What are the reasons for the more draught than normal in economiser?

In economizers, increased draught can occur due to several factors, including design inefficiencies, improper sizing, or blockages in the flue gas path. Additionally, a higher temperature differential between the flue gases and the ambient environment can enhance draught. Maintenance issues, such as dirty heat exchangers or malfunctioning fans, may also contribute to irregular airflow. Lastly, changes in fuel characteristics can affect combustion efficiency and alter draught levels.