Large amounts of combustible material in the furnace ash are usually a result of what?

The presence of large amounts of combustible material in the furnace ash is usually indicative of not enough forced draft. Forced draft refers to airflow that is mechanically induced into the furnace to support the combustion process. When there is insufficient forced draft, the airflow may not be adequate to promote complete combustion of the fuel. This incomplete combustion results in unburned fuel or other combustible materials ending up in the ash.

When combustion is efficient, the majority of the fuel should be consumed, leading to minimal combustible residues. However, without sufficient airflow, the fuel may not ignite or burn completely, and this deficiency manifests as excess combustible material in the ash. Proper forced draft ensures that the furnace operates optimally, enhancing combustion efficiency and reducing the presence of such materials.