Rinnai code SE: Cascade connection failure
Continuous flow hot water system (Australia), tankless water heater (United States)
On commercial installations with several linked (cascaded) heaters, the primary unit shows this when one of the secondary units has an error.
This needs a licensed gas technician. There is nothing safe to check yourself. Leave the covers on and book a professional.
Only some models show this code. Check the list below.
What causes it
Australian models
-
A secondary heater in the cascade has its own error code. Check that unit's display.
US models
-
One of the secondary heaters in the cascade has its own error code. Check that unit's display.
How to read this code on your unit
Booking a licensed gas technician
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
29 models in 6 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) |
| SENSEI commercial | CU199i (REU-N3237FFC-US), CU160i (REU-N2530FFC-US), CU199e (REU-N3237WC-US), CU160e (REU-N2530WC-US) |
Where this comes from
- Error codes for gas continuous flow water heaters (HW Gas CF ERR) , page 6
- 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 57
Checked against the manufacturer's manual on 9 October 2026.
Other Rinnai tankless water heater codes
| Code | Meaning | What you can do |
|---|---|---|
| 58 | Secondary heat exchanger overheat | Call a pro |
| 61 | Combustion fan failure | Call a pro |
| 63 | Recirculation low flow | Call a pro |
| 65 | Water flow control failure | Safe checks first, then a pro |
| 66 | Bypass flow control fault | Call a pro |
| 70 | Control board (PCB) failure | Safe checks first, then a pro |
| 71 | Gas solenoid valve failure | Call a pro |
| 72 | Flame rod circuit error | Call a pro |
| 73 | Burner thermocouple fault | Call a pro |
| 79 | Water leak detected | Safe checks first, then a pro |
| 92 | Neutraliser end of life | Call a pro |
| LC | Scale build-up in the heat exchanger | Safe checks first, then a pro |