Biasi No / Insufficient Domestic Hot Water

Boiler runs for central heating but does not produce any domestic hot water, or hot water is only lukewarm.

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.

Possible Causes

Faulty DHW flow sensor, Blocked plate heat exchanger, Diverter valve stuck in heating position, DHW NTC sensor fault

Safety: Water may be unexpectedly hot or cold; test carefully.

Check DHW demand recognition: Open a hot tap and see if the boiler indicates DHW demand (icon or temperature change). If not, suspect the flow sensor.
Compare CH and DHW: If heating works well but DHW is poor, the issue is likely in the DHW circuit (plate heat exchanger, diverter, or sensors).
Engineer service: A technician can test the DHW flow sensor, descale or replace the plate heat exchanger, and check diverter valve operation and DHW NTC readings.

Hard 4/5

Plate Heat Exchanger

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