Baxi DUO TEC Boilers

The boiler has detected a problem with the electrical connection to the gas valve, which controls gas flow to the burner.

The boiler's external temperature probe is reporting an issue. This probe helps the boiler regulate heating based on outside conditions.

The boiler has detected an issue during the pre-circulation phase, which is when the pump runs before ignition to prepare the system.

The boiler's wireless (RF) external temperature probe is reporting a fault. This probe helps the boiler regulate heating based on outside conditions.

The boiler has detected that its internal temperature has exceeded a safe maximum limit, either rapidly (gradient) or due to general overheating. This often triggers a safety thermostat.

The boiler's safety thermostat has activated, indicating an overheat condition or a fault with the thermostat itself. This can prevent the boiler from operating safely.

The boiler has detected that the primary heating circuit water pressure is too high, exceeding 2.7 or 2.9 bar.

The boiler has detected that the primary heating circuit water pressure is too low, less than 0.5 bar.

The boiler's differential water flow switch indicates that there is no water flow when there should be, or it's stuck in an open position.

The boiler has detected an issue with water circulation in the primary heating circuit, often indicated by a lack of temperature change after ignition or rapid temperature changes.

The boiler has failed to reach the required temperature for the Antilegionella function, which purifies the domestic hot water tank.

The boiler has experienced a flame failure during normal burner operation, meaning the flame extinguished unexpectedly.

The boiler has repeatedly lost its flame during the ignition sequence, even with maximum correction attempts.

The boiler's differential water flow switch indicates that water is flowing when it shouldn't be, or it's stuck in a closed position.

The flue thermostat sensor has tripped, indicating excessively high temperatures in the flue, leading to a boiler lockout.

The boiler has failed to ignite, indicating a problem with the gas supply or the ignition system. This includes cases where the condensate trap is frozen or blocked.

The boiler's gas valve opened, but no flame was detected within the allowed time, indicating a lack of gas or an ignition issue.

The boiler has detected an issue with the gas valve connection or an internal fault on the main control board (PCB).

The boiler's main control board (PCB) is unable to correctly command or communicate with the gas valve.

The boiler's system has failed a plausibility test between the flow and return temperatures, suggesting an issue with water circulation or sensor readings.

The boiler has detected a problem with the fan, which is essential for proper combustion and flue gas extraction.

The low temperature safety thermostat has tripped, indicating that the boiler or system water temperature is too low for safe operation or has dropped unexpectedly.

This message indicates that the automatic water refill function is currently active. This is a status message, not a fault, and means the boiler is topping up its water levels.

The boiler's automatic water refill function has exceeded the maximum allowed time, suggesting a problem with filling the system.

The boiler's sensor for the central heating flow temperature is faulty, either short-circuited or open-circuited.

The boiler has activated its dry fire or overheat prevention system, indicating a risk of damage due to lack of water or excessive temperature.

The boiler's flue gas temperature sensor is faulty, either short-circuited or open-circuited.

The boiler has detected an incorrect electrical frequency (Hz) from the main power supply.

The boiler's sensor for the Domestic Hot Water (DHW) temperature is faulty, either short-circuited or open-circuited.

The boiler has detected a 'parasitic flame,' meaning it senses a flame when there shouldn't be one, or detects a flame signal incorrectly.

The boiler has detected that the incoming electrical power supply voltage is too low.

The boiler's sensor for the central heating return temperature is faulty, either short-circuited or open-circuited.

The boiler's water pressure test (either temporary or final) has failed, indicating a problem with the system's water circulation or pressure.

The boiler's aluminium sensor (likely a temperature sensor) is faulty, either short-circuited or open-circuited.

The boiler's sensor for the Domestic Hot Water (DHW) temperature, specifically for tank versions, is faulty.

The boiler has detected a blockage or obstruction in the flue pipe, which is critical for safe exhaust gas venting. This fault can lead to a lockout if not resolved promptly.

The boiler's main control board (PCB) has not been set or calibrated, which is necessary after replacement or certain system changes.

The boiler has detected wind conditions affecting the flue and has increased the minimum fan speed to compensate. This is usually a normal operational message, not a fault.

The boiler's combustion levels are outside the acceptable range, which can affect efficiency and safety. This might be related to fan speed or flame signal correction.

The boiler has detected an obstruction in the flue duct when operating at its minimum power setting.

The boiler has detected wind conditions affecting the flue while operating at maximum power.

The boiler has detected an unstable gas supply pressure, which can lead to inefficient operation or ignition problems.

The boiler is experiencing issues with its flame detection system, including possible brief interruptions of the flame signal.

During the automatic calibration process, the fan speed parameter was detected to be outside the acceptable operating range.

During the automatic calibration process, the combustion test results were found to be outside the acceptable range.

The boiler has detected a modified flame signal. This is a diagnostic message and typically does not require user action.

The boiler's internal current measurements, often related to flame detection, are outside the expected range.

The boiler has detected that the minimum current supplied to the gas valve is outside its normal operating limits.

The boiler has detected that the maximum current supplied to the gas valve is outside its normal operating limits.

The boiler is unable to communicate correctly with the room thermostat or other room control units.

The boiler's self-calibration process has triggered an alarm during the combustion test, indicating a problem with combustion.

The boiler is attempting to ignite but fails, or makes unusual noises. This suggests a problem with the internal fan, which is essential for proper air-fuel mixture and exhaust.

The boiler's control panel display is completely dark and unresponsive. This indicates a loss of electrical power to the boiler or a critical internal electrical fault.

The boiler is not providing heating or hot water, and the circulation pump may not be operating. This prevents hot water from reaching radiators or taps.

The central heating system pressure is outside the normal operating range, either too low or too high. This condition can prevent the boiler from functioning correctly and may lead to system shutdown.