CTC
DHW Production Failure
Boiler runs but produces no domestic hot water, or hot water is only lukewarm.
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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
Faulty DHW flow sensor, Stuck diverter valve, Scaled plate heat exchanger, Incorrect DHW temperature setting
How to Fix / Troubleshooting
Safety: Turn off power and close water isolation valves before removing DHW components.
- Check settings: On the CTC control panel, verify that DHW mode is enabled and the set temperature is appropriate.
- Test DHW demand: Open a hot tap fully and observe if the boiler recognises demand (flame symbol or DHW icon). If not, suspect the DHW flow sensor.
- Check diverter operation (technician): During DHW demand, feel the heating flow pipe. It should cool while the DHW outlet heats. If not, the diverter valve may be stuck in heating position.
- Descale plate heat exchanger (technician): In hard water areas, remove and chemically descale or replace the DHW plate heat exchanger.
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Repair Difficulty
Medium
3/5
Required Part
DHW Plate Heat Exchanger
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