Heater shows F19, often with erratic temperature control or overshooting setpoint.

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, Sticking modulating gas valve, Incorrect sensor calibration, PCB modulation error

Safety: Isolate power and water before removing any hydraulic components.

Check DHW flow sensor: Inspect the sensor on the cold inlet for secure wiring and absence of leaks.
Clean inlet filter: Remove and clean any inlet strainer to ensure stable flow.
Observe operation: With a hot tap open, watch the temperature display. Large swings may indicate sensor or modulation issues requiring professional diagnosis.
Do not adjust gas settings: Leave gas valve calibration to a qualified engineer.

Hard 4/5

DHW Flow Sensor

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