Boiler leaking water from underneath the casing

Safety first: Turn off power to the boiler and close the flow, return, and cold water isolation valves. Place a container or towels under the boiler to catch drips.

• Identify leak source (visual): Remove the front cover and carefully inspect all visible joints, the pump, the automatic air vent, and the plate heat exchanger for signs of fresh water.
• Check pressure behaviour: Note if system pressure drops when the boiler is off, which indicates a heating-side leak.
• Do not ignore corrosion: If you see rust or green staining on the main heat exchanger or fittings, contact an engineer promptly to prevent major failure.
• Engineer tasks: Tighten or remake leaking joints, replace faulty components (e.g., plate heat exchanger, AAV, pump seals), refill and bleed the system, and check for further leaks.