Which of the following is NOT a characteristic of forced draft in a boiler?

The characteristic of forced draft in a boiler involves maintaining a positive pressure within the combustion chamber. This pressure is created by a fan or blower that forces air into the combustion process, ensuring that sufficient air is available for efficient burning of fuel. Because forced draft systems operate by introducing air into the boiler, they are designed to increase efficiency by optimizing the combustion process.

A key trait of forced draft is that it is dependent on the operation of the fan. The fan’s operation is crucial for providing the necessary airflow to prevent backdrafts and enhance combustion efficiency.

By contrast, reduced air input is not consistent with the principles of forced draft; in fact, forced draft systems aim to increase the volume of air provided to the fuel being burned. Therefore, indicating that reduced air input is a characteristic of forced draft is incorrect, as it contradicts the fundamental operation of these systems.

In summary, forced draft is characterized by increased efficiency, positive pressure in the combustion area, and reliance on fan operation, rather than a reduction in air input.