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Rinnai Tankless Water Heater Issues

mekristy Member Posts: 1
edited April 5 in THE MAIN WALL
Previous homeowner was the one who had a Rinnai REU-V2520FFU-US installed. I wasn't aware until a month ago that it came with a controller which should have been installed. Bought the house 3 years ago with no controller installed or left behind. Only 1 shower got hot water initially but not that hot. Everything else in the house (minus maybe the washing machine?) got cold water. I bought the mc-601-bk controller since I was told it replaced the mc-91-2-us controller. I don't know how to 100% sync it to the tankless water heater even after finding a manual online. After reading the manual, it's saying a max of 4 controllers could be installed but more than the single master controller is optional. I don't THINK I have warranty on my tankless water heater either. (Serial # 05.06-120823) Rinnai takes a while (2 weeks min) to respond. So I’m wondering if a technician installs the controller, would that controller most likely fix my issue? Should I be going about this a different way?
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