Yes, this happens just about every WINTER on ours. The bummer of the exhaust on our goes from the Top of the Noritz tankless water heater straight to the roof outside. The 3 inch exhaust PVC Pipe with Filter doesn't terminate at the top of the water heat like yours does, but the 3 " Nortiz Exhaust pipe goes directly from the top of the Noritz water heater housing, through the attic to the roof outside. That's a problem in the winter because ice can build up on the bird and critter protection screens connected to the Noritz 3" PVC exhaust and causes Ice Blockage, which in turn restricts the flow of the exhaust, that decreases the proper air/oxygen flow needed to combust with the gas in the Noritz Tankless heater. Very much like restricting the air flow to fuel injectors on your car's engine. Or like the old cars that had Carburetors. It's basically a problem with Fuel/Air mixture, restricting air flow means your Noritz is running "Lean" of air, not enough oxygen to combust with the fuel. A little bit like in your fireplace, if you shut off the air to the fireplace from you control valves, the fire goes down to a very slow burn, not providing enough heat. But in you Noritz, it's much more precisely controlled and need an exact flow of air, hence, it shuts itself down, hence the code error. These are very easy fixes, but not accomplished very often, Hence forgotten to Do. Best to make a little sign and stick these To Do's when you get a Nortiz Error 90 on that little lite almond colored Noritz Monitor box.
@@rlpring78 whoa really?? I would check the output air vent then. It may have blockages. If that's clear, you could also try opening up the combustion chamber and blow it out with compressed air.
Another check I do on ours is the small water supply screen filter located above the blue valve shut off lever, just above the blue lever, tucked up close to the bottom of the Noritz bottom case, (you have to bend down and look up at the bottom of the case to see where the filter is) under the Noritz water heater. Careful to first turn the blue colored valve lever cold water supply to the off position. Large cup or small bucket to catch water underneath, Put rag around hashed larger of the conjoined two brass covers to prevent gouging to the threaded brass cover, (I use channel lock pliers to unscrew, catching the water, SLOWLY unscrew brass threaded cover, make note of the way the parts come out and put in exactly as they came out later, Note it has a some spring load on it from the spring inside and the screen filter is at the end of the filter assembly, that catches small bits of calcium and debris deposits that is coming from your cold water supply, to keep the Noritz clear and clean within the system. Put all parts securely in a container, take a soft brush under a closed drain sink and flush out the debris from the screen filter, reinstall the same way it came out, that you carefully made note of earlier. I do this once a year. Sometime more debris than other years is on this filter screen.
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I want to thank you! I didn’t even know there was a filter outside it worked😊
You rock! Thanks so much for posting and saving me many hours of troubleshooting!!
Just did this and it worked! Thanks for this video, really saved us some money.
Dude, I wish I could add more than 1 'Like' ! Super easy and helpful.
Yes, this happens just about every WINTER on ours. The bummer of the exhaust on our goes from the Top of the Noritz tankless water heater straight to the roof outside. The 3 inch exhaust PVC Pipe with Filter doesn't terminate at the top of the water heat like yours does, but the 3 " Nortiz Exhaust pipe goes directly from the top of the Noritz water heater housing, through the attic to the roof outside. That's a problem in the winter because ice can build up on the bird and critter protection screens connected to the Noritz 3" PVC exhaust and causes Ice Blockage, which in turn restricts the flow of the exhaust, that decreases the proper air/oxygen flow needed to combust with the gas in the Noritz Tankless heater. Very much like restricting the air flow to fuel injectors on your car's engine. Or like the old cars that had Carburetors. It's basically a problem with Fuel/Air mixture, restricting air flow means your Noritz is running "Lean" of air, not enough oxygen to combust with the fuel. A little bit like in your fireplace, if you shut off the air to the fireplace from you control valves, the fire goes down to a very slow burn, not providing enough heat. But in you Noritz, it's much more precisely controlled and need an exact flow of air, hence, it shuts itself down, hence the code error. These are very easy fixes, but not accomplished very often, Hence forgotten to Do. Best to make a little sign and stick these To Do's when you get a Nortiz Error 90 on that little lite almond colored Noritz Monitor box.
I have the NRC 98 Model and the filter is showing different.
Thanks for the tip.....
Mine doesn’t have an air filter. Any other suggestions?
@@rlpring78 whoa really?? I would check the output air vent then. It may have blockages. If that's clear, you could also try opening up the combustion chamber and blow it out with compressed air.
I dnt see a air filter on mine 😢
Different models shows differently
Another check I do on ours is the small water supply screen filter located above the blue valve shut off lever, just above the blue lever, tucked up close to the bottom of the Noritz bottom case, (you have to bend down and look up at the bottom of the case to see where the filter is) under the Noritz water heater. Careful to first turn the blue colored valve lever cold water supply to the off position. Large cup or small bucket to catch water underneath, Put rag around hashed larger of the conjoined two brass covers to prevent gouging to the threaded brass cover, (I use channel lock pliers to unscrew, catching the water, SLOWLY unscrew brass threaded cover, make note of the way the parts come out and put in exactly as they came out later, Note it has a some spring load on it from the spring inside and the screen filter is at the end of the filter assembly, that catches small bits of calcium and debris deposits that is coming from your cold water supply, to keep the Noritz clear and clean within the system. Put all parts securely in a container, take a soft brush under a closed drain sink and flush out the debris from the screen filter, reinstall the same way it came out, that you carefully made note of earlier. I do this once a year. Sometime more debris than other years is on this filter screen.