Vokera
Inconsistent DHW Temperature Control
Water heater provides hot water but temperature fluctuates between 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
Scaled DHW plate heat exchanger, Faulty DHW NTC sensor, Modulating gas valve issue, Inadequate water flow rate
How to Fix / Troubleshooting
Safety first: Risk of scalding from sudden temperature changes. Use caution when testing.
User checks:
- Ensure the shower mixer is suitable for use with a combi/instantaneous water heater and is not a gravity-type mixer.
- Open the hot tap or shower to a steady, moderate flow; very low flow can cause cycling.
- Check that cold mains pressure is not excessively higher than hot, which can upset some mixers.
Engineer steps:
- Inspect and descale the DHW plate heat exchanger if restricted.
- Test the DHW NTC sensor and replace if readings are unstable.
- Verify correct gas valve modulation and combustion settings.
Persistent temperature fluctuation usually requires professional servicing of the DHW circuit.
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Repair Difficulty
Medium
3/5
Required Part
DHW Plate Heat Exchanger
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