BoilerFaultCodesTechnical description
Heat exchanger antifreeze active, as fan speed variation is too high. Appliance is within the waiting time of the operation block function
What causes this fault?
This fault happens when the boiler's internal sensors detect that the fan is struggling to maintain a steady speed, which can occur if there is a sudden restriction in airflow. To protect the heat exchanger from potentially freezing due to this irregular air movement, the system enters a temporary waiting period. It is usually caused by a failing fan motor or an issue with the electronic signals between the fan and the control board.
This fault is more frequent during the winter months, as cold external temperatures can trigger the safety software to prioritize frost protection when airflow issues are detected.
DIY fix possible
Check the external flue pipe for any obstructions like leaves or debrisIf the weather is extremely cold, check if the condensate pipe has frozenTurn the boiler power off and back on to reset the countdown timer