A08
Beretta
Air Pressure Switch Fault / Combustion Air Proving Failure
Boiler shows A08, fan runs but ignition does not start, or boiler stops shortly after starting.
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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
Blocked flue or air intake, Faulty air pressure switch, Split or blocked pressure tubing, Fan not achieving required speed
How to Fix / Troubleshooting
Safety: Isolate power and gas before removing the combustion cover. Flue and combustion checks must be done by a qualified technician.
- Check flue terminal: From outside, ensure the flue outlet and air intake are clear.
- Technician – inspect pressure tubes: Remove and check silicone tubes from the fan to the air pressure switch for splits, kinks, or water. Replace or clear as needed.
- Technician – test air pressure switch: Using a manometer or multimeter, verify that the Beretta air pressure switch changes state when the fan runs. Replace if it does not operate correctly.
- Technician – fan speed: Confirm the fan receives correct voltage and reaches specified speed. Replace the fan if it is weak or noisy.
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Repair Difficulty
Professional Required
5/5
Required Part
Air Pressure Switch
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