Ideal Central Heating Demand or Diverter Valve Fault

No heating but hot water works correctly on an Ideal combi boiler

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Safety Warning

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.

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Possible Causes

Stuck diverter valve in hot water position, Faulty room thermostat or programmer, Motorised diverter head failure, Blocked or closed heating valves

How to Fix / Troubleshooting

Safety first: Ensure the boiler is cool before touching any pipework. Do not remove the boiler case.

User checks:

  • Controls: Confirm the room thermostat is turned up and calling for heat, and that the programmer is set to ON or timed.
  • Radiator valves: Ensure TRVs and lockshields are open.
  • Mode selection: On the boiler, ensure central heating mode is enabled (not hot water only).

If hot water continues to work but radiators stay cold, an engineer should test the diverter valve assembly, replace the diverter motor head if seized, and check control wiring.

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Repair Difficulty

Medium 3/5

Required Part

Diverter Valve Assembly
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