If you Put a HEPA Filter on a House Air Conditioner?

HEPA, brief for high efficiency particulate air, filters cleanse air to medical-grade standards. A HEPA filter employs a thick, pleated media to eliminate over 99 percent of airborne particulates under a size of 0.3 microns, according to Mother Earth News. This includes nearly all toxic microorganisms including bacteria, mold spores and viruses. While in-duct HEPA filters could be appropriate for the powerful atmosphere quantity of a hospital central air system, many residential systems don’t create adequate airflow to overcome the air restriction caused by a HEPA filter.

More Filtration Equals Less Air Flow

The more efficient the filter press, the more it strangles duct lining. True HEPA filters are ranked above 16 — the highest rating recommended for non-commercial systems — on the HVAC sector’s Minimum Efficiency Reporting Value, or MERV, scale. Airflow restriction imposed by in-duct HEPA filters in residential ac systems decreases energy efficiency, reduces performance and can actually diminish indoor air quality by inducing anxiety imbalances.

Options for In-Duct Filters

An alternative to in-duct HEPA filtration is an external HEPA filter. Connected to the principal A/C ductwork with a smaller bypass duct, a blower in the filter draws some air out of the main duct, pushes it through the HEPA filter, then loops the filtered air back to the main airflow. This process continuously filters a proportion of the household airflow to HEPA standards without limiting air volume through the duct.

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