Blue light Fast flash with 2 pulses — Boiler not responding to any demand

What does Blue light Fast flash 2 pulses mean?

The blue indicator light performs a fast flash with two distinct pulses, meaning the boiler is failing to operate for both central heating and hot water demands. This indicates a general demand or control issue.

• Temperature control set in frost protection position
• Unintended live demand at ST10-LR from external system
• Faulty control board or timer issue

Click steps to track your progress.

1. 1

   Ensure the boiler's temperature control knob is not set in the frost protection position.

2. 2

   Check the external timer or programmer settings to ensure it is correctly calling for heat.

3. 3

   Verify there is no unintended external system demand at ST10-LR preventing normal operation.

4. 4

   If issues persist, contact a qualified technician to check the control board or timer.