Vokera Flow Switch / Flow Sensor Fault (DHW or CH depending on model)

Boiler displays 12; heating demand is not recognized, or the boiler cycles rapidly.

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 domestic hot water flow switch, sticking turbine flow sensor, blocked inlet filter, wiring fault to PCB.

Safety first: Isolate electrical power and close the cold water isolation valve before removing any water components.

Check hot water flow: Open a hot tap fully. If the flow is weak, clean tap aerators and check that stopcocks are fully open.
Engineer tasks:
- Remove and clean the DHW inlet filter on the Vokera boiler.
- Inspect and clean the flow sensor/turbine; check for limescale or debris.
- Test the flow switch or sensor output to the PCB.

Do not force or overtighten plastic sensor housings; they can crack and leak.

Medium 3/5

DHW Flow Sensor / Flow Switch

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