Defro
No DHW Production on Combi Boiler
Boiler display shows normal operation but there is no hot water at taps; heating works fine.
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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
Failed DHW flow sensor on Defro boiler, Stuck diverter valve not moving to DHW position, Blocked plate heat exchanger, Closed cold water isolation valve to Defro boiler
How to Fix / Troubleshooting
Safety: Turn off power and close cold inlet before removing DHW components.
- Check cold inlet valve: Ensure the cold water isolation valve under the Defro boiler is fully open.
- Observe boiler response: Open a hot tap and watch the boiler display. If it does not indicate DHW demand, the flow sensor may be faulty (see E14).
- Diverter test: If the boiler shows DHW demand but radiators heat instead of taps, the diverter valve is likely stuck and needs servicing or replacement.
- Plate exchanger: If there is some lukewarm water but not hot, the plate heat exchanger may be blocked and require descaling or replacement.
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Repair Difficulty
Medium
3/5
Required Part
Defro DHW flow sensor turbine
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