Hoval
Hoval Furnaces 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, furnace locks out shortly after start attempt.
Ignition failure lockout
A02
Burner starts, but the flame is unstable and goes out, followed by lockout.
Flame supervision failure
A03
The furnace attempts to start but shuts down due to overtemperature; the display shows an overheat alarm.
Primary limit / safety thermostat trip
A04
The furnace shuts down with a flue gas temperature alarm; a high flue temperature is displayed.
Flue gas overtemperature
A05
The furnace locks out with an air pressure / air proving fault; the burner fan runs but there is no ignition.
Combustion air pressure switch fault
A06
The furnace display shows a low water pressure / water shortage alarm; the burner is blocked.
System water pressure low
A07
The furnace shows a high water pressure alarm; the safety valve may discharge water.
System overpressure
A08
The furnace display indicates a flue gas sensor fault; the burner is inhibited.
Flue gas temperature sensor failure
A09
Furnace shows flow temperature sensor error, no heating operation.
Flow temperature sensor failure
A10
Furnace shows return temperature sensor error, heating curve control disabled.
Return temperature sensor failure
A11
Furnace indicates outside temperature sensor fault, weather-compensated control not working.
Outdoor sensor failure
A12
Furnace shows DHW (domestic hot water) sensor error, no hot water production.
DHW cylinder sensor failure
A13
Furnace display shows gas valve fault, burner does not start.
Gas valve control failure
A14
Furnace indicates fan fault, combustion fan does not run or runs erratically.
Combustion fan failure
A15
Furnace shows ignition transformer fault, no spark at burner.
Ignition transformer failure
A16
Furnace indicates ionization current too low, intermittent flame loss.
Weak flame signal
A17
Furnace shows safety chain open / safety loop error, burner inhibited.
Safety interlock circuit open
A18
Furnace indicates condensate fault, burner stops, possible water in base tray.
Condensate drainage failure
A19
Furnace shows a communication error with Hoval TopTronic or the main controller.
Controller communication failure
A20
Furnace indicates a power supply fault or undervoltage, leading to intermittent resets.
Mains supply / power module fault
A21
Furnace shows a pump fault; the circulation pump is not detected or is overloaded.
Heating circulation pump failure
A22
Furnace indicates flue gas recirculation or a CO alarm from an external sensor.
Flue gas spillage / CO hazard
A23
Furnace shows a burner lockout due to too many failed start attempts.
Repeated ignition lockout
A24
Furnace indicates a sensor plausibility error (e.g., flow and return temperatures are inconsistent).
Temperature sensor plausibility fault
A25
Furnace shows active frost protection / frost alarm; the burner may run unexpectedly at low temperatures.
Frost protection mode
Symptom
Burner flame appears yellow and sooty through the inspection window.
Poor combustion / sooting
Symptom
Condensate drain gurgles loudly and occasionally backs up.
Condensate drainage restriction
Symptom
Domestic hot water is excessively hot, risk of scalding.
Overheating DHW
Symptom
Furnace emits a high-pitched whine or humming during operation.
Fan or pump noise
Symptom
Furnace frequently loses pressure and needs topping up.
Chronic pressure loss
Symptom
Furnace makes loud banging or knocking noises when starting or stopping.
Water hammer / thermal expansion noise
Symptom
Furnace runs continuously and overshoots room temperature.
Room temperature control fault
Symptom
Furnace starts but shuts down after a few seconds without showing an error code.
Unstable operation / internal protection
Symptom
Radiators are hot but domestic hot water is cold.
No DHW production
Symptom
Strong smell of gas near the Hoval furnace.
Gas leak
Symptom
The furnace frequently cycles on and off with short run times.
Short cycling
Symptom
The furnace is completely dead; there is no display or lights.
No power to the furnace
Symptom
The furnace runs but does not provide enough heat to the building.
Insufficient heat output
Symptom
Visible white steam or flue gas escaping around the furnace casing or flue joints.
Flue gas leakage
Symptom
Water leaking from the bottom of the Hoval furnace.
