Fondital
Fondital Water Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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A01
Burner does not ignite, display shows A01 shortly after a hot water or heating demand.
Ignition Failure / No Flame Detection
A02
Burner lights briefly then shuts down, display shows A02 during operation.
Flame Loss During Operation
A03
Unit locks out with A03, fan may run briefly then stop, burner does not light.
Flue Gas Safety / Overheat or Flue Thermostat Intervention
A04
Display shows A04, burner does not start, often after overheating or poor circulation.
Primary Circuit Overheat / Safety Thermostat Tripped
A05
Error A05 appears, fan may run continuously or not at all, burner does not ignite.
Fan / Air Pressure Switch Fault
A06
Display shows A06, burner shuts down, often associated with ignition noise or delayed ignition.
Ignition Control / Flame Signal Instability
A07
Unit displays A07 and stops, often after running for some time at high temperature.
Domestic Hot Water (DHW) Overtemperature
A08
Error A08 appears, unit may start then quickly stop, sometimes accompanied by gurgling noises.
Low Water Flow / Circulation Fault
A09
Display shows A09, unit refuses to start, often after a power outage or wiring work.
Flow Switch / DHW Flow Sensor Fault
A10
Error A10, unit may start but then shut down, sometimes with fluctuating temperature readings.
Primary NTC Sensor Fault (Flow Temperature Sensor)
A11
Display shows A11, unit may run only in limited mode or not at all.
Return NTC Sensor Fault
A12
Error A12, unit may lock out immediately on start-up.
DHW NTC Sensor Fault
A13
Display shows A13, often associated with very low or no system pressure indication.
Water Pressure Switch / Sensor Fault
A14
Error A14, unit may run only at reduced power or shut down intermittently.
Gas Valve Modulation Fault
A15
Display shows A15, often after a power surge or lightning event.
Control Board Communication / Internal Fault
A16
Error A16, unit may not respond to thermostat or user commands.
Room Thermostat / External Control Fault
A17
Display shows A17, often associated with condensate issues on condensing models.
Condensate Drain / Trap Fault
A18
Error A18, unit may shut down when switching between DHW and heating.
Diverter Valve Position Fault
A19
Display shows A19, often with irregular fan speed or noise.
Fan Speed / Tachometer Fault
A20
Error A20, unit may lock out with no obvious mechanical issue.
Flame Detection Circuit Fault (False Flame or No Flame Signal)
Symptom
Display is on but unresponsive, buttons do not work or respond intermittently.
User Interface / Keypad Fault
Symptom
Hot water temperature fluctuates when other taps or appliances are used.
DHW Flow Instability / Hydraulic Imbalance
Symptom
Water heater cycles on and off rapidly when a hot tap is open, causing unstable temperature.
Short Cycling in DHW Mode
Symptom
Water heater does not respond to room thermostat, heats only when hot water is used.
Heating Demand Not Recognized
Symptom
Water heater does not start at all, no lights or display, completely dead.
No Power / Main Supply Failure
Symptom
Water heater drips from the condensate pipe even when not running.
Condensate Backflow / Siphoning
Symptom
Water heater emits a burning smell or shows signs of overheating plastic parts.
Electrical Overheating / Component Failure
Symptom
Water heater emits a metallic banging or kettling noise when heating.
Heat Exchanger Kettling
Symptom
Water heater frequently loses pressure and needs refilling.
Chronic Pressure Loss
Symptom
Water heater ignites with a loud bang or popping noise.
Delayed Ignition
Symptom
Water heater leaks water from the bottom of the casing.
Internal Water Leak
Symptom
Water heater makes a whistling or howling noise during operation.
Combustion Resonance / Gas Flow Noise
Symptom
Water heater produces lukewarm water only, not reaching set temperature.
Insufficient DHW Temperature
Symptom
Water heater runs but produces no hot water, outlet water remains cold.
No DHW Production
Symptom
Water heater vibrates excessively or is very noisy when the fan runs.
Mechanical Vibration / Fan Imbalance
Symptom
Water heater’s fan runs but burner does not ignite, no error code displayed.
Pre-ignition Purge Without Ignition
Symptom
Water heater’s flue terminal shows signs of soot or black staining.
