What Are MERV Number on AC Filters? What Does This Mean for Your Hampton Roads Home?
When you purchase a new air conditioning system, the AC filters come equipped with a Minimum Efficiency Reporting Value (MERV) rating. The MERV rating refers to the ability of the AC filters to trap dust and other airborne debris as it is pulled in from the air and enters into your air conditioning system. People who have respiratory conditions such as asthma or chronic allergies would benefit from having AC filters with the highest possible MERV rating.
How MERV Ratings are Determined
Before AC filters are assigned a MERV rating, scientists working for HVAC manufacturing companies add particles of various sizes to the filter in a laboratory environment. These particles range in size from one micron to 12 microns. Each filter is observed to see how well it trapped each size of micron that passed through it.
After observations have been recorded, each filter is assigned a MERV rating. In most situations, the rating won't be higher than 12. There are some environments that call for AC filters with MERV ratings as high as 16, such as hospitals. Some of the microns that are used to test the efficiency of air conditioning filters are bacteria, pollen, dust, pet dander, wood chips, tobacco smoke and mold spores.
Breakdown of MERV Ratings
Air conditioning filters with MERV ratings of one through four are the most common type found in homes in Hampton Roads, Virginia. These types of filters are disposable and are not as effective as filters with higher MERV ratings. They trap only 60 to 80 percent of all airborne pollutants. Filters with a MERV rating of four or less are unable to trap particles that are smaller than 10 microns.
The next classification of MERV ratings for air conditioning filters is the five to eight range. Filters in this category are most often found in commercial properties in Hampton Roads, although they work well for homeowners as well. AC filters in this category can capture airborne pollutants as small as three microns. You can choose from either disposable or washable filters when selecting a filter with a MERV rating of five to eight.
Filters with MERV ratings between nine and 12 are typically reserved for industrial and commercial use, but they are also available to homeowners. This filter is ideal for people who are specifically allergic to dust. Air conditioning filters in this range must be washed regularly for maximum efficiency. If the filter is allowed to get dirty, it could release particles such as dust and pollen back into the air of your Hampton Roads home. It can also cause your air conditioner to have to work harder at keeping your home cool.
Only hospitals and other very clean environments use filters with a MERV rating that is between 13 and 16. At this level, the filter can trap particles that are as small as .3 microns or more than 99 percent of all airborne pollutants.
Different Types of Air Conditioning and Furnace Filters
When choosing a filter for your air conditioner or furnace, you need to pay attention to more than just the MERV rating. It is also important to determine the type of filter that is most appropriate for your circumstances. The most common type of household filter, with a MERV rating of four or lower, is disposable and inexpensive. However, you exchange efficiency for price and convenience.
Pleated filters are folded on eight sides and have the ability to capture more particles than a typical household filter. For even greater protection from dust and other debris, you may want to consider an electrostatic filter. This type of unit sends out an electrical charge in order to capture airborne pollutants. For the ultimate in protection from airborne elements, consider a HEPA filter.