How to Fix / Troubleshooting

Safety: Turn off power and close the isolation valves to the boiler. Allow the appliance to cool before inspecting.

Steps:

Remove the front panel and inspect all visible joints, pump, heat exchanger, and valves for signs of water tracks or staining.
Check the pressure relief valve discharge pipe; if water is present, the PRV may be passing and should be replaced after checking system pressure and expansion vessel.
Inspect the automatic air vent on top of the pump or heat exchanger for leaks; tighten or replace if necessary.
If the pump body or seals are leaking, replace the pump or pump head with a genuine Protherm part.
Corroded or leaking heat exchangers generally require replacement by a qualified technician.

After repair: Re‑pressurize the system, bleed air, and monitor for further leaks.

Boiler leaking water from underneath the casing

Possible Causes