The filter in your HVAC system removes impurities from the indoor air. This helps to reduce allergy and asthma symptoms and helps to keep your home cleaner. Air circulating through your home passes through the device and then reenters the rooms in a purified state. You will need to choose the right type based on your needs. Knowing the difference between MERV and HEPA filters will help you to select the option that is appropriate for your home. In this post, we are going to explore everything about MERV and HEPA filters.

MERV Filters: Minimum Efficiency Reporting Value

MERV is an acronym for “Minimum Efficiency Reporting Value”. The MERV rating on an air filter describes its efficiency as a means of reducing the level of 0.3 to 10 micron-sized particles in air which passes through the filter. Higher “MERV” means higher filter efficiency. The purpose of the MERV standard is to permit an “apples to apples” comparison of the filtering efficiency of various air filters.

Air filter efficiency refers to the relative ability of a filter to remove particles of a given size or size range from air passing through the filter. If a filter were 100% efficient, none of the particles in a given size range would escape the filter and air which has passed through such a filter would contain zero particles.

The MERV Efficiency Rating Scale ranges from 1 to 16, with 1 being the lowest efficiency and 16 describing the highest efficiency. The particle size range addressed by the MERV scale is 0.3 to 10 microns. A logical inference is that if an air filter is removing particles down to 0.3-10 microns, it is certainly also at least that efficient at removing larger sized particles.

 

HEPA Filters: High-Efficiency Particulate Air.

Acronym for High-efficiency Particulate Air. A HEPA filter is ranked between 17-20 MERV; the highest group in MERV ratings. All HEPA filters are tested and certified to be at least 99.97% efficiency in removing particles as small as 0.3 microns. HEPA filters are used in all hospitals to stop the spread of infections and keeping them in the bay. This includes bacteria and viruses that are highly contagious in indoor airspace.

Filter media is made up of dense fiberglass threads compressed in unsystematic directions. The purification begins when a force of airflow pulls the particles towards the filter. The filter’s fiberglass would then intercept the particles from proceeding. Most particles will adhere to the fibers when they hit, while some get caught by the curved contours of the fibers. The remaining airborne particles will be trapped when they collide with other molecules in the filter. This leaves only purified air exhausted into the air and the cleaning cycle will repeat itself.

There is a slight drawback to the HEPA filter. While it is supposed to trap impurities for clean air circulation, not all ventilation system is compatible with a HEPA filter. The high fiber density of a HEPA will create a stronger resistance to the airflow thus less air would be able to bypass the filter. Without additional fan power to push air through the filter, the airflow circulation would be inefficient and remain stagnant. In long-run, the wrong filter setup can increase your electricity bills, put extra strain on the system, and eventually damage the HVAC system due to the increased pressure.

 

MERV or HEPA filters: Which Is Better?

 

HEPA filter is the best as it is essentially a top tier MERV 17 to 20 ratings that surpassed even a MERV 16 filter. HEPA filter can capture a minimum of 99.97% impurities in the air as small as 0.3 microns VS MERV 16 filter that captures >95% of particles from 0.3 to 1.0 microns. Given the high particle removal efficiency, HEPA filters are regularly used in nursery homes, educational institutions, and healthcare applications like anterooms, surgery rooms, isolation wards. If you don’t have any allergy or respiratory illnesses, a basic MERV 5 to 8 rating filters will be sufficient in removing dust, dust mites, and pet dander after a few cycles. Suitable for a household that does not have any major air quality concern. For most homes, you should go with filters with MERV 9 rating and above. Even at the lowest tier, it is effective against finer particles like mold, pollen, spore, and VOCs released from cleaning products. Moving on, filter with superior MERV ratings 13 to 16 are commonly used in commercial structures with a superior 75% or greater filtration to capture microscopic particles and prevent the spread of viruses. Ideal for a person that is suffering from asthma, chronic diseases, or a weak immune system.

Breathing to clean air is vital to our health and can prevent diseases from spreading. MERV and HEPA filters are designed to improve ventilation and indoor air quality but not all filters are created equal. To choose the right air filter, understand your needs, and evaluate the air quality in your home. You will also need to find out more information about your furnace system before attempting to install a MERV or HEPA filter. Speak to an HVAC professional to determine what kind of filter is best for your system.

Ultimately, a well-balanced ventilation system is the way to go. As the air in your home will constantly be recirculated, having a MERV-rated filter in your HVAC system will ensure clean air can be achieved. If your HVAC system does not support MERV or HEPA filter upgrade, get a HEPA air purifier for every room and turn it on with at least 2 air changes per hour.

 

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