Boiler shows error 09, will not fire, may indicate low system pressure or water shortage.

Safety: Allow the boiler to cool before topping up. Do not exceed the pressure recommended in the Biasi manual (typically around 1.5 bar cold).

• Check pressure gauge: Look at the boiler's pressure gauge. If below 0.8–1.0 bar, the boiler may lock out.
• Top up via filling loop: Open the filling loop valves slowly and watch the gauge rise to about 1.2–1.5 bar, then close both valves firmly.
• Bleed radiators: After topping up, bleed radiators and recheck pressure, topping up again if necessary.
• Inspect for leaks: Look for visible water around radiators, valves, and under the boiler. Persistent pressure loss indicates a leak that must be repaired.
• Engineer checks: If pressure is correct but error 09 remains, a technician should test the water pressure switch or sensor and check the expansion vessel charge and connection.