Just go to any home improvement store and the choice of home air filters can be dizzying. Which brand is best? Should you just get the cheapest? These are just some of the questions that make the selection mind-boggling. Let Norrell Service Experts attempt to resolve your home air filter questions and allow you to continue enjoying the comfort of your home without concern.
Here’s a tried and true way to determine how efficient your current filter is (NOTE: To avoid a big mess, we highly recommend conducting this test outside or over a protected surface): Hold the filter horizontally, then using common table salt, pour 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 that same size flow through. You should probably upgrade your filter to an air filter that’s more efficient.
Home air filter selection depends primarily on three factors: Size, material and MERV rating.
1) Filter Size
Unless you have the proper size home air filter, you will never enjoy the full effectiveness your system and filter can provide. Simply look at the label of your existing filter to see the dimensions, or just measure it yourself. Most home air filters are 1” thick, but there are a numerous standard width and height dimensions, and some systems have thicker filters.
2) Material & MERV Rating
The efficiencies of filters are rated on a scale of 16, known as MERV ratings. MERV stands for Minimum Efficiency Reporting Value. This number informs the user, under the least efficient conditions, how well the filter is designed to contain contaminants.
To explain MERV ratings more impactfully, these are some typical MERV ratings and how they correspond to efficiencies. This is only a guide, so don’t forget to 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 ensure better filtration efficiency, it is very important to understand that too high a MERV filter may also require more to operate your heating and air conditioning system. The higher the MERV, the more restricted the air may flow through the system, and the harder the system may need to work. Your aim is to get the right balance between air flow, air filtration level and energy efficiency.
Consider it this way, the most efficient ‘filter’ would probably be a piece of plywood that would just trap ALL contaminants and all the air from entering your Birmingham home. That's definitely the “best” air filtration, but would also be a terrible way to live.
A safe bet for most systems would be a MERV 6-8. A higher MERV filter should be used subject to the advice of your Norrell Service Experts technician to verify your system has the capability of moving the proper amount of air through higher efficiency filters. You probably do not want to sacrifice energy-efficiency for filter efficiency; you want a balance of the two. However, if your family suffers from allergies or respiratory problems and the situation necessitates a high MERV rated air filter, consider a whole-home air filtration solution that will meet your energy and filter efficiency needs.
Filtration has changed significantly over the past ten years. In the beginning, home air filters were used in the furnace or air handler only to safeguard the comfort equipment itself. But (in the words of Bob Dylan) the times they are a changing. Birmingham area homeowners expect their air filter to save children from a whole host of harmful pollutants, dust mites, and even prevent the need for dusting. Dare to dream!