Tip & How-To about Noritz 8.4 Gallon Residential Tankless Water Heater - N-084M

Error Code 90 Solution

Over time after about 5 to 6 years many Noritz heaters tend to display error code 90 and stop working. The unit has to be shut off and back on for it to work again for a short time. Error code 90 is indication of abnormal combustion and can have a few causes, including blockage in the exhaust vent. However the problems lies mostly with the combustion fan. that is the fan that you hear when the unit is running. It is unable to deliver enough air to normal combustion.
Replace the fan and while doing it clean the air pathway with compressed air. In addition remove the ignition and heat senors (all in one assembly, in the middle of the unit) and sand them very slightly with very fine sandpaper (400 or higher) to remove build up on them.
While the fan is being ordered you can at your own risk operate the unit with the cover slightly open (about 2 in.) at the bottom and the unit will run without code 90. It is highly recommended to hire a trained technician for the above work as gas appliances pose a significant danger to human life and property if not installed or maintained properly. This solution is for informational purposes only. Please be safe.
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I have a Noritz tankless water heater (model n-132m). I am getting an error code of 71. What does that mean?


The Noritz Manual shows fixed for the following error codes:
11
21
90
99
For all other codes this is the recommendation:
Contact our sales agent if:
• Any other error code appears.

Sep 12, 2014 | Noritz Commerical Tankless Water Heater...

1 Answer

I have a Nortitz natural gas water heater, model #N-063s-1. Acouple of days ago it stopped heating the water. what can I do myself to fix this matter. Thanks, lynnatheana@hotmail.com


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.

Jul 31, 2010 | Noritz 6.3 Gallon Residential Tankless...

3 Answers

My Noritz 6.9 flashes a 90 code. I was told by Noritz that this code relates to air flow.. and that the unit needs to be cleaned/serviced. Is this something I can do myself? If so, how do I do it? If not whom should I call?


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.

Nov 14, 2009 | Noritz 6.9 Gallon Residential Direct Vent...

1 Answer

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?

Oct 17, 2009 | Noritz 6.9 Gallon Residential Direct Vent...

4 Answers

heater not working


Probably a 12 or 21 code. Neither of which a Consumer can do ANYTHING about. Call Noritz 1-888-382-6568 and they will have a Regional Service/Repair Field Engineer call you and diagnose problem.
This is a sophisticated appliance unserviceable to Consumer but you may diagnose it with the help of the FE for Service Contractor to repair.
N069M-DV was discontinued 3 years ago replaced by N0751M-DV. Have you checked the inlet filter since you bought it? Is it on good soft water? It's a strong pretty dependable unit IF INSTALLED PROPERLY and MAINTAINED.

Mar 02, 2009 | Noritz 6.9 Gallon Residential Direct Vent...

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