Rinnai RH180 Hybrid error codes
The RH180 is not a tankless heater. It is a hybrid: a Rinnai tankless engine bolted to a small storage tank with its own circulation pump, sold as a tank replacement that behaves like a tankless unit. That layout is why it needs its own code table, and why reading a Rinnai code chart written for tankless models will mislead you here. Three numbers matter most. Code 38 is a carbon monoxide sensor on this appliance and an exhaust gas temperature sensor on every other Rinnai — if your display reads 38, stop and call a professional. Codes 07 and 63 are both circulation flow faults at two different thresholds, 2.1 GPM and 1.3 GPM, which no tankless Rinnai has. And there is no SS or LC scale warning in this table at all. Every entry below comes from the RH180's own Operation and Installation Manual, not from Rinnai's general diagnostic document.
Not your models? Check the model-number decoder before you read the table below — the code numbers repeat across series and the meanings do not.
| Code | Error | Verdict |
|---|---|---|
| 05 | Air screen restricted | DIY fix |
| 07 | Circulation flow below 2.1 GPM | DIY fix |
| 10 | Air supply or exhaust blockage | Call a pro |
| 11 | No ignition | Call a pro |
| 12 | No flame | Call a pro |
| 13 | Combustion fault | Call a pro |
| 14 | Thermal fuse triggered | Call a pro |
| 16 | Over temperature warning | Call a pro |
| 30 | Flammable vapour sensor fault | Call a pro |
| 31 | Burner sensor fault | Call a pro |
| 32 | Heat exchanger outgoing temperature sensor fault | Call a pro |
| 35 | Tank temperature sensor fault | Call a pro |
| 38 | Carbon monoxide or flammable vapour sensor fault | Call a pro |
| 52 | Modulating solenoid valve signal fault | Call a pro |
| 61 | Combustion fan fault | Call a pro |
| 63 | Circulation flow below 1.3 GPM | DIY fix |
| 71 | Solenoid valve circuit fault | Call a pro |
| 72 | Flame sensing device fault | Call a pro |
| 73 | Burner sensor circuit fault | Call a pro |
| FE | Flammable vapours detected | Emergency — stop |
Every entry above is transcribed from the manufacturer's diagnostic documentation for this exact series, with the source cited on each code page.
Other Rinnai series
Different series, different code table — if your unit isn't a RH180 Hybrid, check yours: