Generally, the best air filter for your ventilation system depends on your needs. If your home is dirtier or dustier than normal, a higher efficiency filter will be needed. You should therefore know how air filters are rated so allergens, dust, viruses, and other particulates and pathogens are effectively removed before air is recirculated. Here, we’ll explain what you need to know to find an air filter for a ventilation system that satisfies your air quality goals.
Know Your System’s Air Exchange Rate (ACH)
The ACH identifies how many times a building’s entire volume of air is filtered in an hour. If the air circulates every 15 minutes, the ACH will be 4; if air circulates in full every 10 minutes, your system will have an ACH of 6. The higher the ACH, the lower the risk of diseases spreading through the air and the better the ventilation.
To calculate ACH, multiply the volumetric flow rate of air (in cubic feet per minute) by 60. Then divide this value by the total volume of space (length x width x height). The requirements for ACH can vary depending on local regulations and the presence of ozone, volatile organic compounds, or certain chemicals, equipment, and building materials. A 3 to 4 ACH is often recommended (in most areas it’s just 1 to 3 ACH), but high VOC environments may require up to 50 ACH, including those in manufacturing or healthcare.
About MERV Ratings
While it’s important to know how often your HVAC system exchanges air, filter efficiency is another factor worth considering. A filter’s Minimum Efficiency Reporting Value (MERV) defines its ability to capture particles in terms of size. In the HVAC industry, filters with MERV-13 or higher ratings are typically recommended (MERV ratings go up to 20).
Higher-rated filters trap smaller particles. Some are fine enough to capture viruses. Install the highest-rated filter your HVAC unit’s filter slot and fan can handle; the system’s manual or an HVAC contractor can provide the information you need. Also, make sure the filter is installed correctly. Running the fan for longer as well; this is the only time when air will be filtered.
If your indoor air isn’t that dirty, an intermediate MERV rating of 5 to 9 may be enough. If you have a pet, or someone in your household who smokes, a higher-rated filter will be necessary. The goal is to find a filter that effectively removes unwanted particles and doesn’t strain your HVAC system.
Consider a High-Efficiency Particulate Air (HEPA) Filter
A HEPA filter eliminates a minimum of 99.97% of particles as small as 0.3 microns. It exceeds even the highest MERV rating and, if your HVAC and ventilation system can’t accommodate one, a portable HEPA filtration system can be installed. Air purifiers come in various sizes depending on the size of space they’re intended for.
Each system also has a clean air delivery rate (CADR). Knowing the unit’s CADR in cubic feet per minute and the size of the room allows you to identify the right air purifier. The unit should be installed as close to the center of the space as possible.
Even better is a HEPA filter that installs directly in your ductwork. Oftentimes, activated carbon filters and even germicidal UV lights are installed in conjunction with HEPA filtration to maximize its effectiveness.
Types of Air Filters for a Ventilation System
A filter built into the return-air ducts of your central AC system is the most efficient option. There are flat air filters, including matted-fiberglass filters used with furnaces and pleated filters that can last even longer while attracting allergens with an electrostatic charge. Extended media filters are thicker with a stacked design about 8 inches thick; these must be installed professionally.
Also installed in ductwork, electrostatic precipitators apply a high-voltage current to give particles an electric charge. Meanwhile, collector plates on the other end of the unit (with an opposite charge) attract and trap particles. Portable ion units work in a similar way, but send negative ions directly into the air, and use a collection rod to attract charged airborne particles. However, these units may release some ozone, which can irritate the lungs (making them unsuited for individuals with asthma and other respiratory disorders).
Our air filtration experts find the best air filters for ventilation systems in homes throughout Las Vegas. We install air filtration and ventilation systems to improve air quality and make indoor air easier and healthier to breathe. These systems can remove suspended particles, gases, and biological contaminants. Reach out to us via our online contact form or call 702-334-0655 to learn more or request an appointment.