HVACopediaRinnai · Tankless water heater
S Venturi reset sequence: step S (SENSEI)
What the display is showing
A screen shown on SENSEI (non RX/CX) units while stepping through the venturi/gas valve reset procedure by pressing button B on the PC board for 1 second at a time. It comes after F and before E.
Applies to: Rinnai SENSEI tankless (RU, RUR, RSC, CU)
What to do
- Press B for 1 second from the F screen to reach S, then press B again for E.
Settings for these units
RSC supply connection sizes · SENSEI
| Connection | Size |
|---|---|
| Gas | 3/4 in. NPT |
| Cold inlet | 3/4 in. NPT |
| Hot outlet | 3/4 in. NPT |
| Condensate drain | 1/2 in. NPT |
| Pressure relief valve | M33 thread |
The PRV and its adapter come in the box; PRV must be rated 150 psi and at least the heater Btu/h.
Condensate drain line must stay at least 1/2 in. over its whole length.
RSC water quality limits · SENSEI
| Contaminant | Maximum level |
|---|---|
| Total hardness | Up to 200 mg/L |
| Aluminum | Up to 0.2 mg/L |
| Chlorides | Up to 250 mg/L |
| Copper | Up to 1.0 mg/L |
| Dissolved CO2 | Up to 15.0 mg/L |
| Iron | Up to 0.3 mg/L |
| Manganese | Up to 0.05 mg/L |
| pH | 6.5 to 8.5 |
| TDS | Up to 500 mg/L |
| Zinc | Up to 5 mg/L |
Damage from water above these limits is not covered by warranty.
Hard water should be treated; use the Service Soon (SS) reminder (parameter 03) for flushing intervals.
- RSC clearances to combustibles · SENSEI
- RSC temperature settings available · SENSEI
- Water quality limits - RU/RUR/CU · SENSEI
- Clearances - RU/RUR/CU · SENSEI
Models that show this code
20 models in SENSEI
Other codes on the same units
- Mute Controller key beeps on/off
- Parameter mode Parameter settings menu
- Perf data Performance data viewer (live readings and counters)
- Priority light Priority light on (this controller is in charge)
- SE Cascade diagnostic display (error on secondary unit)
- SS Service Soon alert (also listed as 55)
- t Venturi reset sequence: step t
- °C/°F Temperature scale switch (Celsius / Fahrenheit)
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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), Code 17 and Code 52 reset procedure p.28-29. Summarized in our own words; check the original manual for your model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.