Water heater temperature fluctuates, alternating between hot and cold during a shower
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: Risk of scalding due to sudden temperature changes. Inform users not to stand directly under the shower while testing.
- Stabilize flow: Avoid fully opening multiple taps; maintain a steady, moderate flow at the shower.
- Clean flow sensor: Remove and clean the DHW flow sensor/turbine to ensure accurate flow measurement.
- Check NTC sensors: Monitor DHW temperature readings in diagnostics (if available). Replace any sensor with unstable readings.
- Gas valve modulation: Have a technician verify that the gas valve modulates smoothly and that gas pressure is stable.
Warning: Do not increase temperature setpoint to compensate for instability; fix the underlying control issue.
Repair Difficulty
Required Part
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