We live in a house that we built new two years ago and have a pair of Rheem RTG-53PVN tankless water heaters installed that we have had no problems and the water comes out as hot as the day we got the units. A week ago, we got two codes displaying on the separate LCD display. The first is 1L. I looked in the Rheem User & Care Manual and it says 1L - Water heater has buildup of lime deposits - Contact a dealer for service. The other code I get is 2. There is no information or description for it in the manual or anywhere I searched online.
In order it shows them 2 and then 1L is second and then back to the temperature display.
I'll say up front that I have not done annual maintenance on them up till now. After reading the manual step by step I removed the water filters on each unit. Both of them had build up on them. I cleaned them with CLR and put them back in and turned on the gas/water etc and the system is back up and running but the codes have not gone away.
Any thoughts or suggestions or do you think my tanks may have to much build up in them and I'll have to call someone out to the house?