Chaffoteaux
Unstable DHW Temperature
Domestic hot water temperature fluctuates between hot and cold during use (combi models).
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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
Partially blocked plate heat exchanger, Faulty DHW NTC sensor, Inadequate flow rate through furnace, Modulating gas valve issues
How to Fix / Troubleshooting
Safety: Water may become very hot unexpectedly; use caution.
- Check flow rate: Open the hot tap fully. Very low flow can cause temperature swings. Clean tap aerators and shower heads to improve flow.
- Avoid mixing at tap: Initially test with only the hot tap open (no cold mixing) to see if the furnace maintains a stable temperature.
- Descale plate heat exchanger (professional): Limescale can restrict flow and cause overheating. A technician can remove and chemically clean or replace the plate heat exchanger.
- Check DHW sensor connection: Ensure the DHW NTC wiring is secure.
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Repair Difficulty
Medium
3/5
Required Part
Plate Heat Exchanger
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