Dimplex Internal Water Leak

Boiler leaking water from underneath the casing

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Leaking Dimplex pressure relief valve (PRV), Corroded Dimplex primary heat exchanger, Loose compression joints on Dimplex flow/return connections, Split Dimplex expansion vessel diaphragm causing PRV discharge

How to Fix / Troubleshooting

Safety first: Switch off power to the boiler and close the system isolation valves if possible. Place a container or towels under the boiler to catch water. Do not remove the combustion chamber cover.

User checks:

  • Pressure gauge: Note the system pressure. If it is above 2.5–3.0 bar, the PRV may be discharging due to overpressure.
  • PRV discharge pipe: Check outside where the copper PRV discharge pipe terminates. If water is dripping constantly, the Dimplex PRV is likely passing.
  • Do not keep topping up: Repeatedly topping up the system can worsen leaks and damage the boiler.

Professional repair:

  • Identify the exact source of the leak inside the Dimplex boiler.
  • Replace the Dimplex PRV, expansion vessel, or heat exchanger as required.
  • Refill, vent, and test the system for further leaks.
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Repair Difficulty

Hard 4/5

Required Part

Dimplex pressure relief valve
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