Air Filtration

First, let’s understand the rating of the air filter before we discuss the types. The rating on filters is based on their ability to capture particles and it is known as MERV (Minimum Efficiency Reporting Value). EPA Article on MERV Rating

The MERV rating ranges from 1 – 16. With 16 being better at capturing particles, the filter is more efficient. However, the more efficient the air filter can restrict airflow. Check with the A/C manufacturer on the recommended MERV rating for filters, as too much airflow restriction can cause the Air Conditioner to work harder to overcome the airflow restriction which in turn, leads to potentially a higher electric bill and more frequent repairs.

Fiberglass Filters

Fiberglass filters are among the most commonly used air filters in HVAC systems. Made of spun glass, they effectively capture large particles of air pollutants from your home. Often referred to as disposable filters, fiberglass filters are designed to last only about 30 days before requiring replacement.

Despite their low cost, fiberglass filters have significant drawbacks. Unlike many other HVAC air filters that can last at least 3 months, these filters must be replaced every 30 days. They also tend to clog quickly, causing your HVAC air handler to work harder and consume more energy. Additionally, fiberglass filters are not designed to remove small particles efficiently, making them a less ideal option for individuals with asthma or allergies.

Pleated Filters

Pleated filters have a MERV rating between 5 and 13 and are made from polyester or cotton folds. These materials effectively filter dust and other airborne pollutants. The pleats in these filters increase the surface area, enhancing their filtering capabilities. Filters with more pleats provide better filtration than those with fewer pleats, capable of trapping allergens such as pet dander and mold spores.

Available in both reusable and disposable options, pleated filters can help suppress HVAC fan noise. However, they require your HVAC system to work harder to pull air through, which can decrease the system’s efficiency. Despite this, pleated filters can slightly improve your home’s air quality, making them a reasonably priced option for those concerned about indoor air quality.

Pleated filters generally need to be replaced every 90 days (or about every three months). However, the replacement frequency can vary depending on several factors, including:

1. Household Size and Occupants: Homes with multiple occupants or pets may require more frequent filter changes, around every 60 days.
2. Allergies or Respiratory Issues: If anyone in the home has allergies or respiratory issues, it’s advisable to replace the filter every 30 to 45 days to ensure better air quality.
3. Filter MERV Rating: Higher MERV-rated filters, which capture more particles, may need to be replaced more often, depending on the level of pollutants in the environment.
4. HVAC System Usage: Homes that frequently use their HVAC system, especially during extreme weather, might need to change filters more often, possibly every 45 to 60 days.

Regularly checking the filter and following the manufacturer’s recommendations can help determine the best replacement schedule for your specific situation.

Washable Filters

Washable air filters are environmentally friendly and cost-effective. While their initial price for HVAC systems is higher, they should be viewed as a long-term investment, lasting for many years. The initial cost is often the only expense since you can wash and reuse these filters repeatedly, eliminating the need to buy new ones every few months.

Proper maintenance is essential to ensure washable air filters work efficiently. They come with specific maintenance instructions that should be followed carefully. It is crucial to ensure the filter is completely dry before reinstalling it, as any remaining moisture can lead to mold and mildew growth, which can then be expelled into the air.

Although washable air filters have a low MERV rating, they are a great long-term investment for those who don’t have specific preferences or requirements for specialty filters.

Media Filters

Media filters offer several advantages for HVAC systems compared to standard high-MERV filters. They provide high levels of filtration without negatively impacting airflow or increasing static pressure. This is due to their larger surface area, which allows for better filtration without causing airflow restrictions.

Easy to maintain, media filters are effective at capturing bacteria and other tiny airborne pollutants. The filtered dirt is sealed within the filter, preventing it from being released back into your home. These filters are durable and cost-effective, requiring replacement only once or twice a year.

Media filters are popular due to their low maintenance requirements and superior filtration capabilities, thanks to their increased surface area. They effectively trap pollutants rather than recirculating them into the air. However, they typically need to be installed by a professional and are not as effective at filtering odors.

HEPA Filters

High-Efficiency Particulate Air (HEPA) filters are highly effective at removing airborne allergens and pollutants, including mold spores and dust. With a MERV rating of around 16, HEPA filters provide the highest level of protection for your home, capable of capturing even the smallest particles, such as tobacco smoke and bacteria.

