Georgia homeowner's Rinnai kept throwing code 12, then found the recirculation pump never shut off

After replacing a standard water heater with a Rinnai tankless model, a homeowner in Georgia kept getting an error. The unit ...
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Tankless Water Heater Error Codes: San Diego Plumber Shares Guidance

Rinnai Code 10: Blocked Air Intake Rinnai Code 10 indicates blocked air intake, preventing the proper air-to-fuel mixture necessary for clean combustion. This blockage can occur at the exterior vent ...