Understanding MERV Filters

What Does MERV Mean?

Minimum Efficiency Reporting Value.

What Is MERV?

A standard rating system from 1 to 20 that measures an air filter’s effectiveness at capturing airborne particles between 0.3 and 10 microns.

MERV filter ratings help determine what filter is best suited for your job.

What do MERV Ratings Mean?

  • MERV 1-4 filters are used for basic filtration of larger particles. Examples of larger particles include lint, dust, and pollen.
  • MERV 5-8 filters are better suited for residential, commercial, and school settings. These filter out particles similar in size to mold spores, hairspray particles, and fine dust.
  • MERV 9-12 filters are known for their high efficiency filtration best suited for homes and businesses with pets or moderate allergies. These filters capture finer dust particles, mold, and pet dander.
  • MERV 13-16 filters are superior filtration best used in Healthcare Facilities, Daycare Centers, Senior Living Centers and other commercial buildings. These filters capture bacteria, tobacco smoke, and some viruses.
  • MERV 17-20 filters are most appropriate for Cleanrooms, Hospitals, and Specialized Filtration Systems. These filters trap 99.97% of particles.

Higher is not always better…

Yes, higher MERV ratings mean better air filtration, but the higher the MERV rating, the higher the airflow resistance. Using a filter with too high MERV ratings can strain the systems fan, increase energy consumption, and potentially cause damage to your equipment. MERV 8-11 filters are most commonly used and provide the best balance of air quality and system performance.

Filter Replacement

Filters should be checked monthly and replaced every 90 days unless you are using them for mold or trying to prevent cross contamination. For mold, filters should be discarded daily or more frequently depending on the severity of the job.

Filter Protection

Not only do filters clean your air but they protect your equipment. It’s not uncommon for us to hear, “Do we really need all these?”

Depending on the job, it can be costly keeping up with filter replacement. Especially with HEPA filters (MERV ratings 17-20). Pre-filters are intended to protect your HEPA filter but what if your job doesn’t require a HEPA filter? Pre-filters are also used to protect your equipment. Fine dust and particles can clog your motor and potentially cause damage.

Carbon Activated Filters

Unlike HEPA filters and pre-filters, Carbon Activated filters specifically target harmful VOCs such as formaldehyde, benzene, paint fumes, smoke, gas/chemical, and mold odors. In addition, the Carbon filter has extremely high surface area with millions of micro-pores where gas molecules and odors stick via absorption.

Carbon filters are generally used as a pre-filter or secondary filter in conjunction with HEPA filters to provide comprehensive air cleaning. They are not effective for particles like dust, pollen, mold spores, pet dander, etc.

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For professionals and homeowners: Barker-Hammer is known for our knowledgeable staff, expertise and extensive supply availability. We rent professional equipment to both professionals an individuals. We provide guidance on equipment use, products and solutions, and testing to ensure your process is complete. If you don’t know where to start, we can help! Contact us for consultations and equipment demonstrations. We will walk you through the process and answer your questions! If you don’t want to DIY this project, we’ll reference our database of professionals in the Midwest and connect you with reliable service providers.

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