Display shows E10, unit shuts down, often associated with low system pressure on models with a sealed primary circuit.

Safety: Allow the system to cool before adding water. Overfilling can cause relief valve discharge.

• 1. Check Pressure Gauge: On ACV sealed systems, verify the pressure on the gauge. Typical cold pressure is around 1.0–1.5 bar (check the manual).
• 2. Top Up System: If pressure is low, open the filling loop or ACV automatic filling valve slowly and watch the gauge. Close the valve when the correct pressure is reached.
• 3. Bleed Air: Bleed radiators or high points in the primary circuit to remove trapped air, then recheck pressure and top up again if needed.
• 4. Inspect for Leaks: Look for water around the ACV water heater, safety valve discharge pipe, and visible pipework. Repair any leaks before relying on the unit.
• 5. Check Pressure Sensor: If the gauge shows correct pressure but E10 persists, the ACV pressure sensor or its wiring may be faulty and require replacement.

If pressure drops repeatedly, there is likely a leak or expansion vessel issue that should be investigated by a heating professional.