What occurs within the furnace during forced draft operation?

During forced draft operation, a fan or blower is used to introduce air into the furnace, which increases the pressure inside the combustion chamber. This pressurization allows for a more efficient combustion process, as it ensures that there is a specific and controlled amount of air mixed with fuel, promoting a more complete burn and better heat transfer. The increased air pressure also helps to overcome any negative pressure that could be present in the surrounding environment, ensuring that the combustion gases are effectively expelled from the furnace.

Pressurizing the furnace can also contribute to safety by preventing unwanted air leaks into the combustion area, which could lead to inefficiencies and hazardous situations. This mode of operation enhances overall system performance and fuel efficiency.