Main Diverter Valve Stuck in Heating Position

Boiler does not fire for hot water unless heating is also on (combi models)

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

Sticking diverter valve cartridge, Faulty diverter motor/actuator, Debris in valve body, Incorrect installation of valve head

Safety: Isolate power and water before working on the diverter valve. Components may be hot.

Test DHW demand: Turn heating off at the programmer and open a hot tap. If the boiler does not fire or radiators heat when tap is open, the diverter is suspect.
Engineer actions:
- Inspect and replace the diverter valve cartridge on the Main combi boiler.
- Test the diverter motor/actuator and replace if not driving the valve.
- Flush the system to remove debris that may cause sticking.

Hard 4/5

Diverter Valve

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