If you don’t change your grease filters, you’ll find they become filled with grease. This is a problem for many reasons including:
They may become fully blocked resulting in reduced air suction from the exhaust fan. You’ll then find that grease will start building up around the outside of the canopy, on your cooking equipment and potentially onto your food.
If the grease filters are partially blocked by grease, then there is still likely to be air suction through the canopy exhaust system. However, as the grease filters are ‘full’, the airborne grease will be sucked into the exhaust ductwork and will likely attach to the duct wall. This is a fire hazard and will help any fire spread from the canopy, into the ductwork and the rest of the building. It also makes the job of cleaning the exhaust ductwork much more difficult.