🔍 Key Concepts

• Proper air-fuel ratio in oil-fired burners • Effects of insufficient air on combustion products (soot, carbon deposits, smoke) • Where combustion actually takes place in a marine furnace/boiler

💭 Think About

• If you throttle (partially close) the burner air register while fuel flow remains the same, what happens to the air supply and the completeness of combustion? • When combustion is incomplete, where is unburned carbon (soot) most likely to stick: right at the air register, or in the hotter furnace area where the flame actually burns? • Which choice describes a condition you would expect from too little air, versus a condition caused by too much air or higher temperature?

✅ Before You Answer

• Identify which options describe effects of insufficient air (think soot and carbon) versus excess air (cooler flame, lower efficiency). • Visualize the flame path: fuel and air mix at the burner tip/tilt, flame projects into the furnace — where would deposits logically build up when burning is not complete? • Eliminate any choices that contradict the basic rule: closing the air register reduces air supply, it does NOT increase excess air.