🔍 Key Concepts

• Combustion air-fuel ratio in oil-fired boilers • Effects of insufficient air vs. ignition problems on smoke color • Difference between electrical ignition faults and combustion adjustment faults

💭 Think About

• Which of these choices would most directly change how completely the fuel burns, rather than whether it ignites at all? • When combustion is incomplete and too rich (too much fuel, not enough air), what color is the smoke usually and why? • Which options deal mainly with spark/ignition, and which deal mainly with air supply or fuel flow control?

✅ Before You Answer

• Identify which choice directly affects primary air to the flame and therefore completeness of combustion • Separate ignition system problems (electrodes, high-tension leads) from air-fuel mixture problems • Consider which fault would allow the burner to keep running but with sooty, black exhaust rather than failing to light or shutting down