Ideal boiler displays H4, often with poor hot water performance
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: Hot water pipework can be very hot. Do not remove boiler covers.
User checks:
- Reset: Power cycle and reset the boiler once.
- Check hot water demand: Ensure hot taps are fully open and flow is adequate; very low flow can cause temperature instability.
Engineer tasks: Test the DHW NTC thermistor resistance, ensure it is firmly attached to the plate heat exchanger, replace the sensor if faulty, and check PCB input.
Repair Difficulty
Required Part
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