Buderus Insufficient DHW Output

Boiler runs but hot water is only lukewarm

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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 plate heat exchanger, Gas valve not opening fully, Incorrect DHW temperature setting, Flow rate too high for boiler capacity

How to Fix / Troubleshooting

Safety: Beware of sudden temperature changes when testing DHW.

  • 1. Check DHW setpoint: Verify the domestic hot water temperature setting on the Buderus control panel and increase if necessary within safe limits.
  • 2. Reduce flow: Partially close the hot tap to reduce flow and see if temperature increases, indicating a capacity or scaling issue.
  • 3. Clean inlet filter: Ensure stable inlet pressure by cleaning the cold water filter.
  • 4. Plate heat exchanger: Have a technician descale or replace the DHW plate heat exchanger if scaling is suspected.
  • 5. Gas valve and combustion: A technician should verify that the boiler reaches full DHW output and that gas settings are correct.
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Repair Difficulty

Hard 4/5

Required Part

DHW Plate Heat Exchanger / Gas Valve
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