Internal water leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A01 |
Burner does not ignite, furnace locks out shortly after start attempt.
|
Ignition failure lockout | View Details |
| A02 |
Burner starts, but the flame is unstable and goes out, followed by lockout.
|
Flame supervision failure | View Details |
| A03 |
The furnace attempts to start but shuts down due to overtemperature; the display shows an overheat alarm.
|
Primary limit / safety thermostat trip | View Details |
| A04 |
The furnace shuts down with a flue gas temperature alarm; a high flue temperature is displayed.
|
Flue gas overtemperature | View Details |
| A05 |
The furnace locks out with an air pressure / air proving fault; the burner fan runs but there is no ignition.
|
Combustion air pressure switch fault | View Details |
| A06 |
The furnace display shows a low water pressure / water shortage alarm; the burner is blocked.
|
System water pressure low | View Details |
| A07 |
The furnace shows a high water pressure alarm; the safety valve may discharge water.
|
System overpressure | View Details |
| A08 |
The furnace display indicates a flue gas sensor fault; the burner is inhibited.
|
Flue gas temperature sensor failure | View Details |
| A09 |
Furnace shows flow temperature sensor error, no heating operation.
|
Flow temperature sensor failure | View Details |
| A10 |
Furnace shows return temperature sensor error, heating curve control disabled.
|
Return temperature sensor failure | View Details |
| A11 |
Furnace indicates outside temperature sensor fault, weather-compensated control not working.
|
Outdoor sensor failure | View Details |
| A12 |
Furnace shows DHW (domestic hot water) sensor error, no hot water production.
|
DHW cylinder sensor failure | View Details |
| A13 |
Furnace display shows gas valve fault, burner does not start.
|
Gas valve control failure | View Details |
| A14 |
Furnace indicates fan fault, combustion fan does not run or runs erratically.
|
Combustion fan failure | View Details |
| A15 |
Furnace shows ignition transformer fault, no spark at burner.
|
Ignition transformer failure | View Details |
| A16 |
Furnace indicates ionization current too low, intermittent flame loss.
|
Weak flame signal | View Details |
| A17 |
Furnace shows safety chain open / safety loop error, burner inhibited.
|
Safety interlock circuit open | View Details |
| A18 |
Furnace indicates condensate fault, burner stops, possible water in base tray.
|
Condensate drainage failure | View Details |
| A19 |
Furnace shows a communication error with Hoval TopTronic or the main controller.
|
Controller communication failure | View Details |
| A20 |
Furnace indicates a power supply fault or undervoltage, leading to intermittent resets.
|
Mains supply / power module fault | View Details |
| A21 |
Furnace shows a pump fault; the circulation pump is not detected or is overloaded.
|
Heating circulation pump failure | View Details |
| A22 |
Furnace indicates flue gas recirculation or a CO alarm from an external sensor.
|
Flue gas spillage / CO hazard | View Details |
| A23 |
Furnace shows a burner lockout due to too many failed start attempts.
|
Repeated ignition lockout | View Details |
| A24 |
Furnace indicates a sensor plausibility error (e.g., flow and return temperatures are inconsistent).
|
Temperature sensor plausibility fault | View Details |
| A25 |
Furnace shows active frost protection / frost alarm; the burner may run unexpectedly at low temperatures.
|
Frost protection mode | View Details |
| – |
Burner flame appears yellow and sooty through the inspection window.
|
Poor combustion / sooting | View Details |
| – |
Condensate drain gurgles loudly and occasionally backs up.
|
Condensate drainage restriction | View Details |
| – |
Domestic hot water is excessively hot, risk of scalding.
|
Overheating DHW | View Details |
| – |
Furnace emits a high-pitched whine or humming during operation.
|
Fan or pump noise | View Details |
| – |
Furnace frequently loses pressure and needs topping up.
|
Chronic pressure loss | View Details |
| – |
Furnace makes loud banging or knocking noises when starting or stopping.
|
Water hammer / thermal expansion noise | View Details |
| – |
Furnace runs continuously and overshoots room temperature.
|
Room temperature control fault | View Details |
| – |
Furnace starts but shuts down after a few seconds without showing an error code.
|
Unstable operation / internal protection | View Details |
| – |
Radiators are hot but domestic hot water is cold.
|
No DHW production | View Details |
| – |
Strong smell of gas near the Hoval furnace.
|
Gas leak | View Details |
| – |
The furnace frequently cycles on and off with short run times.
|
Short cycling | View Details |
| – |
The furnace is completely dead; there is no display or lights.
|
No power to the furnace | View Details |
| – |
The furnace runs but does not provide enough heat to the building.
|
Insufficient heat output | View Details |
| – |
Visible white steam or flue gas escaping around the furnace casing or flue joints.
|
Flue gas leakage | View Details |
| – |
Water leaking from the bottom of the Hoval furnace.
|
Internal water leak | View Details |
No matching codes found
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