Poor Combustion / Sooting
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A01 |
Burner does not ignite, display shows A01 shortly after a hot water or heating demand.
|
Ignition Failure / No Flame Detection | View Details |
| A02 |
Burner lights briefly then shuts down, display shows A02 during operation.
|
Flame Loss During Operation | View Details |
| A03 |
Unit locks out with A03, fan may run briefly then stop, burner does not light.
|
Flue Gas Safety / Overheat or Flue Thermostat Intervention | View Details |
| A04 |
Display shows A04, burner does not start, often after overheating or poor circulation.
|
Primary Circuit Overheat / Safety Thermostat Tripped | View Details |
| A05 |
Error A05 appears, fan may run continuously or not at all, burner does not ignite.
|
Fan / Air Pressure Switch Fault | View Details |
| A06 |
Display shows A06, burner shuts down, often associated with ignition noise or delayed ignition.
|
Ignition Control / Flame Signal Instability | View Details |
| A07 |
Unit displays A07 and stops, often after running for some time at high temperature.
|
Domestic Hot Water (DHW) Overtemperature | View Details |
| A08 |
Error A08 appears, unit may start then quickly stop, sometimes accompanied by gurgling noises.
|
Low Water Flow / Circulation Fault | View Details |
| A09 |
Display shows A09, unit refuses to start, often after a power outage or wiring work.
|
Flow Switch / DHW Flow Sensor Fault | View Details |
| A10 |
Error A10, unit may start but then shut down, sometimes with fluctuating temperature readings.
|
Primary NTC Sensor Fault (Flow Temperature Sensor) | View Details |
| A11 |
Display shows A11, unit may run only in limited mode or not at all.
|
Return NTC Sensor Fault | View Details |
| A12 |
Error A12, unit may lock out immediately on start-up.
|
DHW NTC Sensor Fault | View Details |
| A13 |
Display shows A13, often associated with very low or no system pressure indication.
|
Water Pressure Switch / Sensor Fault | View Details |
| A14 |
Error A14, unit may run only at reduced power or shut down intermittently.
|
Gas Valve Modulation Fault | View Details |
| A15 |
Display shows A15, often after a power surge or lightning event.
|
Control Board Communication / Internal Fault | View Details |
| A16 |
Error A16, unit may not respond to thermostat or user commands.
|
Room Thermostat / External Control Fault | View Details |
| A17 |
Display shows A17, often associated with condensate issues on condensing models.
|
Condensate Drain / Trap Fault | View Details |
| A18 |
Error A18, unit may shut down when switching between DHW and heating.
|
Diverter Valve Position Fault | View Details |
| A19 |
Display shows A19, often with irregular fan speed or noise.
|
Fan Speed / Tachometer Fault | View Details |
| A20 |
Error A20, unit may lock out with no obvious mechanical issue.
|
Flame Detection Circuit Fault (False Flame or No Flame Signal) | View Details |
| – |
Display is on but unresponsive, buttons do not work or respond intermittently.
|
User Interface / Keypad Fault | View Details |
| – |
Hot water temperature fluctuates when other taps or appliances are used.
|
DHW Flow Instability / Hydraulic Imbalance | View Details |
| – |
Water heater cycles on and off rapidly when a hot tap is open, causing unstable temperature.
|
Short Cycling in DHW Mode | View Details |
| – |
Water heater does not respond to room thermostat, heats only when hot water is used.
|
Heating Demand Not Recognized | View Details |
| – |
Water heater does not start at all, no lights or display, completely dead.
|
No Power / Main Supply Failure | View Details |
| – |
Water heater drips from the condensate pipe even when not running.
|
Condensate Backflow / Siphoning | View Details |
| – |
Water heater emits a burning smell or shows signs of overheating plastic parts.
|
Electrical Overheating / Component Failure | View Details |
| – |
Water heater emits a metallic banging or kettling noise when heating.
|
Heat Exchanger Kettling | View Details |
| – |
Water heater frequently loses pressure and needs refilling.
|
Chronic Pressure Loss | View Details |
| – |
Water heater ignites with a loud bang or popping noise.
|
Delayed Ignition | View Details |
| – |
Water heater leaks water from the bottom of the casing.
|
Internal Water Leak | View Details |
| – |
Water heater makes a whistling or howling noise during operation.
|
Combustion Resonance / Gas Flow Noise | View Details |
| – |
Water heater produces lukewarm water only, not reaching set temperature.
|
Insufficient DHW Temperature | View Details |
| – |
Water heater runs but produces no hot water, outlet water remains cold.
|
No DHW Production | View Details |
| – |
Water heater vibrates excessively or is very noisy when the fan runs.
|
Mechanical Vibration / Fan Imbalance | View Details |
| – |
Water heater’s fan runs but burner does not ignite, no error code displayed.
|
Pre-ignition Purge Without Ignition | View Details |
| – |
Water heater’s flue terminal shows signs of soot or black staining.
|
Poor Combustion / Sooting | View Details |
No matching codes found
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