Ideal boiler shows H5 and may shut down on high temperature
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: Overheating can cause very hot surfaces. Allow the boiler and radiators to cool before touching.
User checks:
- Bleed radiators: Remove trapped air, then re-pressurise the system to 1.0–1.2 bar.
- Open all radiator valves: Ensure good circulation throughout the system.
- Reduce flow temperature: Lower the central heating temperature on the boiler controls.
If H5 continues, a heating engineer should check pump operation, clean or replace the plate heat exchanger, and flush the system if heavily sludged.
Repair Difficulty
Required Part
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