Aquacomfort
Aquacomfort 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 call for heat.
Water Flow Fault / Low Water Flow
F02
Heater attempts to start but shuts down with F02; fan may run briefly.
Ignition Failure / No Flame Detected
F03
Heater locks out with F03 after several failed ignition attempts; blower may run, but no sustained flame.
Flame Loss During Operation
F04
Display shows F04 and heater will not fire; may occur immediately when calling for heat.
High Limit Switch Open / Overheat Protection
F05
Heater displays F05 and shuts down; blower may not start.
Exhaust Temperature Fault / Flue Overheat
F06
F06 appears and heater will not start; fan does not run or runs briefly then stops.
Blower / Inducer Fault
F07
Heater shows F07 and will not fire; may occur after a power surge or storm.
Control Board Communication Error
F08
Display shows F08; heater does not respond to thermostat changes.
Water Temperature Sensor (Thermistor) Fault
F09
Heater displays F09 and will not start; may be intermittent.
Outlet Water Temperature Sensor Fault
F10
F10 appears and heater shuts down; may occur during long run cycles.
Inlet Water Temperature Sensor Fault
F11
Heater shows F11; fan may run but ignition sequence does not start.
Air Pressure Switch / Prover Fault
F12
F12 error; heater will not respond to external controls or local keypad.
User Interface / Keypad Fault
F13
Heater displays F13 and shuts down; may coincide with very cold ambient conditions.
Freeze Sensor / Ambient Temperature Sensor Fault
F14
F14 appears; heater may start but then shuts down unexpectedly.
Gas Valve Circuit Fault
F15
Heater shows F15; no call for heat is recognized from external automation.
External Control / Communication Fault
F16
F16 error; heater will not start and may blow internal fuse repeatedly.
Low Voltage Power Supply Fault
F17
Heater displays F17; unit may start but then shuts down when water temperature nears setpoint.
Thermostat Calibration / Setpoint Fault
F18
F18 appears; heater shuts down during operation, often on very hot days.
Cabinet Overheat / Internal Temperature Fault
F19
Heater shows F19; may coincide with low line voltage or brownouts.
Line Voltage Out of Range
F20
F20 error; heater will not start and may indicate a safety chain problem.
Safety Circuit Open
F21
Heater displays F21; may occur after lightning or electrical work.
EEPROM / Configuration Memory Error
F22
F22 appears; heater may run at reduced capacity or not at all.
Gas Type / Manifold Pressure Configuration Error
F23
Heater shows F23; unit may short-cycle or fail to reach set temperature.
Bypass Valve / Internal Flow Control Fault
F24
F24 error; heater may not detect water flow correctly even when pump is running.
Water Pressure Switch Calibration Fault
F25
Heater displays F25; may coincide with erratic blower speed or noise.
Blower Speed / RPM Feedback Fault
Symptom
Heater cabinet shows signs of rust, especially around the base and vent connections.
Corrosion / Environmental Damage
Symptom
Heater cabinet vibrates excessively or rattles loudly when running.
Mechanical Vibration / Loose Components
Symptom
Heater display is dim, flickering, or unreadable.
Display / Power Regulation Issue
Symptom
Heater display is on but buttons do not respond or respond intermittently.
Unresponsive Keypad / Interface
Symptom
Heater emits a strong gas smell around the unit, especially at startup.
Gas Leak or Incomplete Ignition
Symptom
Heater fan runs but burners do not light; no error code is shown.
Silent Ignition Failure
Symptom
Heater is leaking water from the bottom of the cabinet.
Internal Water Leak
Symptom
Heater makes loud banging or popping noises during operation.
Kettling / Boiling in Heat Exchanger
Symptom
Heater produces soot, black staining on the cabinet, or dark exhaust.
Sooting / Incomplete Combustion
Symptom
Heater runs but pool water does not heat up or heats very slowly, with no error code displayed.
Insufficient Heat Output / Underheating
Symptom
Heater runs but spa overheats well beyond the set temperature.
Overheating / Runaway Temperature
Symptom
Heater shuts off when the pump speed drops to low, even though water is still circulating.
Low Flow at Variable Pump Speeds
Symptom
Heater starts and stops frequently (short cycling) without reaching the desired pool temperature.
Short Cycling / Premature Shutdown
Symptom
Heater trips the household breaker or GFCI when it starts.
Electrical Short / Overcurrent
Symptom
Heater will not start at all; display is blank and no lights are on.
No Power / Dead Unit
Symptom
Heater will not start when controlled by pool automation, but works when operated manually.
