High-efficiency air filters offer a number of advantages, but they also come with certain drawbacks. HEPA filters are very effective, but they are also thick and dense, which can interfere with the airflow process of your HVAC equipment. As filtration efficiency increases, so does the system airflow restriction caused by the filter. For this reason, HEPA filtration is not suitable for all residential systems.
An HVAC contractor can measure airflow and tell you if your system can support HEPA filtration in the duct. Alternatively, residential HEPA filtration options include whole-house air filters that connect to the ductwork through a bypass circuit. These units draw air from the duct, transport it through the HEPA filter assembly, and then loop it back into the duct without restricting airflow. It's important to remember that the air in your home is recirculated, so the same air will pass through the filter several times a day.
A HEPA-grade filter can theoretically trap particles as small as 0.3 microns (for reference, a human hair can be between 17 and 180 microns wide). A filter with a MERV rating of 13 to 16 is considered a high-range MERV filter and can remove up to 75 percent of all airborne particles 0.3 microns or greater from the air. The airflow restriction imposed by HEPA duct filters in residential air conditioning systems decreases energy efficiency, reduces performance and, in fact, can lower indoor air quality by causing pressure imbalances. In most cases, homes don't have a motor powerful enough to maintain airflow through HEPA filters.
When deciding on a filter, it's important to consider the size of the filter you need and what you want to filter. The main purpose of these air filters is to prevent larger particles from entering and damaging sensitive HVAC components. The real benefit of this filter is that it can be used up to a year before changing it (depending on usage). With a MERV rating of 13, it can filter out microscopic particles of lint, dust mites, spores, pollen, pet dander, fine dust, smoke, viruses and bacteria.
This method continuously filters a percentage of the domestic airflow according to HEPA standards without restricting the volume of air through the duct. If you opt for a HEPA-based air filter, there are few options: HEPA filtration, media air filters, and air filtration systems. It's important to note that UV filters should be used in conjunction with an air filter that deals with the particles themselves. HEPA filters are often used in laboratories, clinics, cleanrooms, and other sensitive locations where air quality must meet high standards. For example, hospitals are likely to be equipped with HEPA filtration to prevent viruses from circulating in the air.
While no HEPA filter will remove all contaminants from indoor air, a high-efficiency filter combined with a well-maintained HVAC system can go a long way.