How To Choose Merv Air Filter

As air moves through a edifice's HVAC system, air filters trap and collect big and small particles such as dust, allergens and microorganisms. According to the American Social club of Heating, Refrigerating and Air conditioning Engineers (ASHRAE), this filtration helps provide healthier indoor air quality. A filter's MERV number indicates how information technology'due south rated to remove these particles. Simply what is MERV rating, exactly?

An air filter's minimum efficiency reporting value (MERV) rating measures how effectively the filter stops dust and other contaminants from passing through the filter and into the air stream. Filters with higher MERV ratings trap minor particles more effectively than filters with lower MERV ratings.

In general, filters with a rating of MERV 16 or below are considered to be HVAC-system-grade filters for residential, commercial and general hospital use. MERV 17 through MERV 20 filters are typically used in surgical operating rooms, clean rooms and other contexts that crave accented cleanliness.

MERV Filter Ratings and Efficiency

When selecting the correct filter for your application, college is not always better. Using an air filter with a MERV rating college than what your furnace or air conditioner manufacturer recommends can actually impair its operation.

The smaller pores in more than highly rated air filters create resistance to air flow, and if the filter is used in an HVAC system that is non designed to handle this resistance, information technology can lower the system's efficiency, decrease indoor air quality, and put strain on the system'southward fan.

MERV Filter Ratings and Air Quality

A position newspaper published past ASHRAE looked at the claim that particle filtration has health benefits. Co-ordinate to this paper, there'south a well established connectedness between higher concentrations of particles in outdoor air and poor health outcomes, so it would make sense that filtering these particles out of indoor air could pb to better health outcomes.

The ASHRAE paper reviewed studies suggesting that:

Particle filtration tin can exist "modestly effective" against allergy and asthma symptoms.
Particle filtration tin can lower the concentration of infectious airborne particles that spread many communicable illnesses, which is why some models suggest that it tin "substantially decrease the portion of affliction manual caused past these small-scale particles."
The health benefits of particle filtration are proportional to "the reduction in total exposure to particles less than 2.5 µm in diameter."

Use the MERV rating chart beneath to understand which filters are all-time for which applications.

MERV Rating Chart

Awarding

CONTROLS THESE CONTAMINANTS

PARTICLE SIZE

MERV 1

MERV 2

MERV iii

MERV 4

· Pre-Filter In Commercial Building

· Residential Furnaces

· Window Air-Conditioning Units

· Pollen

· Dust mites

· Sanding grit

· Fabric/carpet fibers

Filters down to 10.0 micron particle size

MERV 5

MERV 6

MERV 7

MERV eight

· Pre-filters or Terminal Filters

· Commercial Buildings

· Better Residential Buildings

· Industrial Workplaces

· Pigment Booth Inlets

· Pollen

· Dust mites

· Sanding dust

· Textile/carpet fibers

· Mold/spores

· Dust lint

· Cement dust

Filters down to 3.0–10.0 micron particle size

MERV 9

MERV 10

MERV 11

MERV 12

· Pre-Filters or Final Filters

· Hospital Laboratories

· Meliorate Commercial Buildings

· Superior Residential Buildings

· Pollen

· Dust mites

· Sanding dust

· Fabric/rug fibers

· Mold/spores

· Grit lint

· Cement grit

· Legionella

· Pb grit

· Humidifier dust

· Coal grit

· Nebulizer dust

Filters downwardly to 1.0–3.0 micron particle size

MERV 13

MERV xiv

MERV 15

MERV 16

· Terminal Filters

· General Surgery

· Superior Commercial Buildings

· Hospital Inpatient Care

· Smoking Lounges

· Pollen

· Dust mites

· Sanding dust

· Textile/carpet fibers

· Mold/spores

· Dust lint

· Cement grit

· Legionella

· Lead dust

· Humidifier dust

· Coal dust

· Nebulizer dust

· Bacteria

· Tobacco smoke

· Auto fumes

· Sneeze nuclei

· Insecticide dust

· Copier toner

· Pet dander

· Face up pulverization

Filters down to 0.3–one.0 micron particle size

MERV 17

MERV 18

MERV 19

MERV xx

· Last Filter

· Clean Rooms

· Radioactive Materials

· Pharmaceutical Manufacturing Facilities

· Carcinogenic Materials

· Orthopedic Surgery Room

· Pollen

· Dust mites

· Sanding dust

· Textile/carpet fibers

· Mold/spores

· Dust lint

· Cement dust

· Legionella

· Pb grit

· Humidifier dust

· Coal dust

· Nebulizer dust

· Bacteria

· Tobacco smoke

· Motorcar fumes

· Sneeze nuclei

· Insecticide dust

· Copier toner

· Pet dander

· Face powder

· Virus carriers

· Carbon grit

· Sea salt

· Combustion smoke

· Radon progeny

· Smell

· Microscopic allergens

Filters down to less than 0.xxx micron particle size

Pre-Filters vs. Concluding Filters

Air filters can be used every bit final filters or pre-filters. When used as final filters, they are the principal filters for an HVAC organization. Final filters may be used alone in a single-filter organisation, or they may exist used in combination with one or more pre-filters. When used in a multi-filter system, the pre-filters trap the dirt and large particles before the air reaches the final filters downstream, which and so remove the smaller particles. This multi-filter organization extends the life of the more expensive final filters, leading to overall cost savings.

Additional Reading

"Fibrous Filter Media," Philip J. Brown and Christopher L. Cox, eds. Woodhead Publishing, 2017.

The data contained in this commodity is intended for general information purposes merely and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This commodity is not a substitute for review of current applicable authorities regulations, industry standards, or other standards specific to your business concern and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicative standards or consult with an attorney.