Hello, I removed the two metal panels that are visible when looking at the water heater, which is a small one connected to only my unit. It is in the basement of the house. It is about 4 feet tall. Upon removing the metal panels, and the insulation layer, I didn't see any temperature-dial mechanism, nor anything else, that could be used to turn the temperature down, which surprised me, as I've done this for some water heaters in other houses in the past, and it was very easy. The metal panels are near one another - one is a few inches below the other. I looked all around the unit and couldn't see anything else. The temperature is too hot, and I'd like to save on my electric bill. Any suggestions?

Hello, doityourself forums! My tankless heater (RUR-199e, as in the subject header) is about two and a half years old. Thanks to some miscommunication on install, it was running its recirc pump for a lot more than it was supposed to for a big chunk of that. We have very hard water, so any problems I've run into before this have mostly been scale-related--now that the recirc pump runs at a sane schedule and we've had a softener system installed, those issues seem to have calmed down, but I have a new one. About eight weeks ago, I was getting code 11 on demand (the ignition code). The flame rod assembly was highly corroded, so I bought a new one and replaced it (I also went ahead and did a vinegar flush, which I'd been doing about every two months or so while we were dealing with scale issues). About three weeks ago, I got code 11 again, and noticed that there was already some pretty significant corrosion on the all-new flame rod assembly. I sanded some carbon off the rod and igniter and used a scrub pad to clean up around the assembly, and it went back into service. Now, today, I got another code 11 and noticed the entire assembly was, again, deeply corroded. As far as I can tell, there's no infiltration coming from outside the unit--the area around the assembly was relatively dry, but the felt gasket it comes with was soaked, and there appears to be some scale on the inside of the heat exchanger, visible from the assembly mounting point. This tells me that there might be a small leak inside the heat exchanger that is letting some water collect in there. Does this seem like a reasonable diagnosis, or is there some other (cheaper-to-fix) problem that it might be? Another thing I'm noticing is that sometimes, when I turn off the demand, something will rattle somewhere in the unit. I can't tell where, there's too much noise and it's too sporadic, but what it sounds like is a chunk of something that's being held in position while the water is flowing that then settles down somewhere after the water stops. My guess is that it's a big chunk of scale and I just need to run a few flushes to get it out, but are there other things it could be? Thanks in advance! I have bunches of photos to share: [img]https://cimg7.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_170714702_mp_ef6518f40114dba39f63e410c9ba2ee32e216e83.jpg[/img] [i]When I first opened the unit. No visible condensation anywhere, but tons of corrosion. I don't really have any clue what the yellow chunks are.[/i] [img]https://cimg0.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_170817962_352d5fb9b7d7a81be64972db0e77f88e10672b17.jpg[/img] [i]Focus on ground screw[/i] [img]https://cimg2.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_170822907_fb3f633660a8d9c23d1d5786de68025872548368.jpg[/img] [i]Focus on flame rod and the ceramic thing in the middle (a thermistor maybe, for safety cutoff?)[/i] [img]https://cimg0.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_173026054_mp_a2f0c65795bce9f75d7b26624e0febc5ed0953e3.jpg[/img] [i]Notice the buildup inside the exchanger (the little white crystals), seems like scale from evaporating water.[/i] [img]https://cimg7.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_171136782_96cc0dcaa4c9bf6e9915be851c776558a8002070.jpg[/img] [i]Tons of corrosion in the interface between the gasket and the assembly plate.[/i] [img]https://cimg5.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_170934812_bd87740a2bf4ceaf63093240365d89f224dbe5f4.jpg[/img] [i]View of the flame rod and ignition, some carbon build-up, I don't really have a sense for how normal this is for eight weeks of life[/i] [img]https://cimg8.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_170940828_5bf72cf977e32621d058627ab11f78b83c5b1027.jpg[/img] [i]Side view with more consistent background[/i] [img]https://cimg5.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_170945677_3f3f8475d1fa9691b7012735ff5fb2e939bfc3a2.jpg[/img] [i]Back of the removed assembly[/i] [img]https://cimg7.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_170948520_3c0c7418d7710033ff5cb78dd2bafa9a1f590dd0.jpg[/img] [i]Front of the removed assembly[/i] [img]https://cimg3.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pxl_20221203_173618969_mp_6a50f313492529649c8eed8276ea8d225fef096d.jpg[/img] [i]Replacement assembly in place.[/i]