Red Seal Gasfitter — Class B Practice Exam

What can insufficient air supply to a gas appliance cause?

1. Enhanced efficiency

2. Increased heat output

3. Incomplete combustion

4. Faster gas flow

The correct answer is: Incomplete combustion

Insufficient air supply to a gas appliance primarily leads to incomplete combustion. Gas appliances require a specific mixture of gas and air to burn efficiently and completely. When the air supply is inadequate, the fuel does not combust fully, which can result in the production of carbon monoxide and other harmful byproducts, as well as a decrease in the overall efficiency of the appliance. This phenomenon not only poses safety risks but can also decrease the performance of the appliance due to the accumulation of soot and other residues. In contrast, enhanced efficiency, increased heat output, and faster gas flow are outcomes that would typically be associated with an optimal fuel-to-air ratio. Insufficient air supply does not support these positive effects, but rather leads to the inverse, which highlights the critical role of proper ventilation in ensuring safe and effective gas appliance operation.