Remote Control Integration Issue
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| F01 |
Heater will not start; display shows F01 shortly after call for heat.
|
Water Flow Fault / Low Water Flow | View Details |
| F02 |
Heater attempts to start but shuts down with F02; fan may run briefly.
|
Ignition Failure / No Flame Detected | View Details |
| F03 |
Heater locks out with F03 after several failed ignition attempts; blower may run, but no sustained flame.
|
Flame Loss During Operation | View Details |
| F04 |
Display shows F04 and heater will not fire; may occur immediately when calling for heat.
|
High Limit Switch Open / Overheat Protection | View Details |
| F05 |
Heater displays F05 and shuts down; blower may not start.
|
Exhaust Temperature Fault / Flue Overheat | View Details |
| F06 |
F06 appears and heater will not start; fan does not run or runs briefly then stops.
|
Blower / Inducer Fault | View Details |
| F07 |
Heater shows F07 and will not fire; may occur after a power surge or storm.
|
Control Board Communication Error | View Details |
| F08 |
Display shows F08; heater does not respond to thermostat changes.
|
Water Temperature Sensor (Thermistor) Fault | View Details |
| F09 |
Heater displays F09 and will not start; may be intermittent.
|
Outlet Water Temperature Sensor Fault | View Details |
| F10 |
F10 appears and heater shuts down; may occur during long run cycles.
|
Inlet Water Temperature Sensor Fault | View Details |
| F11 |
Heater shows F11; fan may run but ignition sequence does not start.
|
Air Pressure Switch / Prover Fault | View Details |
| F12 |
F12 error; heater will not respond to external controls or local keypad.
|
User Interface / Keypad Fault | View Details |
| F13 |
Heater displays F13 and shuts down; may coincide with very cold ambient conditions.
|
Freeze Sensor / Ambient Temperature Sensor Fault | View Details |
| F14 |
F14 appears; heater may start but then shuts down unexpectedly.
|
Gas Valve Circuit Fault | View Details |
| F15 |
Heater shows F15; no call for heat is recognized from external automation.
|
External Control / Communication Fault | View Details |
| F16 |
F16 error; heater will not start and may blow internal fuse repeatedly.
|
Low Voltage Power Supply Fault | View Details |
| F17 |
Heater displays F17; unit may start but then shuts down when water temperature nears setpoint.
|
Thermostat Calibration / Setpoint Fault | View Details |
| F18 |
F18 appears; heater shuts down during operation, often on very hot days.
|
Cabinet Overheat / Internal Temperature Fault | View Details |
| F19 |
Heater shows F19; may coincide with low line voltage or brownouts.
|
Line Voltage Out of Range | View Details |
| F20 |
F20 error; heater will not start and may indicate a safety chain problem.
|
Safety Circuit Open | View Details |
| F21 |
Heater displays F21; may occur after lightning or electrical work.
|
EEPROM / Configuration Memory Error | View Details |
| F22 |
F22 appears; heater may run at reduced capacity or not at all.
|
Gas Type / Manifold Pressure Configuration Error | View Details |
| F23 |
Heater shows F23; unit may short-cycle or fail to reach set temperature.
|
Bypass Valve / Internal Flow Control Fault | View Details |
| F24 |
F24 error; heater may not detect water flow correctly even when pump is running.
|
Water Pressure Switch Calibration Fault | View Details |
| F25 |
Heater displays F25; may coincide with erratic blower speed or noise.
|
Blower Speed / RPM Feedback Fault | View Details |
| – |
Heater cabinet shows signs of rust, especially around the base and vent connections.
|
Corrosion / Environmental Damage | View Details |
| – |
Heater cabinet vibrates excessively or rattles loudly when running.
|
Mechanical Vibration / Loose Components | View Details |
| – |
Heater display is dim, flickering, or unreadable.
|
Display / Power Regulation Issue | View Details |
| – |
Heater display is on but buttons do not respond or respond intermittently.
|
Unresponsive Keypad / Interface | View Details |
| – |
Heater emits a strong gas smell around the unit, especially at startup.
|
Gas Leak or Incomplete Ignition | View Details |
| – |
Heater fan runs but burners do not light; no error code is shown.
|
Silent Ignition Failure | View Details |
| – |
Heater is leaking water from the bottom of the cabinet.
|
Internal Water Leak | View Details |
| – |
Heater makes loud banging or popping noises during operation.
|
Kettling / Boiling in Heat Exchanger | View Details |
| – |
Heater produces soot, black staining on the cabinet, or dark exhaust.
|
Sooting / Incomplete Combustion | View Details |
| – |
Heater runs but pool water does not heat up or heats very slowly, with no error code displayed.
|
Insufficient Heat Output / Underheating | View Details |
| – |
Heater runs but spa overheats well beyond the set temperature.
|
Overheating / Runaway Temperature | View Details |
| – |
Heater shuts off when the pump speed drops to low, even though water is still circulating.
|
Low Flow at Variable Pump Speeds | View Details |
| – |
Heater starts and stops frequently (short cycling) without reaching the desired pool temperature.
|
Short Cycling / Premature Shutdown | View Details |
| – |
Heater trips the household breaker or GFCI when it starts.
|
Electrical Short / Overcurrent | View Details |
| – |
Heater will not start at all; display is blank and no lights are on.
|
No Power / Dead Unit | View Details |
| – |
Heater will not start when controlled by pool automation, but works when operated manually.
|
Remote Control Integration Issue | View Details |
No matching codes found
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