Viadrus

Viadrus Furnaces Error Codes

Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.

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E01
Furnace does not ignite, burner does not start, control shows E01 shortly after a call for heat.
Ignition Failure / No Flame Establishment
E02
Furnace starts ignition sequence but shuts down with E02, indicating flame is not detected or lost shortly after ignition.
Flame Detection Failure
E03
Furnace attempts to start but locks out with E03, fan may run briefly, no ignition, often accompanied by a flue or air pressure warning icon.
Flue Gas Fan / Air Pressure Switch Fault
E04
Control displays E04 and the furnace shuts down; often occurs after overheating or poor circulation, heat exchanger very hot to the touch.
Overheat / Safety Thermostat Tripped
E05
Display shows E05 and the furnace will not start; often associated with a sensor icon or abnormal temperature reading.
Flow Temperature Sensor Fault (NTC Open/Short)
E06
Furnace locks out with E06, domestic hot water (if equipped) overheats or is cold, temperature readings fluctuate.
Return or DHW Temperature Sensor Fault
E07
Control shows E07 and the burner does not start; may occur immediately on power‑up.
Low System Water Pressure / Pressure Switch Open
E08
Furnace displays E08 and shuts down; may be accompanied by rapid temperature rise on the display.
Flow Temperature Too High / Overtemperature Cut‑Out
E09
Furnace shows E09, burner stops, and the flue gas temperature is abnormally high.
Flue Gas Temperature Sensor Fault / Overtemperature
E10
Control indicates E10, burner stops, and the display may show a symbol for external thermostat or safety loop.
External Safety Circuit Open (Limit Chain / Thermostat Loop)
E11
Furnace shows E11 and remains locked out; no response to thermostat, often after a power surge or wiring work.
Internal Control Board Fault / EEPROM Error
E12
Display shows E12, burner stops, and the circulation pump may continue to run.
Return Temperature Too Low / Condensation Protection
E13
Furnace indicates E13, burner stops, and there may be evidence of water around the base of the unit.
Water Leak / Low‑Water Cutoff Activation
E14
Control shows E14, burner does not start, and the gas valve does not click during ignition attempts.
Gas Valve Control Fault
E15
Furnace shows E15, burner stops, and the fan may continue to run for a purge period.
Flame Loss During Operation
E16
Display shows E16, no burner operation, and the fan may not start.
Fan Speed / Tachometer Fault
E17
Furnace indicates E17, burner stops, and the system may show signs of electrical interference or unstable operation.
Mains Voltage Out of Range
E18
Control shows E18, burner does not start, and the display may show a communication or bus symbol.
Communication Error Between Control Modules
Symptom
Black soot deposits around the flue outlet and on the heat exchanger surfaces, with dark smoke from chimney.
Sooting / Incomplete Combustion
Symptom
Corrosion and rust visible on the lower sections of the Viadrus cast‑iron furnace, with occasional water drops.
Condensation Corrosion / Low Return Temperature Damage
Symptom
Furnace and nearby pipework vibrate excessively, with humming or droning noise during operation.
Vibration / Resonance in Burner or Pump
Symptom
Furnace display is blank or unreadable, but the burner and pump still operate.
Display Module Failure
Symptom
Furnace emits a strong smell of gas near the burner compartment, especially during or after ignition attempts.
Gas Leak or Incomplete Ignition
Symptom
Furnace emits a strong smell of oil or visible oil mist around the burner (for Viadrus oil‑fired models).
Oil Leak or Poor Combustion
Symptom
Furnace fan runs continuously even when there is no call for heat and the burner is off.
Fan Stuck On / Control Relay Fault
Symptom
Furnace frequently short‑cycles (turns on and off rapidly) without maintaining stable room temperature.
Short Cycling / Control Misconfiguration
Symptom
Furnace ignites with a loud bang or pop, sometimes shaking the flue or burner door.
Delayed Ignition
Symptom
Furnace makes loud banging or knocking noises when starting or stopping, sometimes called water hammer or kettling.
Kettling / Boiling in Heat Exchanger
Symptom
Furnace runs but domestic hot water from the indirect cylinder is not hot enough or runs out quickly (on Viadrus systems with DHW cylinder).
Insufficient DHW Heating
Symptom
Furnace runs but radiators remain cold or only lukewarm, burner cycles frequently.
Insufficient Heat Output / Poor Circulation
Symptom
Furnace shuts down randomly without an error code, then restarts after a while.
Intermittent Overheat or Electrical Interruption
Symptom
Furnace will not start at all, no lights on the control panel, completely dead.
No Power to Furnace
Symptom
Radiators on upper floors are cold while lower ones heat normally when the Viadrus furnace is running.
Air Lock / Insufficient Head
Symptom
Room temperature overshoots the thermostat setting by several degrees before the Viadrus furnace shuts off.
Overheating / Control Overshoot
Symptom
Water leaking from the safety (pressure relief) valve discharge pipe near the Viadrus furnace.
Overpressure / Safety Valve Discharge
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