Sime No Central Heating Output

Boiler provides hot water but no central heating on a combi or system boiler

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

Room thermostat or programmer not calling for heat, Diverter valve stuck in DHW position, Faulty CH NTC sensor, Pump not running

Safety first: Ensure the boiler is accessible and stable before working near it.

Check controls: Confirm that the heating program is on and the room thermostat is set above room temperature.
Check radiator valves: Ensure TRVs and lockshield valves are open.
Engineer tasks: The engineer should verify pump operation, test the CH NTC, and check the diverter valve for movement when switching between DHW and CH. Replace or service the diverter valve if stuck.

Medium 3/5

Diverter Valve Motor

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