Alpha Heating Demand / Diverter Valve Fault

Boiler does not fire for central heating but provides hot water normally.

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

Stuck diverter valve in DHW position, Faulty room thermostat or programmer, Faulty CH NTC sensor, PCB not recognising CH demand

Safety: Isolate power before removing covers.

Check controls: Ensure the programmer is set to HEATING ON and the room thermostat is turned up.
Observe boiler display: Many Alpha boilers show a CH demand symbol. If this is absent, the issue is likely with external controls.
Diverter valve test (qualified person): When CH is requested, feel the flow pipe from the boiler. If it stays cold while DHW works, the diverter valve may be stuck and require cleaning or replacement.
Sensor check: Verify CH NTC readings and wiring.

Hard 4/5

Diverter Valve Assembly

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