Alberta Boilers Safety Association (ABSA) Practice Test

Which gas is primarily associated with reduced combustion efficiency in furnaces?

1. Carbon monoxide

2. Sulphur dioxide

3. Nitrogen dioxide

4. Ozone

The correct answer is: Carbon monoxide

The gas primarily associated with reduced combustion efficiency in furnaces is carbon monoxide. This occurs because carbon monoxide is a byproduct of incomplete combustion, indicating that the fuel is not being burned efficiently. When combustion is inefficient, the amount of energy extracted from the fuel decreases, leading to lower overall efficiency in the furnace. In complete combustion, the fuel reacts fully with oxygen to produce carbon dioxide and water, maximizing energy release. However, if there is insufficient oxygen or poor mixing of the fuel and air, some of the carbon in the fuel does not convert to carbon dioxide, resulting in the formation of carbon monoxide instead. Furthermore, the presence of carbon monoxide is a safety concern, as it is a toxic gas. Its detection typically triggers maintenance or operational adjustments to ensure that furnaces operate safely and efficiently. While other gases mentioned can impact air quality or indicate specific combustion issues, they are not directly linked to combustion efficiency in the same way that carbon monoxide is.