Navien 10E - Navien Filter Location And Cleaning to Fix Error 10 or error code 10
Navien Air Filter
Disclaimer: I am not a Navien or HVAC "professional". I would not perform this type of work if you are not comfortable with DIY projects and have a least a little bit of experience fixing things. But this does look pretty simple...
I will describe here what might be done to fix Navien Error 10 subcode 21, or Navien 10E 021.
Well the first thing you always try when you have a problem is a "reboot". I powered the unit off at the power bar then on again. The error remained. FWIW the error I got looked like this:
Looking this code up in the manual reveals it to be "Abnormal Air pressure". Being as it is the middle of summer here and a balmy 84 degrees (27C) and calm, I'm doubtful the air pressure can be that abnormal. As with engines and the like, it usually means air is being restricted, so lets go looking for some type of filter.
First things first: Turn the power off to the unit! You can then remove the front panel (cover plate by removing the four screws - and if you can't figure it out without a picture, you probably shouldn't be doing this at all...). A quick look inside shows that inbound air comes in the left and exhaust out the right. Look for the screw in the pic below. I'll bet this is where the filter is:
If you were to remove this screw, I'll bet it would slide out towards you a bit - but it might be easier to turn it to it's side to remove like the picture below:
The filter may look like the one below - obviously clogged with bug parts, dust, dirt and other refuse:
Now to be fair, I've never cleaned my intake filter. But then again, I never performed the regular maintenance on my old tank water heater either (draining it out once a year to remove the residue at the bottom of the tank). Looking at the krud in the intake filter, I'd guess that I should be doing this more often e.g. at least once a year. Let's see how long it takes to do and if it fixes the problem...
Clean the filter by using a brush. If it were me I might use the "wire tooth brush" as per below:
and then rinse under the tap thoroughly. Then dry it thoroughly.
And to install, just reverse the previous steps - slide it back in place. Replace the screw. Put on the cover plate. Turn on your power. Test... Houston, we have lift off. Error code gone and hot water once gain. Goodbye to Navien Error Code 10. At least for now anyway. I'll monitor and update accordingly if the problem returns in the near future.
Total time for this fix was about 15 minutes. Now that I've done it I could do it in five minutes I would think.
I'll call this a minor problem because it was an easy fix and probably something that should be done once a year or so anyway as general unit maintenance.