Thermeau
Thermeau Pool Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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F01
Heater will not start; display shows F01 shortly after a call for heat.
Water Flow Fault / Insufficient Water Flow
F02
Heater attempts to start but shuts down with F02; fan may run briefly then stop.
Air Flow Fault / Fan or Pressure Switch Error
F03
Heater locks out with F03; unit may start then quickly shut down without heating water.
Ignition Failure / No Flame Detected
F04
Heater starts but shuts down with F04; may light briefly then extinguish.
Flame Loss / Unstable Flame
F05
Display shows F05 and heater will not fire; may occur immediately on startup.
High Limit Switch Open / Overheat Protection
F06
Heater displays F06 and will not operate; may occur intermittently.
Outlet Water Temperature Sensor Fault
F07
Heater shows F07 and shuts down; may occur during operation as water warms.
Inlet Water Temperature Sensor Fault
F08
Display shows F08; heater will not respond to thermostat changes.
Water Temperature Sensor Mismatch / Calibration Error
F09
Heater displays F09 and will not ignite; may click but no flame appears.
Gas Valve or Gas Supply Fault
F10
Heater shows F10 and shuts down; may occur randomly during operation.
Flame Sensor Circuit Fault
F11
Display shows F11; heater may not respond to keypad inputs or may behave erratically.
User Interface / Keypad Communication Error
F12
Heater shows F12 and will not start; may occur after a power surge or lightning event.
Control Board Internal Fault
F13
Heater displays F13; unit may start but shuts down quickly without heating.
Exhaust Temperature Overlimit / Flue Sensor Fault
F14
Heater shows F14 and refuses to start; may be accompanied by fan not running.
Fan Speed / RPM Feedback Fault
F15
Display shows F15; heater may start but then shuts down with no obvious mechanical issue.
External Control / Communication Fault (Remote or BMS)
F16
Heater shows F16 and will not start; may occur after incorrect wiring or power issues.
Line Voltage / Power Supply Fault
F17
Heater displays F17; unit may start but then shuts down when water temperature is near setpoint.
Temperature Differential / Flow-Related Fault
F18
Heater shows F18 and will not run; may be associated with freeze protection or low ambient temperatures.
Ambient Temperature Sensor Fault / Freeze Sensor Error
F19
Heater displays F19; unit may lock out after several failed ignition attempts.
Ignition Lockout / Retry Limit Exceeded
F20
Heater shows F20; may be associated with internal safety chain faults.
Safety Circuit Open (Limit Chain / Flow / Pressure)
Symptom
Heater cabinet or nearby surfaces become excessively hot to the touch during operation.
Overheating Cabinet / Poor Ventilation
Symptom
Heater causes the pool pump to lose prime or shows air bubbles in the return when heater runs.
Hydraulic Interaction / Flow Restriction
Symptom
Heater cycles on and off frequently, with short run times and frequent restarts.
Short Cycling
Symptom
Heater display intermittently flickers or resets while running.
Intermittent Power / Low Voltage
Symptom
Heater display is on but unit does not respond to a call for heat from the pool automation system.
External Control / Automation Not Starting Heater
Symptom
Heater display shows incorrect water temperature compared to an external thermometer.
Temperature Reading Inaccurate
Symptom
Heater emits a strong gas smell around the unit, especially near the burner compartment.
Gas Leak / Incomplete Combustion
Symptom
Heater fan continues to run for an unusually long time after burners shut off.
Post-Purge Fan Overrun
Symptom
Heater fan runs but burners do not light; no error code is displayed.
No Ignition Without Code
Symptom
Heater is leaking water from the bottom of the cabinet.
Water Leak / Internal Plumbing Leak
Symptom
Heater keypad buttons are unresponsive or require very hard presses.
Keypad Wear / Water Ingress
Symptom
Heater makes loud banging or knocking noises during operation.
Water Hammer / Boiling in Heat Exchanger
Symptom
Heater operates but creates a whistling or high-pitched noise from the gas train.
Gas Flow Resonance / Orifice Noise
Symptom
Heater produces soot or black staining on the exhaust outlet or nearby surfaces.
Sooting / Poor Combustion
Symptom
Heater runs but pool water does not reach the set temperature or heats very slowly.
Underheating / Insufficient Heat Output
Symptom
Heater starts normally but shuts off after a few minutes, long before reaching set temperature.
Premature Shutdown
Symptom
Heater trips the electrical breaker when attempting to start.
Electrical Short / Overcurrent
Symptom
Heater vibrates excessively or rattles loudly when the fan is running.
Mechanical Vibration / Fan Imbalance
Symptom
Heater will not start at all; display is completely blank and unlit.
