What is one method of increasing natural draft in a system?

Increasing the stack height is an effective method for enhancing natural draft in a system. The principle behind this is based on the fact that natural draft relies on the buoyancy of hot gases, which rise due to their lower density compared to colder ambient air. By elevating the height of the stack, the column of hot gases can rise higher, allowing for a more significant differential pressure between the inside of the stack and the outside atmosphere.

As the stack height increases, the upward draft improves because the wind effect and the temperature difference can create a stronger pull on the gases, promoting better air circulation and exhaust flow. This enhanced upward movement minimizes the risk of backdrafts and improves the efficiency of combustion processes, leading to better overall performance of the heating system.

Other methods mentioned in the choices, such as decreasing stack height or reducing fan speed, would typically decrease the effectiveness of the draft. Changing the fuel type, while it may influence combustion characteristics, does not directly address the mechanics of draft enhancement in the same way that increasing stack height does. This understanding of stack dynamics is crucial for efficient operation in systems relying on natural draft mechanisms.