G2 Gas Fitter Practice Exam

What produces a forced draft in an appliance?

1. A fan or blower

2. The shape of the chimney

3. The height of the flue pipe

4. The atmospheric pressure

The correct answer is: A fan or blower

A forced draft in an appliance is produced by a fan or blower. This component is responsible for actively moving air into the combustion chamber, which ensures a consistent and adequate supply of oxygen for the combustion process. The fan or blower creates a pressure difference that drives air into the appliance, which is essential for maintaining efficient and stable combustion. The other options do contribute to the function of a gas appliance but do not actively create a forced draft. The shape of the chimney and the height of the flue pipe are more related to natural draft systems, which rely on convection and the temperature difference between hot gases and cooler ambient air. Atmospheric pressure also influences combustion efficiency but is not the primary mechanism for generating a forced draft in appliances. These elements can affect how well an appliance performs, but they do not provide the active air movement that a fan or blower delivers.