Sime
No DHW Production on Combi Boiler
Boiler provides heating but no domestic hot water on a combi system
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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, Blocked plate heat exchanger, Diverter valve stuck in heating position, DHW NTC sensor fault
How to Fix / Troubleshooting
Safety first: Allow the boiler to cool before removing covers; hot water components can be very hot.
- Check DHW demand recognition: Open a hot tap and watch the boiler display. If it does not show a tap symbol or DHW demand, the flow sensor is likely faulty.
- Engineer checks: The engineer should test and replace the DHW flow sensor, inspect and clean/replace the plate heat exchanger, and check operation of the diverter valve motor and cartridge.
- Temporary workaround: If heating works, you may be able to use an immersion heater (if fitted) until the boiler is repaired.
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Repair Difficulty
Hard
4/5
Required Part
DHW Diverter Valve Assembly
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