Gas Heat ESCO Practice Exam

Which factor primarily influences the combustion efficiency in a gas furnace?

1. Type of fuel

2. Amount of nitrogen

3. Speed of the fan

4. Air-to-fuel ratio

The correct answer is: Air-to-fuel ratio

The air-to-fuel ratio is a critical factor in determining combustion efficiency in a gas furnace. This ratio refers to the amount of air mixed with the fuel during the combustion process. If the air-to-fuel ratio is optimized, it ensures complete combustion, leading to maximum energy extraction from the fuel and minimal emissions of unburned hydrocarbons. When the air-to-fuel ratio is too low, insufficient oxygen is available for complete combustion, resulting in wasted fuel and potentially harmful emissions such as carbon monoxide. Conversely, if the ratio is too high, it can cause excess heat loss through the flue gases and decreased efficiency. Therefore, maintaining the correct balance is crucial for optimal performance and energy efficiency in gas heating systems.