The paper throwaway filters found in residential furnaces and air conditioners do not improve the air quality in the building. They are there to keep dirt out of system components such as fans and coils. On the other hand, the banks of filters found in commercial installations remove pollutants from the air as well as protect the equipment. The efficiency of a filter determines both the size of particles and percentage of particles that can be removed. Dirty filters release pollutants into the ventilation air and allow dirt to build up on coils and fans. Replace dirty filters carefully so the trapped pollutants are not released into the air again:

  • Wear a respirator to protect yourself.

  • Stop the fan.

  • Remove the new filters from their box.

  • Remove the old filters and put them into the empty box. Then, remove the box of dirty filters from the plenum or fan room.

  • Clean the plenum or fan room with a vacuum cleaner.

  • Install the new filters into the filter frames. Be sure the airflow arrows face in the right direction. Be sure that all the retainer clips are locked in place.

  • Start the fan.

    Adapted from Indoor Air Quality from the Indoor Environment Technician's Library series;

    Publication date: 05/23/2005