Q. What is the purpose of a furnace filter?

Answer:

Inexpensive fiberglass filters are used in furnaces to remove airborne particles that might damage the fan and the heating coil. Particle build-up can also decrease the efficiency of your furnace, as the furnace has to work harder to pull air through the intake. More expensive filters, such as pleated media, can also improve the air quality in your house by removing pollen, bacteria and mold spores from the air. This is especially important if you or someone in your family suffers from allergies.