Bradford White Error Code F4: High Temp Cutoff
How to Fix Bradford White Code F4
- Step 1: Check the water heater's vent for any obstructions (leaves, debris, animal nests). Clear any blockages you can safely reach from the outside.
- Step 2: If you have hard water, consider flushing the tank to remove sediment. Refer to your owner's manual for instructions, or search online for a video specific to your Bradford White model.
- Step 3: Contact a qualified HVAC technician or plumber to diagnose and repair the underlying problem. Do not attempt to reset the high-limit switch yourself.
How to Reset Bradford White Code F4
- 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 F4 Mean?
The F4 error code on your Bradford White water heater indicates that the high temperature limit switch has tripped. This safety device is designed to shut off the gas supply to the burner if the water temperature exceeds a safe level, typically around 190°F (88°C). When this happens, the heater locks out to prevent further operation until the issue is resolved. This is a critical safety feature, and the underlying cause needs to be identified and corrected to prevent potential scalding, damage to the unit, or even a dangerous situation like a steam explosion. Essentially, something is causing the water to overheat. This could be a problem with the thermostat not regulating the burner correctly, a blockage preventing proper water flow, or even a faulty high-limit switch itself. Because this involves gas and high temperatures, it's important to address this issue promptly and safely.
Common Causes
- Faulty thermostat causing excessive burner operation.
- Scale buildup or sediment accumulation in the tank restricting water flow and causing localized overheating.
- Defective high-limit switch tripping prematurely.
- Gas valve malfunction leading to uncontrolled gas flow.
- Improper venting causing flue gas recirculation and overheating.
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| High-limit switch tripped (F4 error displayed) | Continuity across the high-limit switch terminals | Open circuit (no continuity) |
| High-limit switch is open | Resistance of the thermostat sensor | Value within the manufacturer's specified range at the measured water temperature. Refer to the service manual for the temperature/resistance chart. |
| Thermostat sensor resistance is out of range | Voltage to the gas valve during a call for heat | Correct voltage as specified by the manufacturer (typically 24V AC) |
| Water temperature exceeds setpoint | Gas valve operation | Gas valve should modulate or shut off when the setpoint is reached. |
Applicable Bradford White Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| High Limit Switch | — | — | — |
| Thermostat | — | — | — |
| Gas Valve | — | — | — |
Related Codes on Same Models
Other codes that affect the same Bradford White model families as F4.
| Code | Description | Severity |
|---|---|---|
| F1 | Sensor Fault | Warning |
| F10 | Thermistor Short | Warning |
| F11 | Thermistor Open | Warning |
| F13 | Ignition Failure | Critical |
| F14 | Flame Failure | Critical |
| F16 | Blower Failure | Warning |
| F2 | Dry Fire Protection | Warning |
| F6 | Flammable Vapor Lockout | Critical |