H1
Buderus Fan Fault / Fan Speed Too Low

Boiler displays H1; burner does not start, fan may run

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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

Worn or seized fan motor, Obstruction in fan or flue, Faulty fan speed sensor, Control board not supplying correct voltage to fan

How to Fix / Troubleshooting

Safety: Isolate power and gas. Do not run the boiler with a faulty fan.

  • 1. Visual and manual check: With power off, access the fan and try to rotate it by hand. It should spin freely without scraping noises.
  • 2. Clean fan and air path: Remove dust and debris from the fan blades and air intake. Check that the flue is not blocked.
  • 3. Electrical test: A technician should measure the supply voltage to the fan and check the feedback (tachometer) signal to the control board.
  • 4. Replace fan: If the fan is noisy, stiff, or not reaching speed, replace it with the correct Buderus fan assembly.
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Repair Difficulty

Hard 4/5

Required Part

Fan Assembly
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