What type of draft fan is located before the furnace?

A forced draft fan is located before the furnace to facilitate the movement of air into the combustion process. This type of fan actively pushes air into the furnace, ensuring that the combustion process receives a consistent and adequate supply of oxygen. By maintaining the necessary airflow, the forced draft fan helps to optimize combustion efficiency and enhances the overall performance of the boiler system.

In contrast, induced draft fans are typically used to draw flue gases out of the furnace and create a negative pressure within the combustion chamber, which improves exhaust gas removal. Natural draft relies on the buoyancy of heated air to create airflow without mechanical assistance, and negative draft indicates a situation where the air pressure inside the furnace is lower than that outside. Therefore, these alternatives do not perform the function of introducing fresh air into the furnace as effectively as a forced draft fan.