Rinnai RC98HP not producing enough hot water

JZZH

Hi, the problem started about a month ago. There is hot water, but it is very obvious that it is not hot enough.
No error code. I had de-scaled half a year ago, and I don't see any dust build up after removing the cover. The cold water inlet filter is also clean.
When I look into the observation hole, I can see blue flame on left side, but the right side is dark. I am not sure if it is expected to have flame on both sides, so I took a video: https://drive.google.com/file/d/1n5y5LT6lJHibf_70MHM2RFZfSEPE_NqD/view?usp=sharing. You can see that when I move to the left side of the hole (which would give view of flame on the right side - if it is expected to have flame on the right side), I don't see flame.
Please advise if that is normal or what the problem is. It does not report any error code.

rick in Alaska

You might take the impellor out and clean it. Sounds like maybe it isn't reading flow right and not allowing high fire. I am not familiar with that model, but you should be able to look it up to see how to get to it.
Rick

JZZH

Thank you, Rick.
I looked this up: https://www.youtube.com/watch?v=8gLRNEKqFDA&ab_channel=ThatTanklessGuy. Will study it and the Rinnai manual further and give it a try.