HEPA filters are particularly beneficial for individuals with allergies or respiratory conditions. However, they require professional installation to ensure they fit your specific HVAC system properly. The design of HEPA filters makes them especially effective at capturing larger pollutants, such as pet dander and pollen. They are also cost-effective, needing replacement only every few years.

The primary advantage of HEPA filters is their exceptional ability to purify the air, making them an ideal choice for those seeking the highest level of air filtration.

UV Filters

UV filters utilize short-wave ultraviolet (UV) light to eliminate bacteria and viruses. The UV lamps in these filters disinfect the air as it passes through the HVAC unit by using germicidal radiation. This makes them highly effective at destroying microorganisms that can harm your health, such as mold spores.

However, UV filters can transform oxygen into ozone, which poses potential health risks. Low levels of ozone exposure can cause coughing and chest pain, while higher levels can exacerbate respiratory conditions like asthma.

While UV filters excel at eliminating bacteria and viruses, they are not as effective at filtering out pollutants like dust. For this reason, they are often integrated into larger filtration systems. The UV light is invisible to the human eye, and the lightbulb typically needs to be replaced every year.

These filters are excellent for killing tough microorganisms, significantly improving indoor air quality. However, they can be costly to install and are ineffective against common pollutants such as gases, fumes, and cigarette smoke.

Electrostatic Filters

Electrostatic filters use small cotton and paper fibers to generate static electricity, which acts as a magnet for dust and other airborne particles. This strong magnetism prevents particles from spreading throughout your home, making electrostatic filters an excellent choice for combating allergens.

These filters come in both disposable and reusable options, providing flexibility. You can choose to wash and reuse them or dispose of them and replace them with new ones when it’s time to change the filter. Electrostatic filters are among the most cost-effective options on the market and are highly effective at improving indoor air quality. While they can handle smaller pollutants efficiently, they struggle with larger particles. Therefore, they might not be the best choice for individuals with respiratory issues.

How to Shop for Replacement Air Filters

1. Determine the Right Size

To choose a replacement air filter, start by identifying the size you need. Locate your existing filter, which is typically in a slot next to your furnace or air handler. Some HVAC systems have filters inside return air ducts in various rooms. These are the grates that draw air in rather than blowing it out.

Measure the filter’s length, width, and depth (or thickness). Ensure it fits properly without gaps around the sides and aligns with any gaskets. If your current filters fit well, note down or photograph the size printed on the filter frame. If unsure, check your equipment’s owner’s manual or contact the manufacturer. Most residential HVAC filters are 1 inch thick, but 4-inch filters are becoming more common.

2. Choose the Right Filtration Level

Pleated HVAC filters can enhance indoor air quality by capturing dust, pollen, and small particles. However, selecting a filter that’s too dense can impede airflow, reducing the efficiency of your HVAC system and potentially causing damage. Conversely, a filter that’s too loose won’t clean the air effectively and might lead to HVAC equipment damage over time.

Finding the right filtration level involves balancing airflow and debris capture. Note your filter’s thickness:

• 1-Inch Thick Filters: These can be challenging to shop for, as high-MERV 1-inch filters can be too restrictive for some systems. Consumer Reports has tested several high-MERV 1-inch filters (MERV 11 and up) that perform well on airflow tests but are often expensive. Lower MERV filters may offer better airflow and cost less but won’t capture as many particles. If in doubt, a MERV 8 pleated filter is a safe choice, providing good airflow and improved debris capture compared to basic fiberglass filters.
• 4-Inch Thick Filters: If your system can accommodate a 4-inch filter, it can capture more debris with relatively porous material due to its larger surface area. A MERV 13 filter is an excellent choice, offering superior air quality at a reasonable price. If you currently use 1-inch filters, consider upgrading your system to fit 4-inch filters by installing a cabinet next to your furnace or air handler, typically costing a few hundred dollars.

3. Install Your New HVAC Filter

Installing a new filter usually requires minimal tools. You might need a screwdriver or pliers to open the filter compartment. Slide out the old filter and insert the new one, ensuring it faces the correct direction as indicated by arrows on the filter frame.

By following these steps, you can select and install the right air filter for your HVAC system, ensuring efficient operation and improved indoor air quality.