If your home's indoor air quality isn't where it should be, then you've probably thought about changing the type of air filter you're currently using. High Efficiency Particulate Air (HEPA) filters are well known for their effectiveness at removing a wide variety of contaminants from indoor air, including viruses, bacteria, and mold spores. If you've thought about installing a HEPA filter in your residential HVAC system, then you may want to check out the following before you take that step.
The Low-Down on HEPA Filters
So what's so great about HEPA filters? For starters, they're commonplace in environments that require the best possible filtration for reducing airborne bacteria, viruses, and other pollutants. These environments often include hospitals, clean rooms, and other areas where airborne particulate removal is paramount.
HEPA filters are made from a pleated mat of fiberglass, activated carbon fibers, and other materials. Under a microscopic view, these fibers form randomly arranged strands that are able to capture particles of varying sizes through the following methods:
- Interception - Airborne particles following the air stream flow come into close contact with a fiber and stick to it.
- Impaction - Larger airborne particles are forced to directly impact a fiber due to air flow velocity and direction.
- Diffusion - Smaller airborne particles take on erratic, random movements similar to Brownian motion and become trapped by either of the above mentioned methods.
As a result, most HEPA filters are capable of trapping up to 99.97 percent of airborne particles as small as 0.3 microns, and there are some filters that can trap particles as small as 0.1 micron.
More Isn't Always Better
Unfortunately, the very properties that make HEPA filters highly effective at removing pollutants and viruses also make them nearly unusable with typical residential HVAC systems. The overly dense makeup of a typical HEPA filter makes it difficult for your HVAC system to push air through it. In other words, it would be like breathing in and out of a small straw when compared to breathing through your nose.
Most residential HVAC systems don't have blower fans that are powerful enough to overcome this resistance and the resulting pressure drops throughout your HVAC system. As a result, you would need to upgrade your HVAC system's blower fan and build a larger custom enclosure for your new HEPA filter. Such modifications could prove expensive depending on the amount of labor needed.
The diminished air flow caused by a HEPA filter can also result in increased energy consumption and a corresponding increase in your utility costs. The unexpected reduction in airflow can also cause various components within your HVAC system to wear out faster, resulting in more frequent and more expensive repairs. HEPA filters can also prove more expensive to purchase than ordinary air filters designed for your residential HVAC system.
Regular Air Filters May Offer Similar Benefits
If you're looking for an effective way of improving your home's indoor air quality, the solution might be right under your nose. Ordinary pleated air filters with a MERV rating of between 7 and 13 are likely to be just as effective as a HEPA filter when it comes to removing airborne particles. Not only do these filters offer an excellent compromise between filtration effectiveness and airflow resistance, but they're also less expensive than actual HEPA filters.
If you're still worried about removing viruses and allergens from your home's indoor air, you may be able to supplement your current air filter with a standalone air purifier. Equipped with their own replaceable HEPA air filters, these devices are designed to capture various airborne particles without adding any strain on your current HVAC system.