Technical description
This indicates that the Burner has fired up and is heating your system.
What causes this fault?
This is a normal operational status and not a mechanical failure. It occurs because the boiler’s internal controls have detected a demand for heat and have successfully ignited the burner to warm the water. Once your home reaches the desired temperature, this light will eventually turn off as the boiler enters standby mode.
You will see this more frequently during the winter months when your central heating is running for longer periods to keep your home warm.
DIY fix possible
This fault may be fixable without an engineer. Check your manual first.