCE: My Noritz 6.9 flashes a 90 code. I was told by

I recently started getting an error 90 on my N69-M unit. I finally got a hold of someone at Noritz tech support and they state this error is a general combustion/exhaust/air flow error. Here is what they suggested to look at.
Gas Pressure – The unit has a minimum flow rate for the incoming gas and if the system is gas starved, then you have some sort of obstruction or restriction. If this is a new install and you are getting an error 90, this is likely your problem but if this is an existing install that suddenly started getting this error, unless someone was monkeying around with any values you might have in-line, this probably isn’t your problem.
Air Flow – This is a ventilation issues caused by the build-up of dust, lint, etc that chokes the flow of cool air to the unit and causes the burner to overheat. If your unit runs for a while and then pops an error 90, this is probably your problem. They told me they get a lot of these errors when the unit is installed in close proximity to a clothes dryer, which makes sense. To resolve this, remove the front panel and blow out the intake holes and slots (I tried to shop-vac mine before blowing them out and I was amazed at how much the vacuum didn’t remove). After removing the cover, the first thing you should see is a system board that is covered by a black dust shield. The board is held to the unit by 3 screws (one on the top left and two at the bottom). Remove the screws and let the board dangle by the wires plugged in it. You should now be staring at the fan assembly. They suggested that I either remove the whole unit and clean it out or use compressed air to blow it out. I went with the compressed air route because getting the fan assembly out requires removing and eventually reinstalling 2 relatively small screws way in the back of the unit that you have no real easy way to get to. Blow/clean the fan out and then blow out everything else inside the unit. Reassemble and you are good to go, provided this is your problem.
Exhaust – You might see an error 90 if the exhaust can’t freely flow. Two things can cause an exhaust issue to throw this error. One is that the flapper valve on the outlet of the system sometimes gets stuck closed. This should be easy enough to fix. The other is an obstruction in your exhaust ducting or using too small of a diameter duct to exhaust the unit.
Hope this was somewhat helpful and prevents you from having to wait on hold forever for Noritz support or having to pay someone to fix your problem.

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: Noritz Tankless error code 16

The trick with these hot water heaters is to keep the filter screen clean and flush the system with CLR periodically. Code 11 is ignition error. Is your gas valve turned on?

electronic & computer repair& servicre

• 12061 Answers
• Posted on Apr 17, 2010

SOURCE: Would you recommend this brand or another, with

The thing is with these that if they have been used in a "Hard Water" area, they get clogged up inside with deposits, so as long as it's a real "New" looking, inside and out, well I guess $225 - $250 would be an acceptable price. Find out WHY it is being sold.