Boiler leaking water from underneath the casing or pipe connections

Safety first: Switch off power and close the boiler's isolation valves. Place a container or towels under the boiler to catch drips. Do not remove the combustion chamber seal yourself.

• Identify leak source (visual): Remove the lower cover (if user-removable) and use a torch to see where water is forming. Note whether it is from a pipe joint, pump, or relief pipe.
• Check pressure relief discharge: If water is coming from the copper pipe that exits outside, the pressure relief valve is passing. This often indicates an expansion vessel issue.
• Do not overtighten joints: Avoid over-tightening unions on the boiler; this can damage seals. Minor weeps may be temporarily contained with absorbent material until an engineer attends.
• Engineer repair: A qualified engineer should replace leaking components (pump seals, AAV, PRV, or heat exchanger) and check system pressure and inhibitor levels.