You’ve probably experienced the feeling of confusion when trying to select the correct home air filter for your needs. Which brand is best? Does the price reflect the quality? These are just a few of the questions that make the selection mind-boggling. Let Donelson Air Service Experts try to help you de-mystify the air filter dilemma.
Here’s a tried and true way to tell how efficient your old filter is (NOTE: Do this outdoors or with something below the filter so you don’t end up with a mess): Hold the filter horizontally, then with everyday table salt, start pouring the salt through the filter then see how much comes out the other side. If some or all the salt falls through the filter, then you can imagine that the filter will let dust particles of similar size pass through. You might want to upgrade your filter to higher quality filter that is more efficient.
There are 3 primary considerations when choosing a household air filter; Size, Material and MERV rating.
1) Filter Size
Size is the easiest factor to ascertain. Simply look at the label of your existing filter to see the proper measurements, or just measure it yourself. Typically home air filters are 1” thick, but there are a variety of standard width and height dimensions, and some systems have thicker filters.
2) Material & MERV Rating
Filter efficiencies are given a number from 1-16 called the MERV rating. MERV stands for Minimum Efficiency Reporting Value. This number identifies for the user, under the least efficient conditions, how well the filter is designed to capture contaminants.
To help explain the scale of this system, these are some common MERV ratings and how they connect to efficiencies. This is only a guide, so make sure you read the filter manufacturers’ information when buying specific filters.
Rating Average Filtration Efficiency
MERV 1-4 60-80%
Fiberglass, Disposable Panel, Washable metal/synthetic, self-charging (Passive)
MERV 5-8 80-95%
Pleated, Media panel, Cube
MERV 9-12 >95%
MERV 13-16 >98%
Be Careful About High MERV Ratings
While a higher MERV number may offer better filtration efficiency, it is very important to understand that too high a MERV filter may also take more to operate your heating and air conditioning system. The higher the MERV, the less the air may flow through the system, and the harder the system may need to work. Your goal is to get the right balance between air flow, air filtration level and energy efficiency.
Look at it this way, the most efficient ‘filter’ would probably be a piece of plywood that stops ALL contaminants and all the air from getting into your Nashville home. That's all-out air filtration, but would also be the least comfortable way to go.
Your best bet for most systems would be a MERV 6-8. A higher MERV filter should be used based upon the advice of your Donelson Air Service Experts representative to ensure your system has the capability of moving the proper quantity of air through higher efficiency filters. You normally do not want to lose energy-efficiency for filter efficiency; you want a balance of the two. However, if your family suffers from allergies or respiratory problems and needs a high MERV air filter, consider a whole-home air filtration solution that will satisfy your energy and filter efficiency needs.
Filtration has changed greatly over the past several years. Originally, home air filters were used in the furnace or air handler only to protect the comfort equipment itself. But (in the words of Bob Dylan) the times they are a changing. Nashville area homeowners expect their air filter to save kids from a wide variety of harmful pollutants, dust mites, and even prevent the need for dusting. Dare to dream!