Kitchen exhaust fans remove grease particles, smoke and various smells from a cooking area. These fans come in two types: venting and recirculating. The vented exhaust fans channel the air outside, while the recirculating fans recycle the air back into the kitchen.
Venting kitchen exhaust fans have ductwork that usually leads to the roof or a side wall; builders use the shortest route possible to increase the efficiency of the fan. Located in a hood on top of the stove's burners, the exhaust fan's motor pulls air into the hood. It passes through filters to catch grease particles. The air is then pushed outside through the ductwork.
Recirculating kitchen exhaust fans work almost the same as vented fans. After the grease particles are filtered out, the air then goes through charcoal filters that absorb any cooking odors. The purified air is then directed back into the kitchen. No ductwork is required.
One advantage of the venting exhaust fan is that it vents steam from a room. This prevents condensation from building up in the kitchen. The recirculating exhaust fans are sometimes more practical in smaller kitchens or where it is difficult to run ductwork without a lot of bends. Both vents require regular cleaning or changing of the filters to maximize efficiency.