Junkers
Unstable DHW Temperature Control
Domestic hot water temperature fluctuates, runs hot then cold during shower
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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 Junkers combi, Faulty DHW NTC sensor, Inadequate flow rate, Modulating gas valve issues
How to Fix / Troubleshooting
Safety first: Turn off power and close water valves before removing DHW components.
- 1. Check flow rate: Ensure the hot tap is opened sufficiently. Very low flow can cause temperature swings.
- 2. Clean inlet filters: Clean the cold water inlet filter to ensure stable flow.
- 3. Plate heat exchanger: A scaled plate heat exchanger can cause rapid overheating and shutdown. Remove and descale or replace the exchanger using appropriate chemicals and procedures.
- 4. DHW NTC: Test and replace the DHW temperature sensor if readings are unstable.
- 5. Professional gas valve check: A technician should verify correct modulation of the gas valve during DHW operation.
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Repair Difficulty
Hard
4/5
Required Part
DHW Plate Heat Exchanger
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