Biasi
No Demand Recognition
Boiler display works but no response to hot water or heating demand, no fan or ignition sequence starts.
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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 PCB demand input, Broken wiring from thermostat or DHW flow sensor, Internal relay failure, Incorrect control wiring
How to Fix / Troubleshooting
Safety: Isolate power before working on control wiring.
- Verify demand: Confirm that the room thermostat and programmer are calling for heat and that a hot tap is fully opened for DHW.
- Check indicators: Many Biasi boilers show CH or DHW symbols when demand is detected. If these do not appear, the boiler is not seeing the demand.
- Inspect wiring: Check the low-voltage control terminals for loose or broken wires.
- Engineer diagnostics: A technician can test PCB inputs, relays, and external controls, replacing the PCB if internal faults are found.
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Repair Difficulty
Hard
4/5
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