Immergas DHW Production / Plate Heat Exchanger Fault

Boiler provides central heating but no domestic hot water, or hot water is only lukewarm.

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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

Blocked plate heat exchanger, Faulty DHW flow sensor, Diverter valve not fully moving to DHW position, Scaled DHW side

How to Fix / Troubleshooting

Safety: Water may be hot; isolate power and water before removing components.

  • Check DHW flow: Ensure good flow at hot taps. Clean tap filters and check stop valves.
  • Verify boiler response: When a hot tap is opened, the boiler should show a DHW demand. If not, the DHW flow sensor may be faulty and should be cleaned or replaced.
  • Plate heat exchanger cleaning (engineer): Remove the plate heat exchanger and chemically descale it, or replace if heavily blocked.
  • Diverter valve: Confirm that the diverter valve fully moves to DHW position during demand; replace if sticking.
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Repair Difficulty

Hard 4/5

Required Part

Plate Heat Exchanger
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