Baxi
Temperature Modulation / Flow Control Instability
Water heater produces hot water but temperature is unstable, alternating between very hot and cold during a 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
Partially blocked plate heat exchanger on Baxi DHW circuit, Faulty DHW NTC sensor, Inconsistent gas pressure, Flow sensor reading incorrectly due to limescale
How to Fix / Troubleshooting
Safety: Risk of scalding. Warn users and avoid maximum temperature settings until resolved.
Steps:
- Check flow rate: Very low flow can cause overshooting. Try increasing flow by opening the tap more.
- Clean inlet filter: A restricted inlet can cause unstable flow; clean as described in the manual.
- Descale plate heat exchanger: In hard water areas, the Baxi plate heat exchanger can scale up. A professional should isolate and chemically descale or replace it.
- Sensor check: Ensure the DHW NTC sensor is firmly attached and not corroded.
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Repair Difficulty
Hard
4/5
Required Part
Plate Heat Exchanger (DHW)
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