Burner indicates lockout due to internal temperature sensor or control overheating

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.

Possible Causes

Control box mounted too close to hot surfaces, Blocked ventilation around burner, High ambient temperature in furnace room, Failing control box temperature sensor

How to Fix / Troubleshooting

Safety: Turn off power and allow the burner and furnace to cool.

Steps:

Improve ventilation: Ensure the burner compartment has adequate airflow and is not sealed without vents.
Check mounting: Verify the control box is correctly mounted on the Riello burner and not touching the heat exchanger or flue.
Reduce ambient heat: Remove stored items blocking airflow around the furnace. Ensure other heat sources are not directed at the burner.

If A12 recurs under normal ambient conditions, the control box may need replacement.

Repair Difficulty

Medium 3/5

Required Part

Riello Burner Control Box

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