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RUC90i rinnai goes cold when trying to run a bath.

Hi, We just had a Rinnai RUC90i installed a few months ago, licensed plumber did it. works fine with dishes, but sometimes has a tendency to go cold after 5 or 10 minutes in the shower, and always goes cold when running a bath. Any suggestions??


  • Jack
    Jack Member Posts: 1,047
    Look at your manual and figure out how to pull up the error codes on the touch pad. It will store 10 error codes in descending order. If the unit faults out it will show the code. If you turn off the water, it stores it but it is no longer shown on the control. I suspect and error code 25 or 12. The 25 would indicate a condensate drain problem. My first thought however, is that your gas line is undersized when the unit is seeing high flows and if the right amount of gas isn't provided the unit is faulting out.