G2 Gas Fitter Practice Exam

What characterizes a natural draft burner?

1. It uses a fan for airflow

2. It requires mechanical assistance for combustion air

3. It is not equipped with a mechanical device for supplying combustion air

4. It operates at high gas pressure

The correct answer is: It is not equipped with a mechanical device for supplying combustion air

A natural draft burner is characterized by its reliance on the natural buoyancy of warm air to draw combustion air into the burner without the need for mechanical assistance. This means it does not utilize fans or other mechanical devices to supply air for combustion, which distinguishes it from forced draft burners that require such equipment. The absence of a mechanical device for supplying combustion air allows for simpler designs, making natural draft burners typically easier to maintain and operate under normal conditions. The function of natural draft relies on the stack effect, where warm air rises and creates a negative pressure that draws fresh air into the combustion chamber. This is fundamental to the operation of such burners, ensuring effective combustion through natural ventilation. While natural draft burners may exhibit certain operating pressures, they are not specifically defined by high gas pressure, nor do they incorporate fans for airflow, both of which apply to other types of burners designed for different operational demands.