'SF' and Green LEDs Flashing — Calibration Mode Active

What does SF + Green LEDs flashing mean?

This display indicates that the boiler has entered 'Calibration Mode', which is used by engineers for specific setup and testing (e.g., setting gas rates or CO2 levels). 'SF' will alternate with the current boiler temperature, and both green LEDs will flash. This is an operational status, not a fault.

• User or engineer intentionally initiated calibration mode by turning control knobs in a specific sequence (both knobs fully anticlockwise, then DHW knob 1/4 clockwise twice, then back fully anticlockwise).

Click steps to track your progress.

1. 1

   Recognize that this is a diagnostic mode, not an error. No action is required unless you are a qualified engineer.

2. 2

   To exit Calibration Mode, turn the right-hand (Domestic Hot Water temperature) knob in any direction.

3. 3

   The boiler will automatically exit this mode after 20 minutes if no further adjustments are made or if the maximum central heating temperature is reached.