Clearing the Air: Understanding Ventilation Filter Classifications


In an era where the majority of our time is spent indoors, the significance of breathing clean, fresh air cannot be overstated. Whether you're nestled at home or busy at work, the air that surrounds you plays a pivotal role in your well-being. Central to maintaining this pristine indoor air quality is the choice of the right filter for your system. Whether you have a PIV, MVHR or any other form of Heating, Ventilation, and Air Conditioning (HVAC), these systems, equipped with the proper filter, are your first line of defence against a variety of airborne pollutants, including dust, mould, pollen, and even microscopic bacteria. This comprehensive guide is designed to explain the world of air filter classifications and assist you in selecting the ideal filter grade to meet your specific environmental and health needs.

Woman holding two different types of filters, looking confused.

Understanding Air Filter Grades

G3/G4 Filters (ISO Coarse)

  • Constructed from basic fiberglass or similar materials.
  • Effective at trapping larger visible particles such as dust, hair, and particles up to around 10 microns in size.
  • An economical choice for maintaining a moderately clean environment in homes or offices.

M5/M6 Filters (ISO ePM10)

  • These filters are made from denser synthetic materials, capable of capturing finer microscopic particles.
  • They excel at filtering out mould spores, pet dander, and pollen as small as 1 micron.
  • Highly recommended for individuals with allergies or pet owners.

F7/F9 Filters (ISO ePM2.5)

  • Utilize highly dense materials to capture extremely small particulate matter.
  • Capable of removing more than 95% of smoke, bacteria, and viruses as small as 0.3 microns.
  • Indispensable in environments requiring stringent air quality control, such as hospitals, laboratories, and food processing areas.

Navigating Filter Ratings

With advancements in our understanding of air quality, filter rating systems have been refined to offer a clearer picture of a filter's performance.

  • EN 779 (Older Standard): Categorized filters into coarse (G), medium (M), and fine (F) classes, based on their efficiency at capturing a specified size of particle.
  • ISO 16890 (Contemporary Standard): The ISO 16890 system is more nuanced and evaluates a filter's efficiency across a spectrum of particle sizes, including PM10, PM2.5, and PM1, providing a more accurate representation of its performance in real-world conditions. Filters are rated from basic “Coarse” up to “ISO ePM1” for superior filtration capability.

The Importance of Regular Maintenance

Choosing the right filter is only part of the solution. To ensure ongoing effectiveness, it is crucial to replace filters regularly. Over time, filters can become clogged with accumulated particles, diminishing their ability to clean the air. Experts typically recommend replacing residential HVAC and MVHR system filters every 6 to 12 months, though it's advisable to consult your system's manufacturer for specific guidance. Regular maintenance not only prolongs the life of your HVAC or MVHR system but also ensures sustained high-quality indoor air.

Having equipped yourself with the knowledge of different filter types, grades, and maintenance requirements, you can now make informed decisions that optimize the performance of your HVAC or MVHR system. This, in turn, guarantees that you and your loved ones can enjoy a healthier, fresher indoor environment.

Filters from Fastlec

At Fastlec, we've got you covered with our extensive range of filters, catering to both basic filtration needs and high-efficiency solutions. While filters are conveniently listed on our unit pages, our dedicated team of experts is also here to assist you in finding and selecting the perfect filter for your home or system. Don't hesitate to reach out via e-mail or phone, for personalized guidance tailored to your specific requirements.

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01903 255424