Bradford White Error Code F11: Thermistor Open
How to Fix Bradford White Code F11
- Step 1: Check the display for any other error codes that might give more clues.
- Step 2: Reset the water heater by turning off the power at the breaker for 30 seconds, then turn it back on. This might clear a temporary glitch.
- Step 3: If the F11 code reappears after the reset, contact a qualified HVAC technician to diagnose and repair the problem.
How to Reset Bradford White Code F11
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Bradford White Error Code F11 Mean?
The F11 error code on your Bradford White tankless water heater indicates that the unit's control board isn't receiving a signal from one of its thermistors. Thermistors are temperature sensors that monitor the water temperature at various points within the unit. An 'open' circuit means the electrical connection between the thermistor and the control board is broken, like a cut wire. Because the control board can't read the temperature, it shuts down the heater as a safety measure to prevent overheating or other potential issues. This error prevents the unit from operating until the problem is resolved. Essentially, the water heater's brain (the control board) can't 'see' the temperature it needs to, so it's playing it safe by not allowing the unit to fire up. This could be due to a faulty sensor, a wiring problem, or even a problem with the control board itself.
Common Causes
- Faulty thermistor (sensor has failed internally)
- Loose or corroded wiring connections at the thermistor or control board
- Damaged wiring harness between the thermistor and the control board (rodent damage, cuts)
- Control board failure (less common, but possible if the board isn't reading the sensor signal correctly)
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Unit displays F11 error | Measure resistance across the thermistor terminals at the control board with the power OFF. Disconnect the thermistor wires from the board first. | A specific resistance value depending on the water temperature. Consult the service manual for the thermistor resistance chart. |
| Thermistor resistance is outside the expected range or reads infinite (open circuit) | Inspect the wiring harness and connectors between the thermistor and the control board for damage or corrosion. | Wiring and connectors should be clean and intact. |
| Wiring appears OK | Check the voltage at the control board thermistor connection with the unit powered on (low voltage DC). | A stable DC voltage, typically 5VDC, should be present. |
| Voltage is present at the board but resistance is bad | Replace the thermistor. | New thermistor resolves the F11 error. |
Applicable Bradford White Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Thermistor | — | — | — |
| Wiring harness | — | — | — |
| Control board | — | — | — |
Related Codes on Same Models
Other codes that affect the same Bradford White model families as F11.
| Code | Description | Severity |
|---|---|---|
| F1 | Sensor Fault | Warning |
| F10 | Thermistor Short | Warning |
| F13 | Ignition Failure | Critical |
| F14 | Flame Failure | Critical |
| F16 | Blower Failure | Warning |
| F2 | Dry Fire Protection | Warning |
| F4 | High Temp Cutoff | Critical |
| F6 | Flammable Vapor Lockout | Critical |