12
Biasi
Gas Valve / Flame Control Fault
Boiler displays error 12, fan runs but ignition does not occur, may indicate gas valve or flame sensing issue.
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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
Faulty gas valve coil, Loose gas valve wiring, Incorrect gas valve adjustment, PCB output fault to gas valve
How to Fix / Troubleshooting
Safety: Turn off power and isolate the gas supply. Only a Gas Safe (or equivalent) engineer must work on gas valves.
- Observe ignition sequence: On reset, check if you hear the igniter clicking but no flame appears. This suggests the gas valve is not opening.
- Check gas isolation valve: Confirm the boiler's gas cock is fully open.
- Engineer electrical tests: A technician should measure voltage at the gas valve during ignition, check coil resistance, and verify correct earthing.
- Combustion checks: After any gas valve replacement or adjustment, a full combustion analysis must be carried out to Biasi specifications.
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Repair Difficulty
Professional Required
5/5
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