Fondital Inconsistent DHW Temperature Control

Domestic hot water temperature fluctuates between hot and cold during shower use

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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

Scaled DHW plate heat exchanger on Fondital boiler, Faulty DHW NTC sensor, Inadequate minimum gas rate adjustment, Flow sensor intermittently failing

How to Fix / Troubleshooting

Safety: Risk of scalding. Test water carefully and avoid sudden changes in tap position.

User checks:

  • Stable flow: Keep a steady, moderate flow at the tap or shower. Very low or very high flow can cause instability.
  • Other taps: Avoid opening multiple hot taps simultaneously during troubleshooting.
  • Clean aerators: Remove and clean tap/shower aerators to ensure consistent flow.

Technician actions:

  • Descale or replace the DHW plate heat exchanger.
  • Test and replace the DHW NTC sensor if readings are erratic.
  • Check and adjust gas valve minimum and maximum rates according to Fondital procedures.
  • Inspect and test the DHW flow sensor or turbine.
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Repair Difficulty

Medium 3/5

Required Part

DHW Plate Heat Exchanger
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