HVACopediaRinnai · Tankless water heater
61 Combustion fan motor fault
What the control is telling you
The combustion fan motor is not operating correctly, due to wiring, a seized or obstructed blower, open windings, incorrect supply voltage or a control board fault.
Applies to: SENSEI Series, SENSEI RX/CX Series, Non-SENSEI Series
Likely causes
- Loose, broken or damaged fan motor wiring
- Blower wheel binding or debris in the fan housing
- Check valve behind the fan stuck closed (SENSEI / SENSEI RX/CX)
- Open fan motor windings
- Incorrect fan supply voltage from the PC board
- Faulty PC board
Test and repair steps
- Warning: Turn off power and gas before servicing the fan. Never plug or unplug the motor with power applied; doing so can damage the fan motor and other parts.
- Inspect the harness from the fan motor to the PC board for loose, broken or damaged connections.
- With power and gas off, remove the fan motor and confirm the blower wheel spins freely.
- Check the fan housing for debris that could stop the wheel from turning.
- SENSEI / SENSEI RX/CX Make sure the check valve behind the fan motor is not stuck closed.
- Measure fan motor winding resistance against the Technical Data Sheet (behind the front cover) or service manual; replace the motor if windings are open.
- SENSEI RX/CX With the unit running, measure at CN7: red #1–black #2 = 7-48 VDC; white #4–black #2 = 2-14 VDC; yellow #3–black #2 = 11-13 VDC (see Electric Circuit Table/wiring diagram).
- If windings and voltage are within spec and the fan turns freely, replace the PC board.
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
- RX supply connection sizes · SENSEI RX/CX
- RX water quality limits · SENSEI RX/CX
- RX water treatment and flushing by hardness · SENSEI RX/CX
- RX clearances to combustibles · SENSEI RX/CX
Models that show this code
89 models in Non-SENSEI, RH180 hybrid, SENSEI RX/CX, SENSEI
Other codes on the same units
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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.52. Summarized in our own words; check the original manual for your model.
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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.