No Power / Dead Unit
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| F01 |
Heater will not start; display shows F01 shortly after a call for heat.
|
Water Flow Fault / Insufficient Water Flow | View Details |
| F02 |
Heater attempts to start but shuts down with F02; fan may run briefly then stop.
|
Air Flow Fault / Fan or Pressure Switch Error | View Details |
| F03 |
Heater locks out with F03; unit may start then quickly shut down without heating water.
|
Ignition Failure / No Flame Detected | View Details |
| F04 |
Heater starts but shuts down with F04; may light briefly then extinguish.
|
Flame Loss / Unstable Flame | View Details |
| F05 |
Display shows F05 and heater will not fire; may occur immediately on startup.
|
High Limit Switch Open / Overheat Protection | View Details |
| F06 |
Heater displays F06 and will not operate; may occur intermittently.
|
Outlet Water Temperature Sensor Fault | View Details |
| F07 |
Heater shows F07 and shuts down; may occur during operation as water warms.
|
Inlet Water Temperature Sensor Fault | View Details |
| F08 |
Display shows F08; heater will not respond to thermostat changes.
|
Water Temperature Sensor Mismatch / Calibration Error | View Details |
| F09 |
Heater displays F09 and will not ignite; may click but no flame appears.
|
Gas Valve or Gas Supply Fault | View Details |
| F10 |
Heater shows F10 and shuts down; may occur randomly during operation.
|
Flame Sensor Circuit Fault | View Details |
| F11 |
Display shows F11; heater may not respond to keypad inputs or may behave erratically.
|
User Interface / Keypad Communication Error | View Details |
| F12 |
Heater shows F12 and will not start; may occur after a power surge or lightning event.
|
Control Board Internal Fault | View Details |
| F13 |
Heater displays F13; unit may start but shuts down quickly without heating.
|
Exhaust Temperature Overlimit / Flue Sensor Fault | View Details |
| F14 |
Heater shows F14 and refuses to start; may be accompanied by fan not running.
|
Fan Speed / RPM Feedback Fault | View Details |
| F15 |
Display shows F15; heater may start but then shuts down with no obvious mechanical issue.
|
External Control / Communication Fault (Remote or BMS) | View Details |
| F16 |
Heater shows F16 and will not start; may occur after incorrect wiring or power issues.
|
Line Voltage / Power Supply Fault | View Details |
| F17 |
Heater displays F17; unit may start but then shuts down when water temperature is near setpoint.
|
Temperature Differential / Flow-Related Fault | View Details |
| F18 |
Heater shows F18 and will not run; may be associated with freeze protection or low ambient temperatures.
|
Ambient Temperature Sensor Fault / Freeze Sensor Error | View Details |
| F19 |
Heater displays F19; unit may lock out after several failed ignition attempts.
|
Ignition Lockout / Retry Limit Exceeded | View Details |
| F20 |
Heater shows F20; may be associated with internal safety chain faults.
|
Safety Circuit Open (Limit Chain / Flow / Pressure) | View Details |
| – |
Heater cabinet or nearby surfaces become excessively hot to the touch during operation.
|
Overheating Cabinet / Poor Ventilation | View Details |
| – |
Heater causes the pool pump to lose prime or shows air bubbles in the return when heater runs.
|
Hydraulic Interaction / Flow Restriction | View Details |
| – |
Heater cycles on and off frequently, with short run times and frequent restarts.
|
Short Cycling | View Details |
| – |
Heater display intermittently flickers or resets while running.
|
Intermittent Power / Low Voltage | View Details |
| – |
Heater display is on but unit does not respond to a call for heat from the pool automation system.
|
External Control / Automation Not Starting Heater | View Details |
| – |
Heater display shows incorrect water temperature compared to an external thermometer.
|
Temperature Reading Inaccurate | View Details |
| – |
Heater emits a strong gas smell around the unit, especially near the burner compartment.
|
Gas Leak / Incomplete Combustion | View Details |
| – |
Heater fan continues to run for an unusually long time after burners shut off.
|
Post-Purge Fan Overrun | View Details |
| – |
Heater fan runs but burners do not light; no error code is displayed.
|
No Ignition Without Code | View Details |
| – |
Heater is leaking water from the bottom of the cabinet.
|
Water Leak / Internal Plumbing Leak | View Details |
| – |
Heater keypad buttons are unresponsive or require very hard presses.
|
Keypad Wear / Water Ingress | View Details |
| – |
Heater makes loud banging or knocking noises during operation.
|
Water Hammer / Boiling in Heat Exchanger | View Details |
| – |
Heater operates but creates a whistling or high-pitched noise from the gas train.
|
Gas Flow Resonance / Orifice Noise | View Details |
| – |
Heater produces soot or black staining on the exhaust outlet or nearby surfaces.
|
Sooting / Poor Combustion | View Details |
| – |
Heater runs but pool water does not reach the set temperature or heats very slowly.
|
Underheating / Insufficient Heat Output | View Details |
| – |
Heater starts normally but shuts off after a few minutes, long before reaching set temperature.
|
Premature Shutdown | View Details |
| – |
Heater trips the electrical breaker when attempting to start.
|
Electrical Short / Overcurrent | View Details |
| – |
Heater vibrates excessively or rattles loudly when the fan is running.
|
Mechanical Vibration / Fan Imbalance | View Details |
| – |
Heater will not start at all; display is completely blank and unlit.
|
No Power / Dead Unit | View Details |
No matching codes found
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