Rinnai code 14: Overheat safety device tripped
Continuous flow hot water system (Australia), tankless water heater (United States)
The thermal fuse or overheat switch tripped because the heat exchanger got too hot. The heater runs, then stops.
This needs a licensed gas technician. There is nothing safe to check yourself. Leave the covers on and book a professional.
This involves the gas supply or burner. Only a licensed technician should open the unit or work on gas parts.
What causes it
Australian models
-
Scale build-up inside the heat exchanger is causing hot spots.
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The gas type or combustion settings are wrong for the gas supply.
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The thermal fuse or overheat switch itself has failed.
US models
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Scale build-up in the heat exchanger. Flushing is needed, and hard water should be treated.
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Wrong gas type, gas venturi or parameter settings, or a gas valve DIP switch on the control board left ON (the single switch on SENSEI models; switch 5 of SW2 on VC and KB models).
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A cracked or damaged heat exchanger, blocked fins, or a faulty overheat sensor or control board.
How to read this code on your unit
Booking a licensed gas technician
Have the heat exchanger flushed and descaledplumber
- Scale from hard water builds up inside the heat exchanger and restricts flow and heat transfer.
- Book a licensed plumber or the manufacturer's service agent to flush and descale the heat exchanger using the manufacturer's flushing procedure.
- Ask about water treatment if you have hard water, so the scale does not come back.
Book a licensed gas technicianlicensed gas technician
- Turn the unit off and leave the covers on. Gas components must only be serviced by a licensed technician.
- Note the code, how often it appears, and the model and serial numbers from the rating label.
- Book a licensed gas technician and give them those details.
Models that show this code
73 models in 15 ranges
| Range | Models |
|---|---|
| Heavy Duty (commercial) | REU-AM3237WC (HD32e), REU-VCM2837FFC (HD28i), REU-VCM2837WC (HD28e), REU-NB3237WC-AK (Heavy Duty 32C), REU-NB3237FFC-AK, REU-NB3237WC-50-AK, REU-NB3237FFC-50-AK |
| Infinity | REU-AM3237W (Infinity 32), REU-AM2626WDL (Infinity 26 Touch), REU-AM2626WD (Infinity 26), REU-AM2024WD (Infinity 20), REU-AM1620WD (Infinity 16), REU-AM1220WD (Infinity 12), REU-A2626WB (B26), REU-A2024WB (B20), REU-A1620WB (B16) |
| Infinity B | REU-BM2626W (Infinity B26), REU-BM2024W (Infinity B20), REU-BM1620W (Infinity B16), REU-BM1220W (Infinity B12) |
| Infinity Enviro | REU-E2626W (Infinity Enviro 26), REU-E1620W (Infinity Enviro 16), REU-NB3237W-AK (Infinity Enviro 32), REU-NB3237W-50-AK |
| Infinity internal | REU-VCM2837FF (Infinity 28i) |
| Commercial (KB) | C199i (REU-KBD3237FFUDC-US), C199e (REU-KB3237WDC-US) |
| KB | RU80i (REU-KB2530FFUD-US), RU80e (REU-KB2530WD-US), RU90e (REU-KBD2934WD-US), RU98i (REU-KB3237FFUD-US), RU98e (REU-KB3237WD-US) |
| KBD | RUC80i (REU-KBD2530FFUD-US), RUC90i (REU-KBD2934FFUD-US), RUC98i (REU-KBD3237FFUD-US) |
| KBP | RUR98i (REU-KBP3237FFUD-US), RUR98e (REU-KBP3237WD-US) |
| KCM | RUCS65i (REU-KCM2025FFU-US), RUCS75i (REU-KCM2528FFU-US), RUS65e (REU-KCM2025W-US), RUS75e (REU-KCM2528W-US) |
| Luxury (VC) | RL75i (REU-VC2528FFUD-US), RL75i(A) (REU-VC2528FFUD-US(A)), RL75e (REU-VC2528WD-US), RL75e(A) (REU-VC2528WD-US(A)), RL94i (REU-VC2837FFUD-US), RLX94i (REU-VC2737FFUD-US), RL94e (REU-VC2837WD-US) |
| SENSEI commercial | CU199i (REU-N3237FFC-US), CU160i (REU-N2530FFC-US), CU199e (REU-N3237WC-US), CU160e (REU-N2530WC-US) |
| SENSEI residential | RU199i (REU-N3237FF-US), RU180i (REU-N2934FF-US), RU160i (REU-N2530FF-US), RU130i (REU-N2024FF-US), RU199e (REU-N3237W-US), RU180e (REU-N2934W-US), RU160e (REU-N2530W-US), RU130e (REU-N2024W-US) |
| SENSEI residential with pump | RUR199i (REU-NP3237FF-US), RUR160i (REU-NP2530FF-US), RUR199e (REU-NP3237W-US), RUR160e (REU-NP2530W-US) |
| Value (VC) | V53e (REU-VAM1620W-US), V53De (REU-AM1620WD-US), V65i (REU-VC2025FFU-US), V65e (REU-VC2025W-US), V75i (REU-VC2528FFU-US), V75e (REU-VC2528W-US), V94i (REU-VC2837FFU-US), V94Xi (REU-VC2737FFU-US), V94e (REU-VC2837W-US) |
Where this comes from
- Error codes for gas continuous flow water heaters (HW Gas CF ERR) , page 2
- Infinity gas continuous flow operation and installation manual , page 12
- Infinity Enviro 32 / HDC32 operation and installation manual , page 12
- Troubleshooting tankless water heater diagnostic codes (100000652), non-SENSEI and SENSEI series , page 21, 22, 23
- N Series residential condensing installation and operation manual (100000467), RU199e/RU180e/RU160e/RU130e , page 59
Checked against the manufacturer's manual on 9 October 2026.
Other Rinnai tankless water heater codes
| Code | Meaning | What you can do |
|---|---|---|
| 03 | Power cut during bath fill | You can often fix it |
| 05 | Bypass flow control failure | Safe checks first, then a pro |
| 10 | Air intake, flue or condensate blockage | Safe checks first, then a pro |
| 11 | No ignition | Safe checks first, then a pro |
| 12 | Flame failure or low gas flow | Safe checks first, then a pro |
| 13 | Combustion fault | Safe checks first, then a pro |
| 15 | Venturi control failure | Safe checks first, then a pro |
| 16 | Over-temperature shutdown | Safe checks first, then a pro |
| 17 | Venturi blockage | Safe checks first, then a pro |
| 18 | Gas valve adjustment limit | Call a pro |
| 19 | Electrical earth fault | Call a pro |
| 57 | Burner overheat switch open | Call a pro |
See all overheat codes on tankless water heaters across brands.