How Do HEPA Filters Work?: 2025 Explanation

What Is a HEPA Filter?

HEPA stands for High-Efficiency Particulate Air. These filters are designed to capture 99.97% of particles as small as 0.3 microns in size, which includes dust, pollen, mold spores, bacteria, and even some viruses. This high level of filtration makes HEPA filters a go-to choice for hospitals, clean rooms, and environments requiring stringent air purity standards.

HEPA Filters and Central HVAC Systems

Many homeowners wonder if they can upgrade their HVAC system to use HEPA filters. While this sounds like a straightforward swap, it’s not always feasible. Here’s why:

Size and Compatibility

HEPA filters are typically larger and denser than standard HVAC filters. Most residential HVAC systems are not equipped to handle the increased thickness or pressure drop caused by HEPA filters. Retrofitting your system might require significant modifications that are typically expensive.

Airflow Issues

HVAC systems are designed to work with filters of a specific resistance. The high density of a HEPA filter can reduce airflow, potentially straining your system and leading to inefficiencies or even damage over time.

Maintaining Indoor Air Quality with the Best HVAC Air Filter Available

While true HEPA filters might not be an option, you can opt for high-efficiency pleated filters with a MERV (Minimum Efficiency Reporting Value) rating of 11 to 13. These filters strike a balance between capturing smaller particles and maintaining proper airflow.

Here are some additional tips to achieving the best indoor air quality using high-performance HVAC filters compatible with your system:

• Replace AC Air Filters Regularly: A dirty filter can’t effectively capture pollutants and can strain your HVAC system. Replace your filter every 1-3 months, depending on usage. Follow the guidelines in your HVAC owner’s manual and the instructions on the air filter that you choose when deciding how often to replace your AC air filter.
• Seal Duct Leaks: Ensure that your ductwork is sealed properly to prevent pollutants from bypassing the filter and re-entering your home.
• Schedule Professional HVAC Maintenance: Having a service technician perform HVAC maintenance and cleaning on your system every year ensures that your unit runs efficiently and continues to effectively remove particles and contaminants from indoor air. Scheduling regular professional HVAC maintenance also prolongs the lifespan of your heating and cooling system.
• Clean HVAC Air Ducts: Every few years, schedule professional HVAC air duct cleaning service. While your HVAC filter is designed to trap this particulate matter and prevent it from entering your air ducts, often some particles still get through. These particles can build up inside your HVAC air ducts over time and your HVAC system can become less efficient. Scheduling regular air duct cleaning will ensure that your HVAC system operates efficiently and continues to do its part in protecting indoor air quality.
• Repair HVAC System Problems Promptly: When you encounter problems with your heating and cooling system, schedule HVAC repair service quickly to fix the issue so your system will continue to work properly and help improve indoor air quality.

By following these tips, your HVAC system will be a valuable asset in protecting indoor air quality in your home.

Portable HEPA Filters: A Perfect Complement

If your HVAC system cannot accommodate a HEPA filter, a portable air purifier with a HEPA filter is an excellent alternative. These devices work independently of your HVAC system, cleaning the air in individual rooms or specific areas of your home. Here’s how they can support your HVAC system:

Targeted Filtration

Portable HEPA filters can be placed in high-traffic areas or rooms where allergens and pollutants are most prevalent, like bedrooms or living rooms.

Reduced HVAC Load

By handling some of the air-cleaning burden, portable HEPA filters can help your HVAC system operate more efficiently.

Pollen and Small Particle Removal

Portable units excel at capturing allergens such as pollen, pet dander, and smoke particles, making them ideal for allergy sufferers.

Additional Tips for Cleaner Indoor Air

Here are some bonus tips for maintaining and protecting good indoor air quality in your home:

• Control Basement Humidity: High humidity can promote mold and dust mites. Use a dehumidifier to maintain indoor humidity between 30-50% in your basement.
• Vacuum with a HEPA Filter: Using a HEPA-equipped vacuum cleaner can reduce dust and allergens in your home.
• Ventilation: Proper ventilation helps dilute indoor pollutants. Open windows occasionally or use an energy-recovery ventilator for a controlled exchange of indoor and outdoor air.

By combining these indoor air quality improvement tips with regular HVAC maintenance and proactive air-quality measures, you can breathe easier knowing your home is a haven of clean air. And, understanding how HEPA filters work—and how to use them effectively—puts you one step closer to achieving your indoor air quality goals.