Massachusetts Oil Burner License Practice Test

What occurs when combustion air is reduced in an oil burner?

1. Efficiency increases

2. Fuel consumption drops

3. Flame stability improves

4. Combustion efficiency decreases

The correct answer is: Combustion efficiency decreases

When combustion air is reduced in an oil burner, combustion efficiency decreases. This is because sufficient air is necessary for complete combustion of the fuel. Without enough air, not all of the fuel can be burned, leading to the production of carbon monoxide and unburned hydrocarbons. This incomplete combustion not only reduces the efficiency of the burner but also can lead to increased emissions, which are harmful to the environment and can indicate that the system is not operating correctly. In contrast, efficiency increases—often mistakenly thought—actually occurs when there is an optimal mix of fuel and air, while insufficient air leads to poor combustion performance. Flame stability typically relies on an adequate airflow to maintain a consistent flame; thus, reducing the combustion air can lead to instability rather than improvement. Fuel consumption does not necessarily drop because less efficient burns may require more fuel to achieve the same heat output, contradicting the notion that less fuel is used when air is restricted.