Error 09; unit indicates low water pressure or no water in the primary circuit.

Safety: Allow the unit to cool before adding water to avoid thermal shock.

• Check pressure gauge: On combination models, verify that the system pressure is within the recommended range (typically 1.0–1.5 bar when cold). If low, use the filling loop to add water slowly.
• Bleed air: After filling, bleed radiators or high points and recheck pressure, topping up as needed.
• Inspect for leaks: Look around the Immergas heater and connected pipework for signs of water leakage, especially at safety valves, pump unions, and heat exchanger connections.
• Check pressure sensor/switch: Locate the pressure sensor or switch on the hydraulic group. Ensure its connector is secure. If a sensing tube is used, remove and clear any blockage.

Important: If pressure drops repeatedly, there is likely a leak or expansion vessel fault that should be investigated by a technician.