FC — Gas valve faulty, modulation valve control faulty, or vent system blocked

What does FC mean?

The burner is in a fault mode due to a problem with the gas valve, its modulation control, or a blockage in the vent system.

• Malfunctioning gas valve
• Faulty modulation valve control
• Blocked vent system (flue or air intake)

Click steps to track your progress.

1. 1

   Press the reset button 'R' on the boiler.

2. 2

   Check that the boiler's vent terminal (flue) outside is clear of obstructions like snow, ice, or debris.

3. 3

   Contact a qualified heating technician to check the gas valve, modulation valve control, and thoroughly inspect the vent system.