HVACopediaRinnai · Tankless water heater
22 Gas valve adjustment fault
What the control is telling you
Fault with gas valve adjustment, typically linked to the front reed switch position or incorrect gas valve parameters.
Applies to: SENSEI RX/CX Series
Likely causes
- Reed switch on front of gas valve not positioned correctly
- Incorrect gas valve parameters
Test and repair steps
- Confirm the reed switch on the front of the gas valve is seated in its correct location.
- Check all gas valve parameters; if any are wrong, re-enter them per the Gas Valve Replacement Instructions (100000855).
Settings for these units
RX supply connection sizes · SENSEI RX/CX
| Connection | Size |
|---|---|
| Gas | 3/4 in. MNPT |
| Cold inlet | 3/4 in. MNPT |
| Hot outlet | 3/4 in. MNPT |
| Condensate drain | 1/2 in. MNPT |
Vent connection: 2 in. nominal PVC/CPVC/PP or 3 in./5 in. concentric.
Full specs (input, flow, weight) are only on each model's spec sheet, not in this manual.
RX water quality limits · SENSEI RX/CX
| 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 |
Water damage beyond these limits is not covered by warranty.
- RX water treatment and flushing by hardness · SENSEI RX/CX
- RX clearances to combustibles · SENSEI RX/CX
- RX temperature settings available · SENSEI RX/CX
Models that show this code
10 models in SENSEI RX/CX
Other codes on the same units
- 16 Outlet water over-temperature safety shutdown
- 17 Venturi blockage
- 18 Gas valve air/fuel adjustment limit reached
- 19 Electrical grounding / DC circuit short
- 21 PC board data transfer error
- 25 Condensate pump failure or clogged drain
- 32 Outlet water temperature thermistor fault
- 33 Heat exchanger thermistor fault
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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.33. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
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.