AC Filters: What Are MERV Numbers and What do They Mean for Your Mobile AL Home?

Published on: July 20, 2012

AC filters are utilized in some form by every HVAC system and are a critical health component of every household. Effective AC filters not only improve the air quality inside the home, but they also reduce the number of air conditioning service calls that will be required over time.


Air quality inside the home is easily affected and impacts the health of its inhabitants. Poor indoor air quality is not only harmful for those with allergies and asthma, but several studies show that poor indoor air quality contributes to major illnesses such as respiratory problems, pulmonary issues, COPD and even cancer. As the effects of poor indoor air quality become known, homeowners are particularly concerned with the air quality inside their homes. There are two ways to ensure that the air quality inside the home is superior – regular air conditioner maintenance and using a high quality AC filter.


How do AC Filters Contribute to Indoor Air Quality?

AC filters are an important aspect contributing to the overall indoor air quality within the home. AC filters help to maintain healthy indoor air quality by trapping and collecting harmful particles in the air. The better the AC filter, the more effective the filter will be at trapping and collecting particles in the air. Effective AC filters are especially essential for those who suffer from allergies, asthma or respiratory problems.


How Do I Know Which AC Filters Are Most Effective?

A rating system has been developed to assist consumers in evaluating which AC filters are more effective at maintaining the air quality in their homes. The MERV rating is a rating system that assigns a number to each type of AC filter to indicate the filter’s effectiveness in trapping harmful particles in the air. In short, the higher the MERV rating, the more effective the air conditioner filter is at trapping harmful airborne particles. Just as regular air conditioner maintenance is an important aspect of keeping the air quality within the home at acceptable levels, so is utilizing an efficient AC filter.


How to Use MERV Ratings

The acronym “MERV” stands for Minimum Efficiency Reporting Value. The value was developed by the American Society of Heating, Refrigeration and Air Conditioner Engineers (ASHRAE). MERV values range from 1 to 16 and the higher the MERV rating the more effective the filter is at trapping and containing harmful particles in the air. The higher the MERV rating, the smaller the particles may be that are trapped and contained by the filter.

Particles that are harmful to indoor air quality include dust, pollen, tobacco smoke, pet dander, mold spores, and other various allergens. An AC filter with a high MERV rating will trap smaller particles of these harmful substances and eliminate them from the breathable air.

Standard disposable AC filters and permanent metal filters that are often used in residential homes have MERV values between 1 and 4. These AC filters are considered poor in terms of their effectiveness in keeping the indoor air free of pollutants.

Certain agencies recommend different MERV ratings for AC filters. ASHRAE recommends that AC filters in homes have a minimum MERV value of 6. LEED recommends that AC filters have a MERV value of no less than 8. The US Department of Energy recommends a MERV value of no less than 13.

Homeowners in Mobile, AL and in other southern states should spend a little more money and invest in AC filters that have a MERV rating of at least 5. Your air conditioner maintenance technician will be able to provide recommendations for the type of AC filter that is most effective for your HVAC system. HEPA and pleated filters typically have higher MERV ratings than the standard disposable AC filters found in discount stores, which use fiberglass to trap particles.

AC filters with MERV ratings between 1 and 4 will filter dust, dust mites, carpet fibers, and spray paint dust from the air. AC filters with MERV ratings between 5 and 8 will pick up hair spray particles, mold spores, cement dust, and fabric protector spray particles. AC filters with MERV ratings between 8 and 11 will trap lead dust, auto emissions, and humidifier dust. Filters with MERV ratings between 11 and 16 will trap tobacco smoke bacteria and particles released from a human sneeze.

Your air conditioner maintenance technician will advise you with regards to the AC filter that will best meet your needs and budget. Keep in mind, however, that high quality air filters are not an all-inclusive solution. Regular air conditioner maintenance should still be performed to ensure optimal performance from your AC system and the best indoor air quality possible.