The typical central heating and air conditioning system is actually a large loop type of system. This means the air that passes thorough the HVAC system circulates in an endless loop for as long as the system is running. The loop begins when air comes into the system through the return ducts in the AC system. The air passes through the ductwork and the HVAC systems filters. From there, the filtered air is passed through the main system where it is cooled or heated then back out through the ductwork and into the building.

There is little that can be done to improve the quality of the air that is being circulated through the system aside from replacing the return vent air filters. The selection of your HVAC system’s air filters directly affects the quality of air being circulated throughout the system.

The air in a furnace or air conditioning system first enters the home through the air return vent where it passes through the air filter(s) and into the air handler, over the cooling coils or heat exchanger part of the HVAC system (where the air is either cooled or heated) and out through the ductwork into the home. The circulation throughout the HVAC system is accomplished through a powerful blower system. Because the air filter is the only device in the entire HVAC system capable of removing airborne impurities, it makes sense that frequent replacement of the return vent air filter as well as careful consideration as to the type of air filter you use will directly impact the quality of your indoor air. Conversely, ignoring the HVAC systems air filter means you are allowing the entry of polluted air into the entire system, driving down operating efficiency, filling up ductwork with all dust, pollen, dust mites, etc. and other airborne pollutants while exposing the building’s inhabitants to polluted air.

A central air and heating system works this way: air comes into the home through the return air vent and passes through the vital return vent filters. After that the air goes into the air handler, over the cooling or heat exchanger part of the HVAC system. The air is heated or cooled here and is distributed by the ductwork into the home. A powerful blower system is needed in order to successfully circulate the air. The return vent filters are vitally important at this point because it alone controls the kind of air that finds its way into your house and straight to your family.

According to the American Lung Association, in 1999, 85% of Americans did not realize the air in their homes might be a health hazard. However, more people are becoming increasingly aware of the importance of the quality of air that we breathe indoors. We take for granted the cleanliness of our indoor air. The average person spends 90% of their time indoors, may it be at a store, bank, school, etc. therefore making it vital to our health that we are informed on improving our indoor air quality. And the main way to do that is to change the air filters in our systems every 60 to 90 days.

Asthma, allergies, and other respiratory problems are affecting millions of people, and are on the rise. It is no wonder that researchers are studying the effects of indoor air quality on these ailments. In a 1996 survey, it showed that in 58% of homes at least one humidity-related or respiratory problem was present in the form of allergies, asthma, persistent coughs, and/ or nasal congestion. In 36% of the homes, at least one household member suffered from at least one respiratory ailment.