Boiler shows 11, will not start, may indicate low water pressure or circulation fault

Safety first: Allow the system to cool before topping up pressure. Use only the filling loop as described in the Vokera manual.

• Check pressure gauge: If below 0.8 bar when cold, top up to 1.0–1.5 bar using the filling loop. Close the valves fully afterwards.
• Bleed radiators: Remove trapped air and re-pressurise as needed.
• Inspect for leaks: Look around radiators, valves, and under the boiler for signs of water.
• Engineer checks:
  • Test the system pressure sensor or switch.
  • Inspect and clean any magnetic or inline filters.
  • Check pump operation and system design for adequate circulation.

If pressure keeps dropping, a leak or expansion vessel issue is likely and needs professional attention.