Just go to any home improvement store and the choice of home air filters can be dizzying. What’s the best one? Should you just get the cheapest? These are just two of many of the questions that make the selection mind-boggling. Let Fras-Air/General Service Experts try to help you de-mystify the air filter dilemma.
Here’s an easy way to tell how efficient your current filter is (NOTE: Spare yourself a huge mess by conducting this experiment outside or with something below the filter to help keep things clear): Position the filter horizontally, then with common table salt, pour the salt through the filter then see the quantity that comes out the other side. If some or all the salt falls through the filter, then you know that the filter will let dust that same size flow through. You should probably upgrade your filter to something more efficient.
There are 3 primary considerations when choosing a household air filter; 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 height by width and thickness, or just measure it yourself. Typically home air filters are 1” thick, but there are a number 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 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 common MERV ratings and how they correspond to efficiencies. This is only a guide, so make sure you read the filter manufacturers’ information when shopping for 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%
Extended pleated
MERV 13-16 >98%
Electronic
Be Careful About High MERV Ratings
While a higher MERV number may provide better filtration efficiency, it is critical 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 difficult 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.
Look at it this way, the most efficient ‘filter’ would probably be a piece of plywood that prevents ALL contaminants and all the air from coming inside your Hillsborough home. That's maximum air filtration, but would also be like living in a box.
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 Fras-Air/General Service Experts technician to verify your system has the capability of moving the proper volume of air through higher efficiency filters. You normally do not want to give up energy-efficiency for filter efficiency; you want a balance of the two. However, if your family has 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. In the beginning, home air filters were used in the furnace or air handler only to safeguard the comfort equipment itself. Today it’s a whole new ballgame. Hillsborough area homeowners expect their air filter to save kids from a whole host of harmful pollutants, dust mites, and even prevent the need for dusting. Dare to dream!