The HVAC filter is one of the most crucial components of a forced-air heating and air-conditioning system. Without a filter, dust will get blown all over the house, thwarting your cleaning efforts and reducing indoor air quality. A neglected filter will clog with dust and debris, restricting airflow and reducing energy efficiency.

 

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A wide range of air filters are available: fiber-and-paper filters, widely used because they’re inexpensive and easy to handle; models made of polyester or fiberglass; HEPA (high efficiency particulate air) filters, for those with allergies or dust sensitivities; and even “permanent” filters that can be washed out and used repeatedly.

Single-use filters should be replaced at least once a month during the heating and cooling seasons, more often if the filter clogs with dust quickly. Some high-efficiency filters are designed for longer periods. This information will be part of the labeling on the product package.
 
Wash permanent filters by spraying any all-purpose household cleaning liquid on both sides of the filter, letting the cleaner work for several minutes and then rinsing the filter thoroughly from both sides. A hand-held showerhead or a garden hose (if it’s not too cold outside) both work well. Allow the filter to drain and dry completely before re-installing. If you live in a very cold climate and choose a permanent filter, buy two for alternating service: Take the dirty filter out, install the clean filter, and clean the dirty one as soon as possible. That way, you won’t have to shut off the heat while the filter dries.

Even if you buy good filters and replace or clean them regularly, some dust and dirt will sneak past and accumulate in the ductwork. Studies are under way to find out whether regular duct cleaning is beneficial or detrimental. See the entry Duct for more information.