Boiler displays E10 and will not start; often associated with low water pressure or empty system.

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

Steps:

• Top up system: Locate the filling loop (flexible hose or built‑in valves) under the Attack boiler. Open the valves slowly until the pressure gauge reaches the recommended cold pressure (usually 1.0–1.5 bar), then close both valves fully.
• Bleed and recheck: Bleed radiators to remove air, then recheck pressure and adjust if necessary.
• Inspect for leaks: Check all visible pipework, radiator valves, and the boiler underside for drips or stains. Also inspect the discharge pipe from the safety valve outside.
• Expansion vessel check: If pressure rises very high when hot and drops to zero when cold, the internal or external Attack expansion vessel may have lost charge or failed.

Professional help: Persistent pressure loss or suspected expansion vessel failure should be handled by a heating engineer.