Which component does NOT contribute to the creation of a mechanical draft?

The heat exchanger is not a component that contributes to mechanical draft. Its primary function is to transfer heat between two or more fluids, enabling efficient heating or cooling processes. While it plays a crucial role in heat transfer within a system, it does not create or control the airflow necessary for a mechanical draft.

In contrast, the other components like blowers, fans, and injectors are specifically designed to move air or gases, thereby creating a draft. A blower utilizes mechanical energy to force air or exhaust out of a system, enhancing the efficiency of venting. A fan operates similarly by moving air, often in residential or commercial spaces, to ensure adequate airflow. An injector, typically used in combustion systems, relies on the venturi effect to draw in air or exhaust gases, also aiding in draft generation. Therefore, these components directly contribute to the mechanical draft's formation by manipulating air movement, whereas the heat exchanger does not.