Klimosz DHW Flow Detection / Plate Heat Exchanger Fault

Boiler produces central heating but no domestic hot water (DHW) on a combi model.

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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

Faulty DHW flow sensor or flow switch on Klimosz combi, Blocked plate heat exchanger, Stuck diverter valve in heating position, Scaled DHW side

How to Fix / Troubleshooting

Safety: Turn off power and close cold water inlet before working on DHW components.

  • Check DHW demand: Open a hot tap fully and see if the boiler recognizes flow (DHW symbol on display). If not, suspect the flow sensor.
  • Inspect flow sensor: Remove and clean the DHW flow sensor or turbine. Replace if damaged or not spinning freely.
  • Check diverter valve: Ensure the valve moves to DHW position when a tap is opened. If not, the actuator or valve body may be faulty.
  • Descale plate exchanger: If DHW is lukewarm or flow is poor, the plate heat exchanger may be scaled. Remove and chemically descale or replace it.
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Repair Difficulty

Hard 4/5

Required Part

DHW Flow Sensor
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